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  • 1.
    Al-Husseini, Ali
    et al.
    Department of Clinical Sciences, Neurosurgery, Lund University, Lund, Sweden.
    Fazel Bakhsheshi, Mohammad
    Department of Family Medicine and Community Medicine, Lund University, Lund, Sweden; BrainCool AB, Medicon Village, Lund, Sweden.
    Gard, Anna
    Department of Clinical Sciences Lund, Neurosurgery, Lund University, Lund, Sweden; Skåne University Hospital, Lund, Sweden.
    Tegner, Yelverton
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    Marklund, Niklas
    Department of Clinical Sciences Lund, Neurosurgery, Lund University, Lund, Sweden; Skåne University Hospital, Lund, Sweden.
    Shorter Recovery Time in Concussed Elite Ice Hockey Players by Early Head-and-Neck Cooling: A Clinical Trial2023Ingår i: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 40, nr 11-12, s. 1075-1085Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A sports-related concussion (SRC) is most commonly sustained in contact sports, and is defined as a mild traumatic brain injury. An exercise-induced elevation of core body temperature is associated with increased brain temperature that may accelerate secondary injury processes following SRC, and exacerbate the brain injury. In a recent pilot study, acute head-neck cooling of 29 concussed ice hockey players resulted in shorter time to return-to-play. Here, we extended the clinical trial to include players of 19 male elite Swedish ice hockey teams over five seasons (2016-2021). In the intervention teams, acute head-neck cooling was implemented using a head cap for ≥45 min in addition to the standard SRC management used in controls. The primary endpoint was time from SRC until return-to-play (RTP). Sixty-one SRCs were included in the intervention group and 71 SRCs in the control group. The number of previous SRCs was 2 (median and interquartile range [IQR]: 1.0-2.0) and 1 (IQR 1.0-2.0) in the intervention and control groups, respectively; p = 0.293. Median time to initiate head-neck cooling was 10 min (IQR 7-15; range 5-30 min) and median duration of cooling was 45 min (IQR 45-50; range 45-70 min). The median time to RTP was 9 days in the intervention group (IQR 7.0-13.5 days) and 13 days in the control group (IQR 9-30; p < 0.001). The proportion of players out from play for more than the expected recovery time of 14 days was 24.7% in the intervention group, and 43.7% in controls (p < 0.05). Study limitations include that: 1) allocation to cooling or control management was at the discretion of the medical staff of each team, decided prior to each season, and not by strict randomization; 2) no sham cap was used and evaluations could not be performed by blinded assessors; and 3) it could not be established with certainty that injury severity was similar between groups. While the results should thus be interpreted with caution, early head-neck cooling, with the aim of attenuating cerebral hyperthermia, may reduce post-SRC symptoms and lead to earlier return-to-play in elite ice hockey players.

  • 2.
    Almqvist, Andreas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Pellegrini, Barbara
    Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Verona, Italy.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Emami, Nazanin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Holmberg, H-C
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    A Scientific Perspective on Reducing Ski-Snow Friction to Improve Performance in Olympic Cross-Country Skiing, the Biathlon and Nordic Combined2022Ingår i: Frontiers in Sports and Active Living, E-ISSN 2624-9367, Vol. 4, artikel-id 844883Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Of the medals awarded at the 2022 Winter Olympics in Beijing, 24% were for events involving cross-country skiing, the biathlon and Nordic combined. Although much research has focused on physiological and biomechanical characteristics that determine success in these sports, considerably less is yet known about the resistive forces. Here, we specifically describe what is presently known about ski-snow friction, one of the major resistive forces. Today, elite ski races take place on natural and/or machine-made snow. Prior to each race, several pairs of skis with different grinding and waxing of the base are tested against one another with respect to key parameters, such as how rapidly and for how long the ski glides, which is dependent on ski-snow friction. This friction arises from a combination of factors, including compaction, plowing, adhesion, viscous drag, and water bridging, as well as contaminants and dirt on the surface of and within the snow. In this context the stiffness of the ski, shape of its camber, and material composition and topography of the base exert a major influence. An understanding of the interactions between these factors, in combination with information concerning the temperature and humidity of both the air and snow, as well as the nature of the snow, provides a basis for designing specific strategies to minimize ski-snow friction. In conclusion, although performance on “narrow skis” has improved considerably in recent decades, future insights into how best to reduce ski-snow friction offer great promise for even further advances.

  • 3.
    Andersson, Erik
    et al.
    Department of Health Sciences, Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden.
    Björklund, Glenn
    Department of Health Sciences, Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden.
    Holmberg, Hans-Christer
    Department of Health Sciences, Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden; Swedish Olympic Committee, Stockholm, Sweden.
    Ørtenblad, Niels
    Department of Health Sciences, Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden; Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, Denmark.
    Energy system contributions and determinants of performance in sprint cross-country skiing2017Ingår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 27, nr 4, s. 385-398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To improve current understanding of energy contributions and determinants of sprint-skiing performance, 11 well-trained male cross-country skiers were tested in the laboratory for VO2max , submaximal gross efficiency (GE), maximal roller skiing velocity, and sprint time-trial (STT) performance. The STT was repeated four times on a 1300-m simulated sprint course including three flat (1°) double poling (DP) sections interspersed with two uphill (7°) diagonal stride (DS) sections. Treadmill velocity and VO2 were monitored continuously during the four STTs and data were averaged. Supramaximal GE during the STT was predicted from the submaximal relationships for GE against velocity and incline, allowing computation of metabolic rate and O2 deficit. The skiers completed the STT in 232 ± 10 s (distributed as 55 ± 3% DP and 45 ± 3% DS) with a mean power output of 324 ± 26 W. The anaerobic energy contribution was 18 ± 5%, with an accumulated O2 deficit of 45 ± 13 mL/kg. Block-wise multiple regression revealed that VO2 , O2 deficit, and GE explained 30%, 15%, and 53% of the variance in STT time, respectively (all P < 0.05). This novel GE-based method of estimating the O2 deficit in simulated sprint-skiing has demonstrated an anaerobic energy contribution of 18%, with GE being the strongest predictor of performance.

  • 4.
    Andersson, Erik
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Pellegrini, Barbara
    CeRiSM, Research Center for Sport, Mountain and Health, Rovereto, Italy.
    Sandbakk, Öyvind
    Centre for Elite Sports Research, Norwegian University of Science and Technology, Trondheim, Norway .
    Stöggl, Thomas
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    The effects of skiing velocity on mechanical aspects of diagonal cross-country skiing2014Ingår i: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 13, nr 3, s. 267-284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cycle and force characteristics were examined in 11 elite male cross-country skiers using the diagonal stride technique while skiing uphill (7.5 degrees) on snow at moderate (3.5 +/- 0.3m/s), high (4.5 +/- 0.4m/s), and maximal (5.6 +/- 0.6m/s) velocities. Video analysis (50Hz) was combined with plantar (leg) force (100Hz), pole force (1,500Hz), and photocell measurements. Both cycle rate and cycle length increased from moderate to high velocity, while cycle rate increased and cycle length decreased at maximal compared to high velocity. The kick time decreased 26% from moderate to maximal velocity, reaching 0.14s at maximal. The relative kick and gliding times were only altered at maximal velocity, where these were longer and shorter, respectively. The rate of force development increased with higher velocity. At maximal velocity, sprint-specialists were 14% faster than distance-specialists due to greater cycle rate, peak leg force, and rate of leg force development. In conclusion, large peak leg forces were applied rapidly across all velocities and the shorter relative gliding and longer relative kick phases at maximal velocity allow maintenance of kick duration for force generation. These results emphasise the importance of rapid leg force generation in diagonal skiing.

  • 5.
    Andersson, Erik
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Stöggl, Thomas
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Pellegrini, Barbara
    CeRiSM Research Center for Sport, Mountain and Health University of Verona Rovereto Italy.
    Sandbakk, Øyvind
    Department of Human Movement Science Norwegian University of Science and Technology Trondheim Norway.
    Ettema, Gertjan
    Department of Human Movement Science Norwegian University of Science and Technology Trondheim Norway.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Biomechanical analysis of the herringbone technique as employed by elite cross-country skiers2014Ingår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, nr 3, s. 542-552Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This investigation was designed to analyse the kinematics and kinetics of cross-country skiing at different velocities with the herringbone technique on a steep incline. Eleven elite male cross-country skiers performed this technique at maximal, high, and moderate velocities on a snow-covered 15° incline. They positioned their skis laterally (25 to 30°) with a slight inside tilt and planted their poles laterally (8 to 12°) with most leg thrust force exerted on the inside forefoot. Although 77% of the total propulsive force was generated by the legs, the ratio between propulsive and total force was approximately fourfold higher for the poles. The cycle rate increased with velocity (1.20 to 1.60 Hz), whereas the cycle length increased from moderate up to high velocity, but then remained the same at maximal velocity (2.0 to 2.3 m). In conclusion, with the herringbone technique, the skis were angled laterally without gliding, with the forces distributed mainly on the inside forefoot to enable grip for propulsion. The skiers utilized high cycle rates with major propulsion by the legs, highlighting the importance of high peak and rapid generation of leg forces.

  • 6.
    Andersson, Erik
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Supej, Matej
    Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.
    Sandbakk, Øyvind
    Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Sperlich, Billy
    Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany .
    Stöggl, Thomas
    Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Analysis of sprint cross-country skiing using a differential global navigation satellite system2010Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 110, nr 3, s. 585-595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose was to examine skiing velocities, gear choice (G2-7) and cycle rates during a skating sprint time trial (STT) and their relationships to performance, as well as to examine relationships between aerobic power, body composition and maximal skiing velocity versus STT performance. Nine male elite cross-country skiers performed three tests on snow: (1) Maximum velocity test (Vmax) performed using G3 skating, (2) Vmax test performed using double poling (DP) technique and (3) a STT over 1,425 m. Additional measurements of VO2max during roller skiing and body composition using iDXA were made. Differential global navigation satellite system data were used for position and velocity and synchronized with video during STT. The STT encompassed a large velocity range (2.9-12.9 m s-1) and multiple transitions (21-34) between skiing gears. Skiing velocity in the uphill sections was related to gear selection between G2 and G3. STT performance was most strongly correlated to uphill time (r = 0.92, P < 0.05), the percentage use of G2 (r = -0.72, P < 0.05), and DP Vmax (r = -0.71, P < 0.05). The velocity decrease in the uphills from lap 1 to lap 2 was correlated with VO2max (r = -0.78, P < 0.05). Vmax in DP and G3 were related to percent of racing time using G3. In conclusion, the sprint skiing performance was mainly related to uphill performance, greater use of the G3 technique, and higher DP and G3 maximum velocities. Additionally, VO2max was related to the ability to maintain racing velocity in the uphills and lean body mass was related to starting velocity and DP maximal speed.

  • 7.
    Apro, William
    et al.
    Swedish Sch Sport & Hlth Sci, Astrand Lab, SE-11486 Stockholm, Sweden.
    Moberg, Marcus
    Swedish Sch Sport & Hlth Sci, Astrand Lab, SE-11486 Stockholm, Sweden.
    Hamilton, D. Lee
    Univ Stirling, Hlth & Exercise Sci Res Grp, Stirling FK9 4LA, Scotland.
    Ekblom, Björn
    Swedish Sch Sport & Hlth Sci, Astrand Lab, SE-11486 Stockholm, Sweden.
    van Hall, Gerrit
    Univ Copenhagen, Rigshosp, Dept Biomed Sci, DK-1168 Copenhagen, Denmark.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Blomstrand, Eva
    Swedish Sch Sport & Hlth Sci, Astrand Lab, SE-11486 Stockholm, Sweden.
    Resistance exercise-induced S6K1 kinase activity is not inhibited in human skeletal muscle despite prior activation of AMPK by high-intensity interval cycling2015Ingår i: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 308, nr 6, s. E470-E481Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Combining endurance and strength training in the same session has been reported to reduce the anabolic response to the latter form of exercise. The underlying mechanism, based primarily on results from rodent muscle, is proposed to involve AMPK-dependent inhibition of mTORC1 signaling. This hypothesis was tested in eight trained male subjects who in randomized order performed either resistance exercise only (R) or interval cycling followed by resistance exercise (ER). Biopsies taken from the vastus lateralis before and after endurance exercise and repeatedly after resistance exercise were assessed for glycogen content, kinase activity, protein phosphorylation, and gene expression. Mixed muscle fractional synthetic rate was measured at rest and during 3 h of recovery using the stable isotope technique. In ER, AMPK activity was elevated immediately after both endurance and resistance exercise (similar to 90%, P < 0.05) but was unchanged in R. Thr(389) phosphorylation of S6K1 was increased severalfold immediately after exercise (P < 0.05) in both trials and increased further throughout recovery. After 90 and 180 min recovery, S6K1 activity was elevated (similar to 55 and similar to 110%, respectively, P < 0.05) and eukaryotic elongation factor 2 phosphorylation was reduced (similar to 55%, P < 0.05) with no difference between trials. In contrast, markers for protein catabolism were differently influenced by the two modes of exercise; ER induced a significant increase in gene and protein expression of MuRF1 (P < 0.05), which was not observed following R exercise only. In conclusion, cycling-induced elevation in AMPK activity does not inhibit mTOR complex 1 signaling after subsequent resistance exercise but may instead interfere with the hypertrophic response by influencing key components in protein breakdown.

  • 8.
    Apró, William
    et al.
    Swedish Sch Sport & Hlth Sci, Stockholm, Sweden.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Rooyackers, Olav
    Karolinska Univ Hosp, Huddinge, Sweden.
    Blomstrand, Eva
    Swedish Sch Sport & Hlth Sci, Stockholm, Sweden.
    Is leucine induced p70S6 kinase phosphorylation following resistance exercise dependent on elevated phenylalanine levels in human skeletal muscle?2010Ingår i: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 24, s. lb273-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this study was to investigate the specific role of

    leucine in the stimulation of the mammalian target of rapamycin

    signalling pathway. Six male subjects performed four heavy

    resistance exercise sessions, each separated by approximately one

    week. Subjects were randomly supplemented with one of four

    drinks: placebo (flavored water), leucine or essential amino acids

    (EAA) with and without leucine. Immediately following each

    exercise session, four subjects were infused with a flooding dose of

    L-[2H5] phenylalanine (Inf) while two subjects served as controls

    (Ctrl). Muscle biopsies were taken before and one hour after

    exercise. In the Ctrl group, resistance exercise resulted in a

    substantial increase (45-fold) in p70 kinase phosphorylation

    when all EAA were ingested, whereas ingestion of leucine alone

    had no greater effect than that of placebo. In the Inf group,

    however, ingestion of leucine alone and EAA increased p70

    phosphorylation to a similar extent (35-fold). The divergent

    signalling response in the two groups suggests that leucine alone is

    insufficient to increase p70

    phosphorylation. Indeed, in the Inf

    group, there was a strong correlation (r=0.91) between

    p70 phosphorylation and the product of muscle leucine and

    phenylalanine levels. These results suggest that the stimulatory

    effect of leucine on p70 phosphorylation is dependent on

    elevated muscle phenylalanine levels. Supported by the Swedish

    National Centre for Research in Sports

     

  • 9.
    Apró, William
    et al.
    Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Amino Acid-induced S6K1 Activity in Human Skeletal Muscle is Mediated By Increased mTor/Rheb Interaction: 128 June 1, 11: 15 AM - 11: 30 AM2016Ingår i: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, nr 5 Suppl 1, s. 17-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cell culture studies have shown that amino acids activate mTORC1 signaling by increasing the interaction between mTOR and its essential activator Rheb. However, the existence of this mechanism in human skeletal muscle remains to be determined.

    PURPOSE: To determine if increased mTORC1 signaling in response to amino acids in human skeletal muscle is due to an increased interaction between mTOR and Rheb.

    METHODS: Eight well trained men performed resistance exercise on two separate occasions. In connection with the exercise, subjects were supplemented with flavored water (Pla) and essential amino acids (EAA) in a double-blind, randomized cross-over design. Muscle biopsies were taken in the vastus lateralis muscle before, immediately after and 90 and 180 min post exercise. Activity of the mTORC1 pathway was assessed by a radiolabeled in-vitro kinase assay for its immediate downstream target S6K1. Protein-protein interactions were determined by western blot following co-immunoprecipitation of mTOR with Rheb. Co-immunoprecipitation was performed on pooled muscle samples from three of the eight subjects.

    RESULTS: Activity of S6K1 remained unchanged immediately after exercise in both trials. However, at 90 min post exercise, S6K1 activity increased by approximately 2- and 8-fold (p<0.05) from baseline the Pla and EAA trials, respectively. At the 180 min time point, S6K1 activity remained elevated in both trials being approx. 3-fold higher in the Pla trial and 5-fold higher (p<0.05) in the EAA trial. The fold-change in mTOR and Rheb interaction largely resembled the activity pattern of S6K1 in both trials; in the Pla trial the fold-change was 0.9, 1.3 and 1.4 while in the EAA trial the fold-change was 1.6, 2.9 and 1.9 immediately after, 90 min after and 180 min after exercise, respectively.

    CONCLUSIONS: The large increase in S6K1 activity following EAA intake appears to be mediated by an increased interaction between mTOR and its proximal activator Rheb. This is the first time this mechanism has been demonstrated in human skeletal muscle.

    Ladda ner (pdf)
    SUMMARY01
  • 10.
    Bakkman, Linda
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Sahlin, K
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Quantitative and qualitative adaptation of human skeletal muscle mitochondria to hypoxic compared to2007Ingår i: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 190, nr 3, s. 243-251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    AIM: To investigate if training during hypoxia (H) improves the adaptation of muscle oxidative function compared with normoxic (N) training performed at the same relative intensity. METHOD: Eight untrained volunteers performed one-legged cycle training during 4 weeks in a low-pressure chamber. One leg was trained under N conditions and the other leg under hypobaric hypoxia (526 mmHg) at the same relative intensity as during N (65% of maximal power output, W(max)). Muscle biopsies were taken from vastus lateralis before and after the training period. Muscle samples were analysed for the activities of oxidative enzymes [citrate synthase (CS) and cytochrome c oxidase (COX)] and mitochondrial respiratory function. RESULTS: W(max) increased with more than 30% over the training period during both N and H. CS activity increased significantly after training during N conditions (+20.8%, P < 0.05) but remained unchanged after H training (+4.5%, ns) with a significant difference between conditions (P < 0.05 H vs. N). COX activity was not significantly changed by training and was not different between exercise conditions [+14.6 (N) vs. -2.3% (H), ns]. Maximal ADP stimulated respiration (state 3) expressed per weight of muscle tended to increase after N (+31.2%, P < 0.08) but not after H training (+3.2%, ns). No changes were found in state four respiration, respiratory control index, P/O ratio, mitochondrial Ca(2+) resistance and apparent Km for oxygen. CONCLUSION: The training-induced increase in muscle oxidative function observed during N was abolished during H. Altitude training may thus be disadvantageous for adaptation of muscle oxidative function.

  • 11.
    Bauer, Nikolai
    et al.
    Institute of Sport and Sport Science, Heidelberg University, Heidelberg, Germany; Working Group Exercise Oncology, Department of Medical Oncology, National Center for Tumor Diseases (NCT), Heidelberg University Hospital, Heidelberg, Germany.
    Sperlich, Billy
    Chair of Integrative and Experimental Exercise Science and Training, Institute of Sport Science, Julius-Maximilians-Universität of Würzburg, Judenbühlweg 11, 97082, Würzburg, Germany.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, Stockholm, Sweden.
    Engel, Florian A.
    Chair of Integrative and Experimental Exercise Science and Training, Institute of Sport Science, Julius-Maximilians-Universität of Würzburg, Judenbühlweg 11, 97082, Würzburg, Germany.
    Effects of High-Intensity Interval Training in School on the Physical Performance and Health of Children and Adolescents: A Systematic Review with Meta-Analysis2022Ingår i: Sports Medicine - Open, E-ISSN 2198-9761, Vol. 8, nr 1, artikel-id 50Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Background Performance of high-intensity interval training (HIIT) by children and adolescents improves physical and health-related fitness, as well as cardiometabolic risk factors.

    Objectives To assess the impact of HIIT performed at school, i.e. both in connection with physical education (intra-PE) and extracurricular sports activities (extra-PE), on the physical fitness and health of children and adolescents.

    Methods PubMed and SPORTDiscus were searched systematically utilizing the following criteria for inclusion: (1) healthy children and adolescents (5–18 years old) of normal weight; (2) HIIT performed intra- and/or extra-PE for at least 5 days at an intensity ≥ 80% of maximal heart rate (HRmax) or peak oxygen uptake (VO2peak) or as Functional HIIT; (3) comparison with a control (HIIT versus alternative interventions); and (4) pre- and post-analysis of parameters related to physical fitness and health. The outcomes with HIIT and the control interventions were compared utilizing Hedges’ g effect size (ES) and associated 95% confidence intervals.

    Results Eleven studies involving 707 participants who performed intra-PE and 388 participants extra-PE HIIT were included. In comparison with the control interventions, intra-PE HIIT improved mean ES for neuromuscular and anaerobic performance (ES jump performance: 5.89 ± 5.67 (range 1.88–9.90); ES number of push-ups: 6.22 (range n.a.); ES number of sit-ups: 2.66 ± 2.02 (range 1.24–4.09)), as well as ES fasting glucose levels (− 2.68 (range n.a.)) more effectively, with large effect sizes. Extra-PE HIIT improved mean ES for neuromuscular and anaerobic performance (ES jump performance: 1.81 (range n.a.); ES number of sit-ups: 2.60 (range n.a.)) to an even greater extent, again with large effect sizes. Neither form of HIIT was more beneficial for parameters related to cardiorespiratory fitness than the control interventions.

    Conclusion Compared to other forms of exercise (e.g. low-to-moderate-intensity running or walking), both intra- and extra-PE HIIT result in greater improvements in neuromuscular and anaerobic performance, as well as in fasting levels of glucose in school children.

  • 12.
    Beaven, Martyn
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Willis, Sarah
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Cook, Christian
    School of Sport, Health and Exercise Sciences, Bangor University, Bangor, United Kingdom.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Physiological comparison of concentric and eccentric arm cycling in males and females2014Ingår i: PLOS ONE, E-ISSN 1932-6203, Vol. 5, nr 9, artikel-id e112079Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lower body eccentric exercise is well known to elicit high levels of muscular force with relatively low cardiovascular and metabolic strain. As a result, eccentric exercise has been successfully utilised as an adaptive stressor to improve lower body muscle function in populations ranging from the frail and debilitated, to highly-trained individuals. Here we investigate the metabolic, cardiorespiratory, and energy costs of upper body eccentric exercise in a healthy population. Seven men and seven women performed 4-min efforts of eccentric (ECC) or concentric (CON) arm cycling on a novel arm ergometer at workloads corresponding to 40, 60, and 80% of their peak workload as assessed in an incremental concentric trial. The heart rate, ventilation, cardiac output, respiratory exchange ratio, and blood lactate concentrations were all clearly greater in CON condition at all of the relative workloads (all p<0.003). Effect size calculations demonstrated that the magnitude of the differences in VO2 and work economy between the ECC and CON exercise ranged from very large to extremely large; however, in no case did mechanical efficiency (ηMECH) differ between the conditions (all p>0.05). In contrast, delta efficiency (ηΔ), as previously defined by Coyle and colleagues in 1992, demonstrated a sex difference (men>women; p<0.05). Sex differences were also apparent in arteriovenous oxygen difference and heart rate during CON. Here, we reinforce the high-force, low cost attributes of eccentric exercise which can be generalised to the muscles of the upper body. Upper body eccentric exercise is likely to form a useful adjunct in debilitative, rehabilitative, and adaptive clinical exercise programs; however, reports of a shift towards an oxidative phenotype should be taken into consideration by power athletes. We suggest delta efficiency as a sensitive measure of efficiency that allowed the identification of sex differences.

  • 13.
    Björklund, Glenn
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Stöggl, Thomas
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    The effects of prior high intensity double poling on subsequent diagonal stride skiing characteristics2015Ingår i: SpringerPlus, E-ISSN 2193-1801, Vol. 4, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To investigate the influence of prior high intensity double poling (DP) on physiological and biomechanical responses during subsequent diagonal stride (DIA). Methods: Eight well-trained male cross-country skiers (age 22 ± 3 yr; VO2max 69 ± 3 ml · kg−1 · min−1) roller-skied on a treadmill sequentially for 3 min at 90% DIA VO2max (DIA1), 3 min at 90% DP VO2peak and 3 min at 90% DIA VO2max (DIA2). Cardio-respiratory responses were monitored continuously and gases and metabolites in blood from the a. femoralis, v. femoralis and v. subclavia determined. Pole and plantar forces and EMG from 6 lower- and upper-body muscles were measured. Results: VO2 decreased from DIA1 to DP and increased again to DIA2 (both P &lt; 0.05), with no difference between the DIA sessions. Blood lactate rose from DIA1 to DP to DIA2. O2 extraction was attenuated during DP (P &lt; 0.05), but was the same during DIA1 and DIA2. EMGRMS for arm muscles during poling phase, as well as peak pole force and cycle rate were higher, while leg muscle activity was lower during DP than both sessions of DIA (all P &lt; 0.05). The ratio of upper-/whole-body EMGRMS correlated negatively with O2 extraction in the arms during both sessions of DIA (P &lt; 0.05). Conclusions: In well-trained skiers skiing at high-intensity DP prior to DIA did not influence VO2, muscle activation or forces in the latter. At race intensity DP does not influence the distribution of work between upper- and lower-body during a subsequent bout of DIA. O2 extraction is coupled to technical skills during skiing.

  • 14.
    Björklund, Glenn
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Laaksonen, Marko
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Holmberg, H. -C
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Blood lactate recovery and respiratory responses during diagonal skiing of variable intensity2011Ingår i: European Journal of Sport Science, ISSN 1746-1391, E-ISSN 1536-7290, Vol. 11, nr 5, s. 317-326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aims of the study were to investigate blood lactate recovery and respiratory variables during diagonal skiing of variable intensity in skiers at different performance levels. Twelve male cross-country skiers classified as elite (n=6; VO2max=73±3 ml. kg-1. min-1) or moderately trained (n=6; VO2max=61±5 ml. kg-1. min-1) performed a 48-min variable intensity protocol on a treadmill using the diagonal stride technique on roller skis, alternating between 3 min at 90% and 6 min at 70% of VO2max. None of the moderately trained skiers were able to complete the variable intensity protocol and there was a difference in time to exhaustion between the two groups (elite: 45.0±7.3 min; moderately trained: 31.4±10.4 min) (P&lt;0.05). The elite skiers had lower blood lactate concentrations and higher blood base excess concentrations at all 70% workloads than the moderately trained skiers (all P&lt;0.05). In contrast, VE/VO2 and VE/VCO2 at the 70% VO2max workloads decreased independently of group (P&lt;0.05). Partial correlations showed that VO2max was related to blood lactate at the first and second intervals at 70% of VO2max (r=-0.81 and r=-0.82; both P&lt;0.01) but not to VE/VO2, VE/VCO2 or the respiratory exchange ratio. Our results demonstrate that during diagonal skiing of variable intensity, (1) elite skiers have superior blood lactate recovery compared with moderately trained skiers, who did not show any lactate recovery at 70% of VO2max, suggesting it is an important characteristic for performance; and (2) the decreases in respiratory exchange ratio, VE/VO2, and VE/VCO2 do not differ between elite and moderately trained skiers.

  • 15.
    Björklund, Glenn
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Stöggl, Thomas
    Department of Sport Science and Kinesiology, University of Salzburg, Austria.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Biomechanical influenced differences in O2 extraction in diagonal skiing: arm versus leg2010Ingår i: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 42, nr 10, s. 1899-1908Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biomechanically Influenced Differences in O-2 Extraction in Diagonal Skiing: Arm versus Leg. Med. Sci. Sports Exerc., Vol. 42, No. 10, pp. 1899-1908, 2010. Purpose: This study aimed to determine whether the differences in oxygen extraction and lactate concentration in arms and legs during cross-country skiing are related to muscle activation or force production and how these differences are influenced by a reduction in exercise intensity. Methods: Nine well-trained male cross-country skiers (age = 22 +/- 3 yr, (V) over dotO(2max) = 5.3 +/- 0.3 L.min(-1) and 69 +/- 3 mL.kg(-1).min(-1)) performed diagonal skiing on a treadmill for 3 min at 90% followed by 6 min at 70% of (V) over dotO(2max). During the final minute of each workload, arterial, femoral, and subclavian venous blood was collected for determination of blood gases, pH, and lactate. EMG was recorded from six upper-and lower-body muscles, and leg and pole forces were measured. Cardiorespiratory variables were monitored continuously. Results: Oxygen extraction in the legs was higher than that in the arms at both 90% and 70% of (V) over dotO(2max) (92% +/- 3% vs 85% +/- 6%, P < 0.05 and 90% +/- 3% vs 78% +/- 8%, P < 0.001). This reduction with decreased workload was more pronounced in the arms (-9.8% +/- 7.7% vs -3.2% +/- 3.2%, P < 0.01). EMGRMS for the arms was higher, and pole ground contact time was greater than the corresponding values for the legs (both P < 0.01). At both intensities, the blood lactate concentration was higher in the subclavian than that in the femoral vein but was lowered more in the subclavian vein when intensity was reduced (all P < 0.001). Conclusions: The higher muscle activation (percentage of maximal voluntary isometric contraction) in the arms and the longer ground contact time of the poles than the legs contribute to the lower oxygen extraction and elevated blood lactate concentration in the arms in diagonal skiing. The better lactate recovery in the arms than that in the legs is aided by greater reductions in muscle activation and pole force when exercise intensity is reduced.

  • 16.
    Born, D. -P
    et al.
    Integrative and Experimental Exercise Science, Institute for Sport Sciences, University of Wuerzburg, Wuerzburg, Germany .
    Faiss, R.
    Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland .
    Willis, Sara J.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Strahler, J.
    Clinical Biopsychology, University of Marburg, Marburg, Germany.
    Millet, G. P.
    ISSUL Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sperlich, B.
    Integrative and Experimental Exercise Science, Institute for Sport Sciences, University of Wuerzburg, Wuerzburg, Germany .
    Circadian variation of salivary immunoglobin A, alpha-amylase activity and mood in response to repeated double-poling sprints in hypoxia2016Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, nr 1, s. 1-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To assess the circadian variations in salivary immunoglobin A (sIgA) and alpha-amylase activity (sAA), biomarkers of mucosal immune function, together with mood during 2 weeks of repeated sprint training in hypoxia (RSH) and normoxia (RSN). Methods: Over a 2-week period, 17 competitive cross-country skiers performed six training sessions, each consisting of four sets of five 10-s bouts of all-out double-poling under either normobaric hypoxia (FiO2: 13.8 %, 3000 m) or normoxia. The levels of sIgA and sAA activity and mood were determined five times during each of the first (T1) and sixth (T6) days of training, as well as during days preceding (baseline) and after the training intervention (follow-up). Results: With RSH, sIgA was higher on T6 than T1 (P = 0.049), and sAA was increased on days T1, T6, and during the follow-up (P &lt; 0.01). With RSN, sIgA remained unchanged and sAA was elevated on day T1 only (P = 0.04). Similarly, the RSH group demonstrated reduced mood on days T1, T6, and during the follow-up, while mood was lowered only on T1 with RSN (P &lt; 0.01). Conclusions: The circadian variation of sIgA and sAA activity, biomarkers of mucosal immune function, as well as mood were similar on the first day of training when repeated double-poling sprints were performed with or without hypoxia. Only with RSH did the levels of sIgA and sAA activity rise with time, becoming maximal after six training sessions, when mood was still lowered. Therefore, six sessions of RSH reduced mood, but did not impair mucosal immune function. © 2015, Springer-Verlag Berlin Heidelberg.

  • 17.
    Born, D. -P
    et al.
    Julius-Maximilians-Universität Würzburg, Institut für Sportwissenschaft, Integrative und Experimentelle Trainingswissenschaft, Judenbühlweg 11, 97082 Würzburg, Germany .
    Hoppe, M. W.
    Arbeitsbereich Bewegungswissenschaft, Sportwissenschaft, Bergische Universität Wuppertal, Germany .
    Lindner, N.
    Julius-Maximilians-Universität Würzburg, Institut für Sportwissenschaft, Integrative und Experimentelle Trainingswissenschaft, Judenbühlweg 11, 97082 Würzburg, Germany .
    Freiwald, J.
    Arbeitsbereich Bewegungswissenschaft, Sportwissenschaft, Bergische Universität Wuppertal, Germany .
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sperlich, B.
    Julius-Maximilians-Universität Würzburg, Institut für Sportwissenschaft, Integrative und Experimentelle Trainingswissenschaft, Judenbühlweg 11, 97082 Würzburg, Germany .
    Hitze, Kälte und Höhenexposition im Fuβball: Adaptive Mechanismen und Verhaltensstrategien in variierenden Umweltbedingungen2014Ingår i: Sportverletzung, Sportschaden, ISSN 0932-0555, E-ISSN 1439-1236, Vol. 28, nr 1, s. 17-23Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Football is played worldwide and players often have to cope with hot and cold temperatures as well as high altitude conditions. The upcoming and past world championships in Brazil, Qatar and South Africa illustrate the necessity for behavioural strategies and adaptation to extreme environmental conditions. When playing football in the heat or cold, special clothing, hydration and nutritional and acclimatisation strategies are vital for high-level performance. When playing at high altitude, the reduced oxygen partial pressure impairs endurance performance and alters the technical and tactical requirements. Special high-altitude adaptation and preparation strategies are essential for football teams based at sea-level in order to perform well and compete successfully. Therefore, the aim of the underlying review is: 1) to highlight the difficulties and needs of football teams competing in extreme environmental conditions, 2) to summarise the thermoregulatory, physiological, neuronal and psychological mechanism, and 3) to provide recommendations for coping with extreme environmental conditions in order to perform at a high level when playing football in the heat, cold and at high altitude.

  • 18.
    Born, Dennis
    et al.
    Dept of Sport Science, University of Wuppertal, Wuppertal, Germany.
    Sperlich, Billy
    Dept of Sport Science, University of Wuppertal, Wuppertal, Germany.
    Holmberg, Hans-Christer
    Avdelningen för hälsovetenskap, Mittuniversitetet, Sweden.
    Bringing light into the dark: effects of compression clothing on performance and recovery2013Ingår i: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 8, nr 1, s. 4-18Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    To assess original research addressing the effect of the application of compression clothing on sport performance and recovery after exercise, a computer-based literature research was performed in July 2011 using the electronic databases PubMed, MEDLINE, SPORTDiscus, and Web of Science. Studies examining the effect of compression clothing on endurance, strength and power, motor control, and physiological, psychological, and biomechanical parameters during or after exercise were included, and means and measures of variability of the outcome measures were recorded to estimate the effect size (Hedges g) and associated 95% confidence intervals for comparisons of experimental (compression) and control trials (noncompression). The characteristics of the compression clothing, participants, and study design were also extracted. The original research from peer-reviewed journals was examined using the Physiotherapy Evidence Database (PEDro) Scale. Results indicated small effect sizes for the application of compression clothing during exercise for shortduration sprints (10-60 m), vertical-jump height, extending time to exhaustion (such as running at VO2maxor during incremental tests), and time-trial performance (3-60 min). When compression clothing was applied for recovery purposes after exercise, small to moderate effect sizes were observed in recovery of maximal strength and power, especially vertical-jump exercise; reductions in muscle swelling and perceived muscle pain; blood lactate removal; and increases in body temperature. These results suggest that the application of compression clothing may assist athletic performance and recovery in given situations with consideration of the effects magnitude and practical relevance.

  • 19.
    Born, Dennis
    et al.
    Dept. of Sport Science, University of Wuppertal, Wuppertal, Germany .
    Zinner, Christoph
    Inst. of Training Science and Sport Informatics, German Sport University Cologne, Cologne, Germany .
    Herlitz, B
    Dept. of Sport Science, University of Wuppertal, Wuppertal, Germany .
    Richter, K
    Dept. of Sport Science, University of Wuppertal, Wuppertal, Germany .
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sperlich, Billy
    Dept. of Sport Science, University of Wuppertal, Wuppertal, Germany .
    Muscle oxygenation asymmetry in ice speed skaters is not compensated by compression2014Ingår i: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 9, nr 1, s. 58-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE:

    The present investigation assessed tissue oxygenation and local blood volume in both vastus lateralis muscles during 3000 m race simulations in elite speed skaters on ice and the effects of leg compression on physiological, perceptual and performance measures.

    METHODS:

    Ten (6 female) elite ice speed skaters completed two on-ice trials with and without leg compression. Tissue oxygenation and local blood volume in both vastus lateralis muscles was assessed by applying near-infrared spectroscopy (NIRS). Continuous measures of oxygen uptake, ventilation, heart rate and velocity were conducted throughout the race simulations as well as blood lactate concentration and ratings of perceived exertion before and after the trials. In addition, lap times were assessed.

    RESULTS:

    The investigation of tissue oxygenation in both vastus lateralis muscles revealed an asymmetry (P<0.00; effect size=1.81) throughout the 3000 m race simulation. The application of leg compression did not affect oxygenation asymmetry (smallest P=0.99; largest effect size=0.31) or local blood volume (P=0.33; 0.95). Lap times (P=0.88; 0.43), velocity (P=0.24; 0.84), oxygen uptake (P=0.79; 0.10), ventilation (P=0.11; 0.59), heart rate (P=0.21; 0.89), blood lactate concentration (P=0.82; 0.59) and ratings of perceived exertion (P=0.19; 1.01) were also unaffected by the different types of clothing.

    CONCLUSION:

    Elite ice speed skaters show an asymmetry in tissue oxygenation of both vastus lateralis muscles during 3000 m events remaining during the long gliding phases along the straight sections of the track. Based on our data, we conclude no performance enhancing benefits from wearing leg compression under a normal racing suit.

  • 20.
    Born, Dennis-Peter
    et al.
    Department of Sport Science, University of Wuppertal, Fuhlrottstraße 10, 42119, Wuppertal, Germany; Department of Sport Sciences, Integrative and Experimental Exercise Science, University of Würzburg, 97082, Würzburg, Germany.
    Holmberg, Hans-Christer
    Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, 83125, Östersund, Sweden.
    Goernert, Florian
    Department of Sport Science, University of Wuppertal, Fuhlrottstraße 10, 42119, Wuppertal, Germany.
    Sperlich, Billy
    Department of Sport Science, University of Wuppertal, Fuhlrottstraße 10, 42119, Wuppertal, Germany; Department of Sport Sciences, Integrative and Experimental Exercise Science, University of Würzburg, 97082, Würzburg, Germany.
    A novel compression garment with adhesive silicone stripes improves repeated sprint performance – a multi-experimental approach on the underlying mechanisms2014Ingår i: BMC Sports Science, Medicine and Rehabilitation, E-ISSN 2052-1847, Vol. 6, nr 21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND:

    Repeated sprint performance is determined by explosive production of power, as well as rapid recovery between successive sprints, and there is evidence that compression garments and sports taping can improve both of these factors.

    METHODS:

    In each of two sub-studies, female athletes performed two sets of 30 30-m sprints (one sprint per minute), one set wearing compression garment with adhesive silicone stripes (CGSS) intended to mimic taping and the other with normal clothing, in randomized order. Sub-study 1 (n = 12) focused on cardio-respiratory, metabolic, hemodynamic and perceptual responses, while neuronal and biomechanical parameters were examined in sub-study 2 (n = 12).

    RESULTS:

    In both sub-studies the CGSS improved repeated sprint performance during the final 10 sprints (best P < 0.01, d = 0.61). None of the cardio-respiratory or metabolic variables monitored were altered by wearing this garment (best P = 0.06, d = 0.71). Also during the final 10 sprints, rating of perceived exertion by the upper leg muscles was reduced (P = 0.01, d = 1.1), step length increased (P = 0.01, d = 0.91) and activation of the m. rectus femoris elevated (P = 0.01, d = 1.24), while the hip flexion angle was lowered throughout the protocol (best P < 0.01, d = 2.28) and step frequency (best P = 0.34, d = 0.2) remained unaltered.

    CONCLUSION:

    Although the physiological parameters monitored were unchanged, the CGSS appears to improve performance during 30 30-m repeated sprints by reducing perceived exertion and altering running technique.

  • 21.
    Bortolan, Lorenzo
    et al.
    Department of Engineering for Innovation Medicine, University of Verona, 37129 Verona, Italy; CeRiSM, Sport Mountain and Health Research Centre, University of Verona and Trento, 38068 Rovereto, Italy.
    Pellegrini, Barbara
    Department of Engineering for Innovation Medicine, University of Verona, 37129 Verona, Italy; CeRiSM, Sport Mountain and Health Research Centre, University of Verona and Trento, 38068 Rovereto, Italy.
    Verdel, Nina
    Faculty of Sport, University of Ljubljana, Gortanova 22, 1000 Ljubljana, Slovenia.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. School of Kinesiology, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.
    Supej, Matej
    Faculty of Sport, University of Ljubljana, Gortanova 22, 1000 Ljubljana, Slovenia.
    Development of Equipment for Ski Mountaineering, a New Olympic Event2023Ingår i: Applied Sciences, ISSN 2076-3417, Vol. 13, nr 9, artikel-id 5339Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ski mountaineering, a new Olympic winter sport involving both climbing and descending snowy slopes, requires considerable physical and technical abilities, as well as highly specialized equipment. Herein, we briefly describe this equipment and its influence on performance and consider potential future advances. Skis, boots, and bindings must be light enough to facilitate climbing uphill (in which as much as 85% of the total racing time is spent) and, at the same time, provide stability and safety in often-challenging descents. A skier must be able to easily and rapidly attach and remove the adhesive skins under the skis that provide grip while skiing uphill. Poles and their baskets must be designed optimally to transfer propulsive force and help maintain balance. Despite the popularity of ski mountaineering, research on this sport is scarce, and we indicate a number of areas wherein improvements in equipment could potentially advance both performance and safety. Such advances must be based on a better understanding of the biomechanics of ski mountaineering, which could be obtained with novel sensor technology and can be best achieved via more extensive collaboration between researchers, skiers and their coaches, and manufacturers of ski mountaineering equipment.

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  • 22.
    Bortolan, Lorenzo
    et al.
    Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.
    Savoldelli, Aldo
    Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.
    Pellegrini, Barbara
    Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.
    Modena, Roberto
    Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.
    Sacchi, Massimiliano
    Oberalp S.p.A., Bolzano, Italy.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    Supej, Matej
    Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.
    Ski Mountaineering: Perspectives on a Novel Sport to Be Introduced at the 2026 Winter Olympic Games2021Ingår i: Frontiers in Physiology, E-ISSN 1664-042X, Vol. 12, artikel-id 737249Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ski mountaineering is a rapidly growing winter sport that involves alternately climbing and descending slopes and various racing formats that differ in length and total vertical gain, as well as their distribution of downhill and uphill sections. In recent years, both participation in and media coverage of this sport have increased dramatically, contributing, at least in part, to its inclusion in the 2026 Winter Olympics in Milano-Cortina. Here, our aim has been to briefly describe the major characteristics of ski mountaineering, its physiological and biomechanical demands, equipment, and training/testing, as well as to provide some future perspectives. Despite its popularity, research on this discipline is scarce, but some general characteristics are already emerging. Pronounced aerobic capacity is an important requirement for success, as demonstrated by positive correlations between racing time and maximal oxygen uptake and oxygen uptake at the second ventilatory threshold. Moreover, due to the considerable mechanical work against gravity on demanding uphill terrain, the combined weight of the athlete and equipment is inversely correlated with performance, prompting the development of both lighter and better equipment in recent decades. In ski mountaineering, velocity uphill is achieved primarily by more frequent (rather than longer) strides due primarily to high resistive forces. The use of wearable technologies, designed specifically for analysis in the field (including at elevated altitudes and cold temperatures) and more extensive collaboration between researchers, industrial actors, and coaches/athletes, could further improve the development of this sport.

     

  • 23. Brink-Elfegoun, T.
    et al.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Nordlund Ekblom, M.
    Ekblom, B.
    Neuromuscular and circulatory adaptation during combined arm and leg exercise with different maximal work loads2007Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 101, nr 5, s. 603-611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cardiopulmonary kinetics and electromyographic activity (EMG) during exhausting exercise were measured in 8 males performing three maximal combined arm + leg exercises (cA+L). These exercises were performed at different rates of work (mean ± SD; 373 ± 48, 429 ± 55 and 521 ± 102 W) leading to different average exercise work times in all tests and subjects. reached a plateau versus work rate in every maximal cA+L exercise (range 6 min 33 s to 3 min 13 s). The three different exercise protocols gave a maximal oxygen consumption of 4.67 ± 0.57, 4.58 ± 0.52 and 4.66 ± 0.53 l min−1 (P = 0.081), and a maximal heart rate (HRmax) of 190 ± 6, 189 ± 4 and 189 ± 6 beats min−1 (P = 0.673), respectively. Root mean square EMG (EMGRMS) of the vastus lateralis and the triceps brachii muscles increased with increasing rate of work and time in all three cA+L protocols. The study demonstrates that despite different maximal rates of work, leading to different times to exhaustion, the circulatory adaptation to maximal exercise was almost identical in all three protocols that led to a plateau. The EMGRMS data showed increased muscle recruitment with increasing work rate, even though the HRmax and was the same in all three cA+L protocols. In conclusion, these findings do not support the theory of the existence of a central governor (CG) that regulates circulation and neuronal output of skeletal muscles during maximal exercise. Thibault Brink-Elfegoun and Hans-Christer Holmberg contributed equally to this article.

  • 24.
    Bucher Sandbakk, Silvana
    et al.
    Swedish Winter Sports Research Centre.
    Supej, Matej
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sandbakk, Øyvind
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Downhill turn techniques and associated physical characteristics in cross-country skiers2014Ingår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, nr 4, s. 708-716Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three dominant techniques are used for downhill turning in cross-country skiing. In this study, kinematic, kinetic, and temporal characteristics of these techniques are described and related to skier strength and power. Twelve elite female cross-country skiers performed six consecutive turns of standardized geometry while being monitored by a Global Navigation Satellite System. Overall time was used as an indicator of performance. Skiing and turning parameters were determined from skier trajectories; the proportional use of each technique was determined from video analysis. Leg strength and power were determined by isometric squats and countermovement jumps on a force plate. Snow plowing, parallel skidding, and step turning were utilized for all turns. Faster skiers employed less snow plowing and more step turning, more rapid deceleration and earlier initiation of step turning at higher speed (r = 0.80–0.93; all P < 0.01). Better performance was significantly correlated to higher mean speed and shorter trajectory (r

    = 0.99/0.65; both P < 0.05) and to countermovement jump characteristics of peak force, time to peak force, and rate of force development (r  = -0.71/0.78/-0.83; all P < 0.05). In conclusion, faster skiers used step turning to a greater extent and exhibited higher maximal leg power, which enabled them to combine high speeds with shorter trajectories during turns.

  • 25.
    Burgueño, Rafael
    et al.
    Department of Education, University of Almeria, Almeria, Spain.
    Lindqvist, Anna-Karin
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    Nyberg, Lars
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    Chillon, Palma
    PROFITH "PROmoting FITness and Health Through Physical Activity" Research Group, Sport and Health University Research Institute (iMUDS), Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain.
    Rutberg, Stina
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    Basic psychological need satisfaction in active commuting to and from school BPNS-ACS(SWE)2023Ingår i: Journal of Transport & Health, ISSN 2214-1405, E-ISSN 2214-1413, Vol. 30, artikel-id 101618Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    The absence of appropriate Swedish-language instrumentation to assess active commuting to school has largely hampered the study of the individual factors of the children, such as autonomy, competence, and relatedness to active commuting to school.

    Purpose

    Building upon self-determination theory, the objective of this research was to gather evidence of the validity and reliability of the Swedish version of the Basic Psychological Need Satisfaction in Active Commuting to and from School (BPNS-ACS) tool.

    Methods

    The cross-sectional and purposive sample included 273 children (51.28% girls) from urban areas.

    Results

    Confirmatory factor analysis underpinned the three-factor correlated model, which was invariant across gender. Evidence in support of discriminant and convergent validity and reliability was gathered. Criterion validity evidence was met by positive and significant predictions of autonomy, competence, and relatedness satisfaction on active commuting to and from school.

    Conclusions

    The Swedish version of the BPNS-ACS is a psychometrically robust measure of children’s perceptions of autonomy, competence, and relatedness satisfaction in active commuting to school and could be used to assess the effects of school-based interventions on need satisfaction for active commuting to school.

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  • 26.
    Calbet, J. A. L.
    et al.
    Univ Las Palmas Gran Canaria, Dept Phys Educ, Las Palmas Gran Canaria 35017, Canary Islands, Spain.
    Ponce-Gonzalez, J. G.
    Univ Las Palmas Gran Canaria, Dept Phys Educ, Las Palmas Gran Canaria 35017, Canary Islands, Spain.
    Perez-Suarez, I.
    Univ Las Palmas Gran Canaria, Dept Phys Educ, Las Palmas Gran Canaria 35017, Canary Islands, Spain.
    de la Calle Herrero, J.
    Univ Las Palmas Gran Canaria, Dept Phys Educ, Las Palmas Gran Canaria 35017, Canary Islands, Spain.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    A time-efficient reduction of fat mass in 4 days with exercise and caloric restriction2015Ingår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 25, nr 2, s. 223-233Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To determine whether a fast reduction in fat mass can be achieved in 4 days by combining caloric restriction (CR: 3.2kcal/kg body weight per day) with exercise (8-h walking+45-min arm cranking per day) to induce an energy deficit of approximate to 5000kcal/day, 15 overweight men underwent five experimental phases: pretest, exercise+CR for 4 days (WCR), control diet+reduced exercise for 3 days (DIET), and follow-up 4 weeks (POST1) and 1 year later (POST2). During WCR, the diet consisted solely of whey protein (n=8) or sucrose (n=7) (0.8g/kg body weight per day). After WCR, DIET, POST1, and POST2, fat mass was reduced by a mean of 2.1, 2.8, 3.8, and 1.9kg (P<0.05), with two thirds of this loss from the trunk; and lean mass by 2.8, 1.0, 0.5, and 0.4kg, respectively. After WCR, serum glucose, insulin, homeostatic model assessment, total and low-density lipoprotein cholesterol and triglycerides were reduced, and free fatty acid and cortisol increased. Serum leptin was reduced by 64%, 50%, and 33% following WCR, DIET, and POST1, respectively (P<0.05). The effects were similar in both groups. In conclusion, a clinically relevant reduction in fat mass can be achieved in overweight men in just 4 days by combining prolonged exercise with CR.

  • 27. Calbet, J
    et al.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap (-2013).
    Rosdahl, H
    van Hall, G
    Jensen-Urstad, M
    Saltin, Bengt
    Why do the arms extract less oxygen than the legs during exercise?2005Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 289, s. 1448-1458Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To determine whether conditions for O2 utilization and O2 off-loading from the hemoglobin are different in exercising arms and legs, six cross-country skiers participated in this study. Femoral and subclavian vein blood flow and gases were determined during skiing on a treadmill at 76% maximal O2 uptake (O2 max) and at O2 max with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise), and leg skiing (predominantly leg exercise). The percentage of O2 extraction was always higher for the legs than for the arms. At maximal exercise (diagonal stride), the corresponding mean values were 93 and 85% (n = 3; P < 0.05). During exercise, mean arm O2 extraction correlated with the PO2 value that causes hemoglobin to be 50% saturated (P50: r = 0.93, P < 0.05), but for a given value of P50, O2 extraction was always higher in the legs than in the arms. Mean capillary muscle O2 conductance of the arm during double poling was 14.5 (SD 2.6) ml·min–1·mmHg–1, and mean capillary PO2 was 47.7 (SD 2.6) mmHg. Corresponding values for the legs during maximal exercise were 48.3 (SD 13.0) ml·min–1·mmHg–1 and 33.8 (SD 2.6) mmHg, respectively. Because conditions for O2 off-loading from the hemoglobin are similar in leg and arm muscles, the observed differences in maximal arm and leg O2 extraction should be attributed to other factors, such as a higher heterogeneity in blood flow distribution, shorter mean transit time, smaller diffusing area, and larger diffusing distance, in arms than in legs. diffusing capacity; fatigue; oxygen extraction; performance; training

  • 28.
    Calbet, J.
    et al.
    Department of Physical Education. University of Las Palmas de Gran Canaria, Spain.
    Jensen-Urstad, M.
    Department of Cardiology, Karolinska Institute, 171 77 Stockholm, Sweden.
    van Hall, G.
    The Copenhagen Muscle Research Centre, Rigshospitalet, 2200 Copenhagen N, Denmark.
    Holmberg, Hans-Christer
    Department Physiology-Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden.
    Rosdahl, H.
    Department of Sport and Health Sciences, University College of Physical Education and Sports, SEM -114 86 Stockholm, Sweden.
    Saltin, Bengt
    The Copenhagen Muscle Research Centre, Rigshospitalet, 2200 Copenhagen N, Denmark.
    Maximal vascular conductances during whole body upright exercise in humans2004Ingår i: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 558, nr 1, s. 319-331Artikel i tidskrift (Refereegranskat)
  • 29.
    Carlsson, Katarina
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap.
    Önsten, Malin
    Luleå tekniska universitet, Institutionen för hälsovetenskap.
    Knäfunktion efter ACL-rekonstruktion: En litteraturöversikt2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Introduktion: Det finns en outtalad självklarhet att operation skulle vara en överlägsenbehandlingsmetod jämfört med enbart rehabilitering vid korsbandsskador. Det senaste årethar dock en långtidsuppföljning av Frobell et al(2015) visat att operation vid främrekorsbandsskada inte gav ett överlägset rehabiliteringsresultat jämfört med konservativbehandling. Operation medför en ökad risk för artros och dessutom en ökad vårdkostnad. Syfte: Med denna litteraturöversikt undersöka hur patientens knäfunktion förändras efterrekonstruktion av ACL för att se om detta går i linje med Frobell et al (2015) resultat. Metod: Sökning gjordes i PubMed, AMED, SveMed+, SportDiscus, Scopus och Web ofScience. Mesh-termer som användes var ”anterior cruciate ligament reconstruction” AND”rehabilitation”, avgränsat till RCT-studier. Resultat: 20 studier inkluderades. Det sammanlagda resultatet visade att patientens subjektivt upplevda funktion samt objektivtuppmätta funktion förbättrades av operationen. Konklusion: Resultatet i denna översiktvisar på att operation förbättrar knäfunktionen vid ACL-skada, fler studier krävs för attundersöka verkningsmekanismer bakom förbättringen och optimering avbehandlingsmetod.

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  • 30.
    Carlsson, Lars
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Lind, Britta
    Royal Inst Technol KTH, Sch Technol & Hlth, Stockholm, Sweden .
    Laaksonen, Marko
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Berglund, Bo
    Karolinska Inst, Dept Internal Med, S-10401 Stockholm, Sweden.
    Brodin, Lars-Åke
    Royal Inst Technol KTH, Sch Technol & Hlth, Stockholm, Sweden .
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Enhanced systolic myocardial function in elite endurance athletes during combined arm-and-leg exercise2011Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, nr 6, s. 905-913Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim here was to employ color tissue velocity imaging (TVI), to test the hypothesis that highly trained endurance athletes exhibit enhanced systolic function of the left ventricular (LV) myocardium both at rest and during combined arm-and-leg exercise in comparison with untrained subjects. For each of the ten elite male (EG) and ten matched control participants (CG), LV dimensions and systolic function were assessed at rest using echocardiography. Subsequently, these subjects exercised continuously on a combined arm-and-leg cycle ergometer for 3 min each at 50, 60, 70, 80, 90 and 100% of VO2max. Oxygen uptake, heart rate, systolic blood pressure (SBP) and peak contraction systolic velocities of the LV myocardium (PSV) were recorded in the end of each level. At rest, the trained and untrained groups differed with respect to LV dimensions, but not systolic function. At 60–100% VO2max, the EG group demonstrated both higher PSV and SBP. The observation that the EG athletes had higher PSV than CG during exercise at 60–100% VO2max, but not at rest or at 50% of VO2max, suggested an enhanced systolic capacity. This improvement is likely to be due to an enhanced inotropic contractility, which only becomes apparent during exercise.

  • 31.
    Cheng, Arthur J.
    et al.
    Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden .
    Place, Nicolas
    Institute of Movement Sciences and Sports Medicine, Medicine Faculty, Geneva University, Geneva, Switzerland .
    Bruton, Joseph D.
    Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden .
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Westerblad, Håkan
    Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden .
    Doublet discharge stimulation increases sarcoplasmic reticulum Ca2+ release and improves performance during fatiguing contractions in mouse muscle fibres2013Ingår i: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 591, nr 15, s. 3739-3748Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Double discharges (doublets) of motor neurones at the onset of contractions increase both force and rate of force development during voluntary submaximal contractions. The purpose of this study was to examine the role of doublet discharges on force and myoplasmic free [Ca2+] ([Ca2+](i)) during repeated fatiguing contractions, using a stimulation protocol mimicking the in vivo activation pattern during running. Individual intact fibres from the flexor digitorum brevis muscle of mice were stimulated at 33 degrees C to undergo 150 constant-frequency (five pulses at 70 Hz) or doublet (an initial, extra pulse at 200 Hz) contractions at 300 ms intervals. In the unfatigued state, doublet stimulation resulted in a transient (approximate to 10 ms) approximate doubling of [Ca2+](i), which was accompanied by a greater force-time integral (approximate to 70%) and peak force (approximate to 40%) compared to constant frequency contractions. Moreover, doublets markedly increased force-time integral and peak force during the first 25 contractions of the fatiguing stimulation. In later stages of fatigue, addition of doublets increased force production but the increase in force production corresponded to only a minor portion of the fatigue-induced reduction in force. In conclusion, double discharges at the onset of contractions effectively increase force production, especially in early stages of fatigue. This beneficial effect occurs without additional force loss in later stages of fatigue, indicating that the additional energy cost induced by doublet discharges to skeletal muscle is limited.

  • 32.
    Cheng, Arthur J.
    et al.
    Karolinska Institutet.
    Willis, Sarah J.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Zinner, Christoph
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Chaillou, Thomas
    Karolinska Institutet; Örebro universitet.
    Ivarsson, Niklas
    Karolinska Institutet.
    Ørtenblad, Niels
    University of Southern Denmark, Odense, Denmark.
    Lanner, Johanna T.
    Karolinska Institutet.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Westerblad, Håkan
    Karolinska Institutet.
    Post-exercise recovery of contractile function and endurance in humans and mice is accelerated by heating and slowed by cooling skeletal muscle2017Ingår i: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 595, nr 24, s. 7413-7426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Key points: We investigated whether intramuscular temperature affects the acute recovery of exercise performance following fatigue-induced by endurance exercise. Mean power output was better preserved during an all-out arm-cycling exercise following a 2 h recovery period in which the upper arms were warmed to an intramuscular temperature of ˜ 38°C than when they were cooled to as low as 15°C, which suggested that recovery of exercise performance in humans is dependent on muscle temperature. Mechanisms underlying the temperature-dependent effect on recovery were studied in intact single mouse muscle fibres where we found that recovery of submaximal force and restoration of fatigue resistance was worsened by cooling (16-26°C) and improved by heating (36°C). Isolated whole mouse muscle experiments confirmed that cooling impaired muscle glycogen resynthesis. We conclude that skeletal muscle recovery from fatigue-induced by endurance exercise is impaired by cooling and improved by heating, due to changes in glycogen resynthesis rate.

    Manipulation of muscle temperature is believed to improve post-exercise recovery, with cooling being especially popular among athletes. However, it is unclear whether such temperature manipulations actually have positive effects. Accordingly, we studied the effect of muscle temperature on the acute recovery of force and fatigue resistance after endurance exercise. One hour of moderate-intensity arm cycling exercise in humans was followed by 2 h recovery in which the upper arms were either heated to 38°C, not treated (33°C), or cooled to ∼15°C. Fatigue resistance after the recovery period was assessed by performing 3 × 5 min sessions of all-out arm cycling at physiological temperature for all conditions (i.e. not heated or cooled). Power output during the all-out exercise was better maintained when muscles were heated during recovery, whereas cooling had the opposite effect. Mechanisms underlying the temperature-dependent effect on recovery were tested in mouse intact single muscle fibres, which were exposed to ∼12 min of glycogen-depleting fatiguing stimulation (350 ms tetani given at 10 s interval until force decreased to 30% of the starting force). Fibres were subsequently exposed to the same fatiguing stimulation protocol after 1-2 h of recovery at 16-36°C. Recovery of submaximal force (30 Hz), the tetanic myoplasmic free [Ca2+] (measured with the fluorescent indicator indo-1), and fatigue resistance were all impaired by cooling (16-26°C) and improved by heating (36°C). In addition, glycogen resynthesis was faster at 36°C than 26°C in whole flexor digitorum brevis muscles. We conclude that recovery from exhaustive endurance exercise is accelerated by raising and slowed by lowering muscle temperature.

  • 33.
    Danielsen, Jorgen
    et al.
    Norwegian Univ Sci & Technol, Dept Neurosci, Ctr Elite Sports Res, Trondheim, Norway.
    Sandbakk, Oyvind
    Norwegian Univ Sci & Technol, Dept Neurosci, Ctr Elite Sports Res, N-7489 Trondheim, Norway.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Ettema, Gertjan
    Norwegian Univ Sci & Technol, Dept Neurosci, Ctr Elite Sports Res, Trondheim, Norway.
    Mechanical Energy and Propulsion in Ergometer Double Poling by Cross-country Skiers2015Ingår i: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, nr 12, s. 2586-2594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose This study aims to investigate fluctuations in total mechanical energy of the body (E-body) in relation to external ergometer work (W-erg) during the poling and recovery phases of simulated double-poling cross-country skiing. Methods Nine male cross-country skiers (mean SD age, 24 5 yr; mean +/- SD body mass, 81.7 +/- 6.5 kg) performed 4-min submaximal tests at low-intensity, moderate-intensity, and high-intensity levels and a 3-min all-out test on a ski ergometer. Motion capture analysis and load cell recordings were used to measure body kinematics and dynamics. From these, W-erg, E-body (sum of the translational, rotational, and gravitational potential energies of all segments), and their time differentials (power P) were calculated. P(tot)the rate of energy absorption or generation by muscles-tendonswas defined as the sum of P-body and P-erg. ResultsE(body) showed large fluctuations over the movement cycle, decreasing during poling and increasing during the recovery phase. The fluctuation in P-body was almost perfectly out of phase with P-erg. Some muscle-tendon energy absorption was observed at the onset of poling. For the rest of poling and throughout the recovery phase, muscles-tendons generated energy to do W-erg and to increase E-body. Approximately 50% of cycle P-tot occurred during recovery for all intensity levels. Conclusions In double poling, the extensive contribution of the lower extremities and trunk to whole-body muscle-tendon work during recovery facilitates a direct transfer of E-body to W-erg during the poling phase. This observation reveals that double poling involves a unique movement pattern different from most other forms of legged terrestrial locomotion, which are characterized primarily by inverted pendulum or spring-mass types of movement.

  • 34.
    Davis, Louise
    et al.
    Department of Psychology, Umeå University, Sweden; Umeå School of Sports Science, Umeå University, Umeå, Sweden.
    Jowett, Sophia
    School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom.
    Sörman, Daniel
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    The Importance of Positive Relationships for Coaches’ Effectiveness and Well-Being2023Ingår i: International Sport Coaching Journal, ISSN 2328-918X, E-ISSN 2328-9198, Vol. 10, nr 2, s. 254-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study investigated the role of quality coach–athlete relationships and coaching efficacy on coaches’ well-being and performance. We examined whether coaches’ direct and meta-perspectives of the coach–athlete relationship quality predicted dimensions of coaches’ efficacy, hedemonic and eudaimonic well-being, and coach-related performance. A total of 233 male and female Swedish coaches from various team and individual sports completed the Coach–Athlete Relationship Questionnaire, the Coaching Efficacy Scale, Positive and Negative Affect Scale, Subjective Vitality Scale, and a one-single item developed to measure perceived coach performance. Structural equation modelling analyses revealed that quality coach–athlete relationships as defined by closeness, commitment, and complementarity associated with all four dimensions of coach efficacy. While coach–athlete relationship quality was linked with coaches’ positive affect, vitality, and satisfaction with coaching performance, only the motivational dimension of coach efficacy was associated with indicators of coach well-being and coach-related performance. Further analyses showed that the motivational dimension of coach efficacy explained the link between coach–athlete relationship quality, well-being, and coach-related performance. Overall, the findings extended the coach efficacy model by investigating the coach–athlete relationship as a predictor and coach well-being as an outcome. Our findings emphasize the importance of relationships for coaches’ efficacy and well-being.

  • 35.
    Davis, Louise
    et al.
    Department of Psychology, Umeå University, Umeå, Sweden; School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
    Jowett, Sophia
    School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
    Sörman, Daniel
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    Ekelund, Rebecka
    Department of Psychology, Umeå University, Umeå, Sweden; School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
    The role of quality relationships and communication strategies for the fulfilment of secure and insecure athletes' basic psychological needs2023Ingår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 40, nr 21, s. 2424-2436Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The correlates of coach-athlete relationship quality have been the focus of research for over a decade; however, little is known about the mediating and moderating mechanisms underlying these associations. The present study conducted a moderated mediation analysis to examine (a) the mediating role of communication strategies (via COMPASS) on the association between the quality of the coach-athlete relationship and athlete psychological needs satisfaction and (b) whether individual differences in athletes&apos; attachment style (secure, anxious, avoidant) moderates the mediational relationship. 350 Swedish athletes representing a range of sports and competition levels completed a multi-section questionnaire. Mediation and moderation analysis partially found that coach-athlete relationship quality and athletes basic psychological needs were associated via the COMPASS strategies of support, motivation, assurance and openness. It was also found that athletes secure attachment with their coach significantly moderated the mediated effects of motivation and support. These findings highlight the practical utility of motivation, support, openness and assurance strategies in enhancing the quality of the coach-athlete relationship. Moreover, these findings demonstrate that the attachment orientation of athletes towards their coaches play a significant role in determining what communication strategies to use to enhance both the relationship quality and an athlete&apos;s competence, autonomy and relatedness.

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  • 36. Drobnič, Miha
    et al.
    Verdel, Nina
    Holmberg, Hans-Christer
    Supej, Matej
    Garmin Running Dynamics Pod ni veljaven za določanje kontaktnih časov pri teku na mestu: [Garmin Running Dynamics Pod is not valid for determining contact times while running in place]2023Ingår i: Revija Šport, ISSN 0353-7455, Vol. 71, nr 3/4, s. 183-187Artikel i tidskrift (Övrigt vetenskapligt)
  • 37.
    Dueking, Peter
    et al.
    Univ Wurzburg, Inst Sport Sci, Dept Sports Sci, Integrat & Expt Training Sci, D-97070 Wurzburg, Germany.
    Hotho, Andreas
    Univ Wurzburg, Data Min & Informat Retrieval Grp, Comp Sci Artificial Intelligence & Appl Comp Sci, D-97070 Wurzburg, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Fuss, Franz Konstantin
    RMIT Univ, Sch Engn, Dept Mech & Automot Engn, Melbourne, Vic, Australia.
    Sperlich, Billy
    Univ Wurzburg, Inst Sport Sci, Dept Sports Sci, Integrat & Expt Training Sci, D-97070 Wurzburg, Germany.
    Comparison of Non-Invasive Individual Monitoring of the Training and Health of Athletes with Commercially Available Wearable Technologies2016Ingår i: Frontiers in Physiology, E-ISSN 1664-042X, Vol. 7, artikel-id 71Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Athletes adapt their training daily to optimize performance, as well as avoid fatigue, overtraining and other undesirable effects on their health. To optimize training load, each athlete must take his/her own personal objective and subjective characteristics into consideration and an increasing number of wearable technologies (wearables) provide convenient monitoring of various parameters. Accordingly, it is important to help athletes decide which parameters are of primary interest and which wearables can monitor these parameters most effectively. Here, we discuss the wearable technologies available for non-invasive monitoring of various parameters concerning an athlete's training and health. On the basis of these considerations, we suggest directions for future development. Furthermore, we propose that a combination of several wearables is most effective for accessing all relevant parameters, disturbing the athlete as little as possible, and optimizing performance and promoting health.

  • 38.
    Dunst, Anna Katharina
    et al.
    Fachbereich Ausdauer, Institut für Angewandte Trainingswissenschaft, 04109 Leipzig, Germany.
    Grüneberger, René
    Monteverde Bicycles, 10625 Berlin, Germany.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering.
    Modeling optimal cadence as a function of time during maximal sprint exercises can improve performance by elite track cyclists2021Ingår i: Applied Sciences, E-ISSN 2076-3417, Vol. 11, nr 24, artikel-id 12105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In track cycling sprint events, optimal cadence PRopt is a dynamic aspect of fatigue. It is currently unclear what cadence is optimal for an athlete’s performance in sprint races and how it can be calculated. We examined fatigue-induced changes in optimal cadence during a maximal sprint using a mathematical approach. Nine elite track cyclists completed a 6-s high-frequency pedaling test and a 60-s isokinetic all-out sprint on a bicycle ergometer with continuous monitoring of crank force and cadence. Fatigue-free force-velocity (F/v) and power-velocity (P/v) profiles were derived from both tests. The development of fatigue during the 60-s sprint was assessed by fixing the slope of the fatigue-free F/v profile. Fatigue-induced alterations in PRopt were determined by non-linear regression analysis using a mono-exponential equation at constant slope. The study revealed that PRopt at any instant during a 60-s maximal sprint can be estimated accurately using a mono-exponential equation. In an isokinetic mode, a mean PRopt can be identified that enables the athlete to generate the highest mean power output over the course of the effort. Adding the time domain to the fatigue-free F/v and P/v profiles allows time-dependent cycling power to be modelled independent of cadence. 

  • 39.
    Dunst, Anna Katharina
    et al.
    Department of Endurance, Institute for Applied Training Science, Leipzig, Germany.
    Hesse, Clemens
    German Cycling Federation, Frankfurt am Main, Germany.
    Feldmann, Andri
    Department of Movement and Exercise Science, Institute of Sport Science, University of Bern, Switzerland.
    Holmberg, Hans Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, Stockholm, Sweden.
    A Novel Approach to Determining the Alactic Time Span in Connection with Assessment of the Maximal Rate of Lactate Accumulation in Elite Track Cyclists2023Ingår i: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 18, nr 2, s. 157-163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: Following short-term all-out exercise, the maximal rate of glycolysis is frequently assessed on the basis of the maximal rate of lactate accumulation in the blood. Since the end of the interval without significant accumulation (talac) is 1 of 2 denominators in the calculation employed, accurate determination of this parameter is crucial. Although the very existence and definition of talac, as well as the validity of its determination as time-to-peak power (tPpeak), remain controversial, this parameter plays a key role in anaerobic diagnostics. Here, we describe a novel approach to determination of talac and compare it to the current standard. Methods: Twelve elite track cyclists performed 3 maximal sprints (3, 8, and 12 s) and a high-rate, low-resistance pedaling test on an ergometer with monitoring of crank force and pedaling rate. Before and after each sprint, capillary blood samples were taken for determination of lactate accumulation. Fatigue-free force–velocity and power–velocity profiles were generated. talac was determined as tPpeak and as the time point of the first systematic deviation from the force–velocity profile (tFf). Results: Accumulation of lactate after the 3-second sprint was significant (0.58 [0.19] mmol L−1; P < .001, d = 1.982). tFf was <3 seconds and tPpeak was ≥3 seconds during all sprints (P < .001, d = − 2.111). Peak power output was lower than maximal power output (P < .001, d = −0.937). Blood lactate accumulation increased linearly with increasing duration of exercise (R2 ≥ .99) and intercepted the x-axis at ∼tFf. Conclusion: Definition of talac as tPpeak can lead to incorrect conclusions. We propose determination of talac based on tFf, the end of the fatigue-free state that may reflect the beginning of blood lactate accumulation.

  • 40.
    Dunst, Anna Katharina
    et al.
    Department of Endurance Sports, Institute for Applied Training Science, Marschnerstraße 29, Leipzig, 04109, Germany.
    Hesse, Clemens
    German Cycling Federation, Frankfurt am Main, 60528, Germany.
    Ueberschär, Olaf
    Department of Biomechanics, Institute for Applied Training Science, 04109 Leipzig, Germany; Department of Engineering and Industrial Design, Magdeburg-Stendal University of Applied Sciences, Magdeburg, 39114, Germany.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, 17177 Stockholm, Sweden.
    A Novel Approach to the Determination of Time- and Fatigue-Dependent Efficiency during Maximal Cycling Sprints2023Ingår i: Sports, E-ISSN 2075-4663, Vol. 11, nr 2, artikel-id 29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: During maximal cycling sprints, efficiency (η) is determined by the fiber composition of the muscles activated and cadence-dependent power output. To date, due to methodological limitations, it has only been possible to calculate gross efficiency (i.e., the ratio of total mechanical to total metabolic work) in vivo without assessing the impact of cadence and changes during exercise. Eliminating the impact of cadence provides optimal efficiency (ηopt), which can be modeled as a function of time. Here, we explain this concept, demonstrate its calculation, and compare the values obtained to actual data. Furthermore, we hypothesize that the time course of maximal power output (Pmax) reflects time-dependent changes in ηopt. Methods: Twelve elite track cyclists performed four maximal sprints (3, 8, 12, 60 s) and a maximal-pedaling test on a cycle ergometer. Crank force and cadence were monitored continuously to determine fatigue-free force-velocity profiles (F/v) and fatigue-induced changes in Pmax. Respiratory gases were measured during and for 30 min post-exercise. Prior to and following each sprint, lactate in capillary blood was determined to calculate net blood lactate accumulation (ΔBLC). Lactic and alactic energy production were estimated from ΔBLC and the fast component of excess post-exercise oxygen consumption. Aerobic energy production was determined from oxygen uptake during exercise. Metabolic power (MP) was derived from total metabolic energy (WTOT). ηopt was calculated as Pmax divided by MP. Temporal changes in Pmax, WTOT, and ηopt were analyzed by non-linear regression. Results: All models showed excellent quality (R2 > 0.982) and allowed accurate recalculation of time-specific power output and gross efficiency (R2 > 0.986). The time-constant for Pmax(t) (τP) was closely correlated with that of ηopt (τη; r = 0.998, p < 0.001). Estimating efficiency using τP for τη led to a 0.88 ± 0.35% error. Conclusions: Although efficiency depends on pedal force and cadence, the latter influence can be eliminated by ηopt(t) using a mono-exponential equation whose time constant can be estimated from Pmax(t).

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  • 41.
    Dunst, Anna Katharina
    et al.
    Department of Endurance Sports, Institute for Applied Training Science, 04109 Leipzig, Germany.
    Hesse, Clemens
    German Cycling Federation, 60528 Frankfurt, Germany.
    Ueberschär, Olaf
    Department of Biomechanics, Institute for Applied Training Science, 04109 Leipzig, Germany; Department of Engineering and Industrial Design, Magdeburg-Stendal University of Applied Sciences, 39114 Magdeburg, Germany.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, 171 77 Stockholm, Sweden.
    Fatigue-Free Force-Velocity and Power-Velocity Profiles for Elite Track Sprint Cyclists: The Influence of Duration, Gear Ratio and Pedalling Rates2022Ingår i: Sports, E-ISSN 2075-4663, Vol. 10, nr 9, artikel-id 130Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Maximal force-velocity (F/v) profiles for track cyclists are commonly derived from ergometer sprints using an isovelocity or isoinertial approach. Previously, an attempt was made to derive maximal F/v profiles from a single maximal 65-m sprint on the cycling track. Hypothesising that this approach may not accurately reflect the fatigue-free F/v profile, we propose an alternative procedure and compare it to the previous method. Moreover, we test for the impact of gear ratio on diagnostic results.

    Methods: Twelve elite track cyclists completed a high-cadence low-resistance pedalling test on a freestanding roller (motoric test) and two series of three maximal 65-m sprints on a cycling track with different gear ratios. F/v profiles were calculated based on the measured crank force and cadence either during the first 6–7 revolutions (≤6 s) on the track (model I) or were derived from the first 3–4 revolutions (≤3 s) on the track combined with 1 or 2 fatigue-free cycles at cadences above 160 rpm from the motoric test (model II).

    Results: Although both models exhibit high-to-excellent linearity between force and velocity, the extrapolated isometric force was higher (1507.51 ± 257.60 N and 1384.35 ± 276.84 N; p < 0.002; d = 2.555) and the slope steeper (−6.78 ± 1.17 and −5.24 ± 1.11; p < 0.003, d = −2.401) with model I. An ICC of 1.00 indicates excellent model consistency when comparing the F/v profiles (model II) derived from the different geared sprints.

    Conclusions: Assuring fatigue-free measurements and including high-cadence data points in the calculations provide valid maximal F/v and P/v profiles from a single acceleration-sprint independent of gear ratio.

  • 42.
    Düking, Peter
    et al.
    University of Würzburg, Würzburg, Germany.
    Fuss, Franz Konstantin
    Swinburne University of Technology, Melbourne, Australia.
    Holmberg, H. -C
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sperlich, Billy
    University of Würzburg, Germany.
    Recommendations for Assessment of the Reliability, Sensitivity, and Validity of Data Provided by Wearable Sensors Designed for Monitoring Physical Activity2018Ingår i: JMIR mhealth and uhealth, E-ISSN 2291-5222, Vol. 6, nr 4, artikel-id e102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although it is becoming increasingly popular to monitor parameters related to training, recovery, and health with wearable sensor technology (wearables), scientific evaluation of the reliability, sensitivity, and validity of such data is limited and, where available, has involved a wide variety of approaches. To improve the trustworthiness of data collected by wearables and facilitate comparisons, we have outlined recommendations for standardized evaluation. We discuss the wearable devices themselves, as well as experimental and statistical considerations. Adherence to these recommendations should be beneficial not only for the individual, but also for regulatory organizations and insurance companies.

  • 43.
    Düking, Peter
    et al.
    University of Würzburg, Würzburg, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Kunz, Philipp
    University of Würzburg, Würzburg, Germany.
    Leppich, Robert
    University of Würzburg, Würzburg, Germany.
    Sperlich, B.
    University of Würzburg, Würzburg, Germany.
    Intra-individual physiological response of recreational runners to different training mesocycles: a randomized cross-over study2020Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 120, s. 2705-2713Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: Pronounced differences in individual physiological adaptation may occur following various training mesocycles in runners. Here we aimed to assess the individual changes in performance and physiological adaptation of recreational runners performing mesocycles with different intensity, duration and frequency. Methods: Employing a randomized cross-over design, the intra-individual physiological responses [i.e., peak (V ˙ O 2 peak) and submaximal (V ˙ O 2 submax) oxygen uptake, velocity at lactate thresholds (V2, V4)] and performance (time-to-exhaustion (TTE)) of 13 recreational runners who performed three 3-week sessions of high-intensity interval training (HIIT), high-volume low-intensity training (HVLIT) or more but shorter sessions of HVLIT (high-frequency training; HFT) were assessed. Results: V ˙ O 2 submax, V2, V4 and TTE were not altered by HIIT, HVLIT or HFT (p &gt; 0.05). V ˙ O 2 peak improved to the same extent following HVLIT (p = 0.045) and HFT (p = 0.02). The number of moderately negative responders was higher following HIIT (15.4%); and HFT (15.4%) than HVLIT (7.6%). The number of very positive responders was higher following HVLIT (38.5%) than HFT (23%) or HIIT (7.7%). 46% of the runners responded positively to two mesocycles, while 23% did not respond to any. Conclusion: On a group level, none of the interventions altered V ˙ O 2 submax, V2, V4 or TTE, while HVLIT and HFT improved V ˙ O 2 peak. The mean adaptation index indicated similar numbers of positive, negative and non-responders to HIIT, HVLIT and HFT, but more very positive responders to HVLIT than HFT or HIIT. 46% responded positively to two mesocycles, while 23% did not respond to any. These findings indicate that the magnitude of responses to HIIT, HVLIT and HFT is highly individual and no pattern was apparent. 

  • 44.
    Düking, Peter
    et al.
    Julius Maximilians Univ, Wurzburg, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sperlich, Billy
    Julius Maximilians Univ, Wurzburg, Germany.
    Instant biofeedback provided by wearable sensor technology can help to optimize exercise and prevent injury and overuse2017Ingår i: Frontiers in Physiology, E-ISSN 1664-042X, Vol. 8, nr APR, artikel-id 167Artikel i tidskrift (Refereegranskat)
  • 45.
    Düking, Peter
    et al.
    University of Würzburg, Würzburg, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sperlich, Billy
    University of Würzburg, Würzburg, Germany.
    The potential usefulness of virtual reality systems for athletes: A short SWOT analysis2018Ingår i: Frontiers in Physiology, E-ISSN 1664-042X, Vol. 9, nr MAR, artikel-id 128Artikel i tidskrift (Refereegranskat)
  • 46.
    Düking, Peter
    et al.
    Integrative and Experimental Exercise Science, Department of Sport Science, University of Würzburg, Germany.
    Zinner, Christoph
    University of Applied Sciences for Police and Administration of Hesse, Germany.
    Trabelsi, Khaled
    Education, Motricité, Sport et Santé, EM2S, LR19JS01, High Institute of Sport and Physical Education of Sfax, University of Sfax, Tunisia.
    Reed, Jennifer L.
    Exercise Physiology and Cardiovascular Health Laboratory, Division of Cardiac Prevention and Rehabilitation, University of Ottawa Heart Institute, Canada; School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Canada; School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Canada.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa, medicin och rehabilitering. Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, Sweden.
    Kunz, Philipp
    Integrative and Experimental Exercise Science, Department of Sport Science, University of Würzburg, Germany.
    Sperlich, Billy
    Integrative and Experimental Exercise Science, Department of Sport Science, University of Würzburg, Germany.
    Monitoring and adapting endurance training on the basis of heart rate variability monitored by wearable technologies: A systematic review with meta-analysis2021Ingår i: Journal of Science and Medicine in Sport, ISSN 1440-2440, E-ISSN 1878-1861, Vol. 24, nr 11, s. 1180-1192Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Objectives: To systematically perform a meta-analysis of the scientific literature to determine whether the outcomes of endurance training based on heart rate variability (HRV) are more favorable than those of predefined training.

    Design: Systematic review and meta-analysis.

    Methods: PubMed and Web of Science were searched systematically in March of 2020 using keywords related to endurance, the ANS, and training. To compare the outcomes of HRV-guided and predefined training, Hedges' g effect size and associated 95% confidence intervals were calculated.

    Results: A total of 8 studies (198 participants) were identified comprising 9 interventions involving a variety of approaches. Compared to predefined training, most HRV-guided interventions included fewer moderate- and/or high-intensity training sessions. Fixed effects meta-analysis revealed a significant medium-sized positive effect of HRV-guided training on submaximal physiological parameters (g = 0.296, 95% CI 0.031 to 0.562, p = 0.028), but its effects on performance (g = 0.079, 95% CI −0.050 to 0.393, p = 0.597) and V̇O2peak (g = 0.171, 95% CI −0.213 to 0.371, p = 0.130) were small and not statistically significant. Moreover, with regards to performance, HRV-guided training was associated with fewer non-responders and more positive responders.

    Conclusions: In comparison to predefined training, HRV-guided endurance training had a medium-sized effect on submaximal physiological parameters, but only a small and non-significant influence on performance and V̇O2peak. There were fewer non-responders regarding performance with HRV-based training.

  • 47.
    Düking, Peter
    et al.
    University of Würzburg, Würzburg, Germany.
    Zinner, Cristoph
    University of Applied Sciences for Police and Administration of Hesse, Wiesbaden, Germany.
    Reed, Jennifer L.
    University of Ottawa.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Sperlich, Billy
    University of Würzburg, Würzburg, Germany.
    Predefined vs data-guided training prescription based on autonomic nervous system variation: A systematic review2020Ingår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 30, nr 12, s. 2291-2304Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre- and post-intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV-based interventions reduced the amount of moderate- and/or high-intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV-based training. Peak oxygen uptake ((Formula presented.)) and submaximal running parameters (eg, LT1, LT2) improved following both HRV-based and predefined training, with no clear difference in the extent of improvement in (Formula presented.). Submaximal running parameters tended to improve more following HRV-based training. Research findings to date have been limited and inconsistent. Both HRV-based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater. 

  • 48. Ekblom, Björn
    et al.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Eriksson, Kalle
    Dopning inom uthållighetsidrotter [Doping in endurance sports]: Kartläggning av individuell [Hb]-nivå kan avslöja dopning2002Ingår i: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 98, nr 48, s. 5490-5496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Doping through increasing [Hb] increases physical performance in sport. Therefore, no cross-country skiers with [Hb] values above 160 and 175 g/l for women and men, respectively, may start in competitions. Even plasma expanders have been used, possibly for lowering a high [Hb] but this procedure may not increase physical performance. There are methods available for detecting the use of erythropoietin but not reinfusion of erythrocytes to increase [Hb]. To make it more difficult to increase [Hb] by different unethical methods we suggest that the [Hb] in endurance athletes is determined both during the training and the competition season to establish individual [Hb] mean values and range. Since endurance training at altitude does not increase [Hb] after return to sea level, an occasional increased [Hb] is suspicious. In such a case complementary doping tests may be used.

  • 49.
    Ekenros, Linda
    et al.
    Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy, Karolinska Institutet, Alfred Nobels Allé 23, SE-141 83, Huddinge, Sweden.
    von Rosen, Philip
    Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy, Karolinska Institutet, Alfred Nobels Allé 23, SE-141 83, Huddinge, Sweden.
    Norrbom, Jessica
    Department of Physiology and Pharmacology, Molecular Exercise Physiology, Karolinska Institutet, Stockholm, 171 77, Sweden.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. Department of Physiology and Pharmacology, Molecular Exercise Physiology, Karolinska Institutet, Stockholm, 171 77, Sweden.
    Sundberg, Carl Johan
    Department of Physiology and Pharmacology, Molecular Exercise Physiology, Karolinska Institutet, Stockholm, 171 77, Sweden.
    Fridén, Cecilia
    Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy, Karolinska Institutet, Alfred Nobels Allé 23, SE-141 83, Huddinge, Sweden; Department of Women’s and Children’s Health, Karolinska Institutet, 171 76, Stockholm, Sweden; Department of Healthcare and Welfare, Mälardalens University, 721 23, Västerås, Sweden.
    Lindén Hirschberg, Angelica
    Department of Women’s and Children’s Health, Karolinska Institutet, 171 76, Stockholm, Sweden; Department of Gynecology and Reproductive Medicine, Karolinska University Hospital, 171 76, Stockholm, Sweden.
    Impact of Menstrual cycle-based Periodized training on Aerobic performance, a Clinical Trial study protocol—the IMPACT study2024Ingår i: Trials, E-ISSN 1745-6215, Vol. 25, nr 1, artikel-id 93Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: The menstrual cycle and its impact on training and performance are of growing interest. However, evidence is lacking whether periodized exercise based on the menstrual cycle is beneficial. The primary purpose of this proposed randomized, controlled trial, the IMPACT study, is to evaluate the effect of exercise periodization during different phases of the menstrual cycle, i.e., comparing follicular phase-based and luteal phase-based training with regular training during the menstrual cycle on physical performance in well-trained women.

    Methods: Healthy, well-trained, eumenorrheic women between 18 and 35 years (n = 120) will be recruited and first assessed for physical performance during a run-in menstrual cycle at different cycle phases and then randomized to three different interventions: follicular phase-based training, luteal phase-based training, or regular training during three menstrual cycles. The training intervention will consist of high-intensity spinning classes followed by strength training. The menstrual cycle phases will be determined by serum hormone analysis throughout the intervention period. Assessment of aerobic performance (primary outcome) and muscle strength, body composition, and blood markers will be performed at baseline and at the end of the intervention.

    Discussion: With a robust methodology, this study has the potential to provide evidence of the differential effects of exercise periodization during different phases of the menstrual cycle in female athletes.

    Trial registration: ClinicalTrials.gov NCT05697263 . Registered on 25 January 2023

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  • 50.
    Ekenros, Linda
    et al.
    Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy Karolinska Institutet, Huddinge, Sweden.
    von Rosen, Philip
    Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy Karolinska Institutet, Huddinge, Sweden.
    Solli, Guro S
    School of Sport Sciences, UiT, The Arctic University of Norway, Tromsø, Troms, Norway; Department of Sports Science and Physical Education, Nord University, Bodø, Norway.
    Sandbakk, Øyvind
    School of Sport Sciences, UiT, The Arctic University of Norway, Tromsø, Troms, Norway; Department of Neuromedicine and Movement Science, Centre for Elite Sports Research, Norwegian University of Science and Technology, Trondheim, Norway.
    Holmberg, Hans-Christer
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, Hälsa, medicin och rehabilitering. Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, Stockholm, Sweden.
    Hirschberg, Angelica L
    Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden; Department of Gynecology and Reproductive Medicine, Karolinska University Hospital, Stockholm, Sweden.
    Fridén, Cecilia
    Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy Karolinska Institutet, Huddinge, Sweden; Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden; Department of Physiotherapy, School of Health, Care and Social Welfare, Mälardalen University, Västerås, Sweden.
    The perceived influence of menstrual cycle and hormonal contraceptives on training and performance: Comparison between football, handball, and orienteering2023Ingår i: International journal of sports science & coaching, ISSN 1747-9541, E-ISSN 2048-397XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, we published self-reported data concerning the perceived effects of the menstrual cycle and hormonal contraceptives on the training and performance of 1086 female athletes participating in 57 sports. However, studies comparing differences between sports with large sample sizes are lacking. The aim of this ancillary study was to compare the impact of the menstrual cycle and hormonal contraceptives on training and performance between the three largest sports in the cohort, that is, football, handball, and orienteering, as well as the knowledge and support provided to the female athletes engaged in these sports. The results are from a web-based questionnaire completed by 312 football players, 243 handball players, and 93 orienteers. A total of 54% of the orienteers planned their training based on the menstrual cycle, which was a higher proportion compared to football (45%) and handball (29%) players (p < 0.05). Fewer football players believed that the menstrual cycle had an impact on their performance during training and competition compared to the two other sports. A high proportion of the athletes used hormonal contraceptives in all three sports, but a lower proportion of the orienteers (40%) used hormonal contraceptives compared to football (76%) and handball players (66%) (p < 0.05). Football and handball players received overall more support than orienteers, and the support was mostly provided by a physiotherapist and/or a strength and conditioner coach besides the main coach. These findings demonstrate that the perceived influence of the menstrual cycle and hormonal contraceptives on training and performance differs between endurance athletes in orienteering compared to team-sport athletes in football and handball.

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