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  • 1.
    Al-Husseini, Ali
    et al.
    Department of Clinical Sciences Lund, Neurosurgery, Skåne University Hospital, Lund University, Lund, Sweden.
    Gard, Anna
    Department of Clinical Sciences Lund, Neurosurgery, Skåne University Hospital, Lund University, Lund, Sweden.
    Fransson, Per-Anders
    Department of Clinical Sciences, Lund University, Lund, Sweden.
    Tegner, Yelverton
    Luleå University of Technology, Department of Health, Learning and Technology, Health, Medicine and Rehabilitation.
    Magnusson, Måns
    Department of Clinical Sciences, Lund University, Lund, Sweden.
    Marklund, Niklas
    Department of Clinical Sciences Lund, Neurosurgery, Skåne University Hospital, Lund University, Lund, Sweden.
    Tjernström, Fredrik
    Department of Clinical Sciences, Lund University, Lund, Sweden.
    Long-term postural control in elite athletes following mild traumatic brain injury2022In: Frontiers in Neurology, E-ISSN 1664-2295, Vol. 13, article id 906594Article in journal (Refereed)
    Abstract [en]

    Background: Traumas to the head and neck are common in sports and often affects otherwise healthy young individuals. Sports-related concussions (SRC), defined as a mild traumatic brain injury (mTBI), may inflict persistent neck and shoulder pain, and headache, but also more complex symptoms, such as imbalance, dizziness, and visual disturbances. These more complex symptoms are difficult to identify with standard health care diagnostic procedures.

    Objective: To investigate postural control in a group of former elite athletes with persistent post-concussive symptoms (PPCS) at least 6 months after the incident.

    Method: Postural control was examined using posturography during quiet stance and randomized balance perturbations with eyes open and eyes closed. Randomized balance perturbations were used to examine motor learning through sensorimotor adaptation. Force platform recordings were converted to reflect the energy used to maintain balance and spectrally categorized into total energy used, energy used for smooth corrective changes of posture (i.e., <0.1 Hz), and energy used for fast corrective movements to maintain balance (i.e., >0.1 Hz).

    Results: The mTBI group included 20 (13 males, mean age 26.6 years) elite athletes with PPCS and the control group included 12 athletes (9 males, mean age 26.4 years) with no history of SRC. The mTBI group used significantly more energy during balance perturbations than controls: +143% total energy, p = 0.004; +122% low frequency energy, p = 0.007; and +162% high frequency energy, p = 0.004. The mTBI subjects also adapted less to the balance perturbations than controls in total (18% mTBI vs. 37% controls, p = 0.042), low frequency (24% mTBI vs. 42% controls, p = 0.046), and high frequency (6% mTBI vs. 28% controls, p = 0.040). The mTBI subjects used significantly more energy during quiet stance than controls: +128% total energy, p = 0.034; +136% low-frequency energy, p = 0.048; and +109% high-frequency energy, p = 0.015.

    Conclusion: Athletes with previous mTBI and PPCS used more energy to stand compared to controls during balance perturbations and quiet stance and had diminished sensorimotor adaptation. Sports-related concussions are able to affect postural control and motor learning.

  • 2.
    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?2010In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 24, p. lb273-Article in journal (Refereed)
    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

     

  • 3.
    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 females2014In: PLOS ONE, E-ISSN 1932-6203, Vol. 5, no 9, article id e112079Article in journal (Refereed)
    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.

  • 4.
    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 leg2010In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 42, no 10, p. 1899-1908Article in journal (Refereed)
    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.

  • 5.
    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 mechanisms2014In: BMC Sports Science, Medicine and Rehabilitation, E-ISSN 2052-1847, Vol. 6, no 21Article in journal (Refereed)
    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.

  • 6.
    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 exercise2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 6, p. 905-913Article in journal (Refereed)
    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.

  • 7.
    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 University of Technology, Department of Health, Learning and Technology, Health, Medicine and Rehabilitation. 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 Rates2022In: Sports, E-ISSN 2075-4663, Vol. 10, no 9, article id 130Article in journal (Refereed)
    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.

  • 8.
    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 Strøm
    School of Sport Sciences, UiT, the Arctic University of Norway, Tromsø, 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, Norway; Department of Neuromedicine and Movement Science, Centre for Elite Sports Research, Norwegian University of Science and Technology, Trondheim, Norway.
    Holmberg, Hans-Christer
    Luleå University of Technology, Department of Health, Learning and Technology, Health, Medicine and Rehabilitation. Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institutet, Stockholm, Sweden.
    Hirschberg, Angelica Lindén
    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.
    Perceived impact of the menstrual cycle and hormonal contraceptives on physical exercise and performance in 1,086 athletes from 57 sports2022In: Frontiers in Physiology, E-ISSN 1664-042X, Vol. 13, article id 954760Article in journal (Refereed)
    Abstract [en]

    Female athletes train and compete under the potential influence of hormonal fluctuations during the menstrual cycle or during use of various hormonal contraceptives. Dysmenorrhea and premenstrual symptoms are common in the general population, as well as side effects of hormonal contraceptives. More detailed knowledge concerning prevalence and perceived impact of these symptoms on training and performance in different sports is required. The aim of the study was to 1) characterize perceptions of training and performance during the menstrual cycle phases and by hormonal contraceptive use in a large population of female athletes; 2) explore whether symptoms experienced are related to perceived performance; and 3) examine potential differences in these factors between athletes at different levels of performance. The study was based on self-reported data from 1,086 athletes from 57 sports at different performance levels via a web-based questionnaire. Thirty-seven percent (n = 407) of the athletes did not use hormonal contraceptives. In this group, menstrual cycle related symptoms were common across all athlete levels, particularly dysmenorrhea (74%, n = 300) and premenstrual symptoms (78%, n = 318), which also influenced perceived performance of aerobic fitness, muscle strength, mental sharpness, balance, and sleep quality. Sixty-three percent (n = 679) of the athletes used various hormonal contraceptives and 40% (n = 272) perceived a variety of side-effects. Physical performance was experienced equally independent of time-point of the pill-chart except for the period of inactive pills, which was associated with more negative impact. Nonetheless, only 18% (n = 191) of the athletes considered menstrual cycle or hormonal contraceptive issues when planning their training or competitions. These results indicate that greater focus is needed to identify and effectively treat different menstrual cycle and hormonal contraceptive related symptoms on an individual level.

  • 9.
    Galvan-Alvarez, Victor
    et al.
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Gallego-Selles, Angel
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Martinez-Canton, Miriam
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    García-Gonzalez, Eduardo
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Gelabert-Rebato, Miriam
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Ponce-Gonzalez, Jesus Gustavo
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain.
    Larsen, Steen
    Center of Healthy Ageing, Department of Biomedical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark; Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland.
    Morales-Alamo, David
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Losa-Reyna, Jose
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain.
    Perez-Suarez, Ismael
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Dorado, Cecilia
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Perez-Valera, Mario
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Holmberg, Hans-Christer
    Luleå University of Technology, Department of Health, Learning and Technology, Health, Medicine and Rehabilitation. School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada.
    Boushel, Robert
    School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada.
    de Pablos Velasco, Pedro
    Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain; Department of Endocrinology and Nutrition, Hospital Universitario de Gran Canaria Doctor Negrin, Las Palmas de Gran Canaria, Spain.
    Helge, Jorn Wulff
    Center of Healthy Ageing, Department of Biomedical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark.
    Martin-Rincon, Marcos
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Calbet, Jose A.L.
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain; School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada; Department of Physical Performance, The Norwegian School of Sport Sciences, Postboks, 4014 Ulleval Stadion, 0806, Oslo, Norway.
    Antioxidant enzymes and Nrf2/Keap1 in human skeletal muscle: Influence of age, sex, adiposity and aerobic fitness2023In: Free Radical Biology & Medicine, ISSN 0891-5849, E-ISSN 1873-4596, Vol. 209, no Part 2, p. 282-291Article in journal (Refereed)
    Abstract [en]

    Whether a higher aerobic fitness is associated with increased expression of antioxidant enzymes and their regulatory factors in skeletal muscle remains unknown. Although oestrogens could promote a higher antioxidant capacity in females, it remains unknown whether a sex dimorphism exists in humans regarding the antioxidant capacity of skeletal muscle. Thus, the aim was to determine the protein expression levels of the antioxidant enzymes SOD1, SOD2, catalase and glutathione reductase (GR) and their regulatory factors Nrf2 and Keap1 in 189 volunteers (120 males and 69 females) to establish whether sex differences exist and how age, VO2max and adiposity influence these. For this purpose, vastus lateralis muscle biopsies were obtained in all participants under resting and unstressed conditions. No significant sex differences in Nrf2, Keap1, SOD1, SOD2, catalase and GR protein expression levels were observed after accounting for VO2max, age and adiposity differences. Multiple regression analysis indicates that the VO2max in mL.kg LLM−1.min−1can be predicted from the levels of SOD2, Total Nrf2 and Keap1 (R = 0.58, P < 0.001), with SOD2 being the main predictor explaining 28 % of variance in VO2max, while Nrf2 and Keap1 explained each around 3 % of the variance. SOD1 protein expression increased with ageing in the whole group after accounting for differences in VO2max and body fat percentage. Overweight and obesity were associated with increased pSer40-Nrf2, pSer40-Nrf2/Total Nrf2 ratio and SOD1 protein expression levels after accounting for differences in age and VO2max. Overall, at the population level, higher aerobic fitness is associated with increased basal expression of muscle antioxidant enzymes, which may explain some of the benefits of regular exercise.

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  • 10.
    Galvan-Alvarez, Victor
    et al.
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Martin-Rincon, Marcos
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Gallego-Selles, Angel
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Martínez Canton, Miriam
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    HamedChaman, NaDer
    Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain; Department of Exercise Physiology, Faculty of Sports Sciences, University of Mazandaran, Babolsar, Mazandaran, Iran.
    Gelabert-Rebato, Miriam
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Perez-Valera, Mario
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    García-Gonzalez, Eduardo
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain.
    Santana, Alfredo
    Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain; Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Clinical Genetics Unit, 35016, Las Palmas de Gran Canaria, Spain.
    Holmberg, Hans-Christer
    Luleå University of Technology, Department of Health, Learning and Technology, Health, Medicine and Rehabilitation. School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada.
    Boushel, Robert
    School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada.
    Hallén, Jostein
    Department of Physical Performance, The Norwegian School of Sport Sciences, Postboks, 4014 Ulleval Stadion, 0806, Oslo, Norway.
    Calbet, Jose A.L.
    Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe “Fisico” s/n, 35017, Las Palmas de Gran Canaria, Spain; School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada; Department of Physical Performance, The Norwegian School of Sport Sciences, Postboks, 4014 Ulleval Stadion, 0806, Oslo, Norway.
    Determinants of the maximal functional reserve during repeated supramaximal exercise by humans: The roles of Nrf2/Keap1, antioxidant proteins, muscle phenotype and oxygenation2023In: Redox Biology, E-ISSN 2213-2317, Vol. 66, article id 102859Article in journal (Refereed)
    Abstract [en]

    When high-intensity exercise is performed until exhaustion a “functional reserve” (FR) or capacity to produce power at the same level or higher than reached at exhaustion exists at task failure, which could be related to reactive oxygen and nitrogen species (RONS)-sensing and counteracting mechanisms. Nonetheless, the magnitude of this FR remains unknown. Repeated bouts of supramaximal exercise at 120% of VO2max interspaced with 20s recovery periods with full ischaemia were used to determine the maximal FR. Then, we determined which muscle phenotypic features could account for the variability in functional reserve in humans. Exercise performance, cardiorespiratory variables, oxygen deficit, and brain and muscle oxygenation (near-infrared spectroscopy) were measured, and resting muscle biopsies were obtained from 43 young healthy adults (30 males). Males and females had similar aerobic (VO2max per kg of lower extremities lean mass (LLM): 166.7 ± 17.1 and 166.1 ± 15.6 ml kg LLM−1.min−1, P = 0.84) and anaerobic fitness (similar performance in the Wingate test and maximal accumulated oxygen deficit when normalized to LLM). The maximal FR was similar in males and females when normalized to LLM (1.84 ± 0.50 and 2.05 ± 0.59 kJ kg LLM−1, in males and females, respectively, P = 0.218). This FR depends on an obligatory component relying on a reserve in glycolytic capacity and a putative component generated by oxidative phosphorylation. The aerobic component depends on brain oxygenation and phenotypic features of the skeletal muscles implicated in calcium handling (SERCA1 and 2 protein expression), oxygen transport and diffusion (myoglobin) and redox regulation (Keap1). The glycolytic component can be predicted by the protein expression levels of pSer40-Nrf2, the maximal accumulated oxygen deficit and the protein expression levels of SOD1. Thus, an increased capacity to modulate the expression of antioxidant proteins involved in RONS handling and calcium homeostasis may be critical for performance during high-intensity exercise in humans.

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  • 11.
    Gejl, Kasper D.
    et al.
    Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, Denmark.
    Ørtenblad, Niels
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Andersson, Erik
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Plomgaard, Peter
    Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Nielsen, Joachim
    Department of Pathology, SDU Muscle Research Cluster, Odense University Hospital, Odense.
    Local depletion of glycogen with supra-maximal exercise in human skeletal muscle fibres2017In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 595, no 9, p. 2809-2821Article in journal (Refereed)
    Abstract [en]

    Skeletal muscle glycogen is heterogeneous distributed in three separated compartments (intramyofibrillar, intermyofibrillar and subsarcolemmal). Although only constituting 4-15% of the total glycogen volume, the availability of intramyofibrillar glycogen has been shown to be of particular importance to muscle function. The present study was designed to investigate the depletion of these three sub-cellular glycogen compartments during repeated supra-maximal exercise in elite athletes. Ten elite cross-country skiers (age: 25 +/- 4 yrs., VO2 max : 65 +/- 4 ml kg-1 min-1 , mean +/- SD) performed four approximately 4-minute supra-maximal sprint time trials (STT 1-4) with 45 min recovery. The sub-cellular glycogen volumes in m. triceps brachii were quantified from electron microscopy images before and after both STT 1 and STT 4. During STT 1, the depletion of intramyofibrillar glycogen was higher in type I fibres (-52% [-89:-15%]) than type 2 fibres (-15% [-52:22%]) (P = 0.02), while the depletion of intermyofibrillar glycogen (main effect: -19% [-33:0], P = 0.006) and subsarcolemmal glycogen (main effect: -35% [-66:0%], P = 0.03) was similar between fibre types. In contrast, only intermyofibrillar glycogen volume was significantly reduced during STT 4, in both fibre types (main effect: -31% [-50:-11%], P = 0.002). Furthermore, for each of the sub-cellular compartments, the depletion of glycogen during STT 1 was associated with the volumes of glycogen before STT 1. In conclusion, the depletion of spatially distinct glycogen compartments differs during supra-maximal exercise. Furthermore, the depletion changes with repeated exercise and is fibre type-dependent. 

  • 12.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    The elite cross-country skier provides unique insights into human exercise physiology2015In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 25, no S4, p. 100-109Article, review/survey (Refereed)
    Abstract [en]

    Successful cross-country skiing, one of the most demanding of endurance sports, involves considerable physiological challenges posed by the combined upper- and lower-body effort of varying intensity and duration, on hilly terrain, often at moderate altitude and in a cold environment. Over the years, this unique sport has helped physiologists gain novel insights into the limits of human performance and regulatory capacity. There is a long-standing tradition of researchers in this field working together with coaches and athletes to improve training routines, monitor progress, and refine skiing techniques. This review summarizes research on elite cross-country skiers, with special emphasis on the studies initiated by Professor Bengt Saltin. He often employed exercise as a means to learn more about the human body, successfully engaging elite endurance athletes to improve our understanding of the demands, characteristics, and specific effects associated with different types of exercise.

  • 13.
    Kehler, Alyse
    et al.
    Univ Colorado, Dept Integrat Physiol, Boulder, CO 80309 USA.
    Hajkova, E
    Univ Colorado, Dept Integrat Physiol, Boulder, CO 80309 USA.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Kram, Rodger
    Univ Colorado, Dept Integrat Physiol, Boulder, CO 80309 USA.
    Forces and mechanical energy fluctuations during diagonal stride roller skiing; running on wheels?2014In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 217, no 21, p. 3779-3785Article in journal (Refereed)
    Abstract [en]

    Mechanical energy can be conserved during terrestrial locomotion in two ways: the inverted pendulum mechanism for walking and the spring-mass mechanism for running. Here, we investigated whether diagonal stride cross-country roller skiing (DIA) utilizes similar mechanisms. Based on previous studies, we hypothesized that running and DIA would share similar phase relationships and magnitudes of kinetic energy (KE), and gravitational potential energy (GPE) fluctuations, indicating elastic energy storage and return, as if roller skiing is like 'running on wheels'. Experienced skiers (N=9) walked and ran at 1.25 and 3 m s(-1), respectively, and roller skied with DIA at both speeds on a level dual-belt treadmill that recorded perpendicular and parallel forces. We calculated the KE and GPE of the center of mass from the force recordings. As expected, the KE and GPE fluctuated with an out-of-phase pattern during walking and an in-phase pattern during running. Unlike walking, during DIA, the KE and GPE fluctuations were in phase, as they are in running. However, during the glide phase, KE was dissipated as frictional heat and could not be stored elastically in the tendons, as in running. Elastic energy storage and return epitomize running and thus we reject our hypothesis. Diagonal stride cross-country skiing is a biomechanically unique movement that only superficially resembles walking or running.

  • 14. Lindinger, Stefan J
    et al.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Mueller, Erich
    Rapp, Walter
    Changes in upper body muscle activity with increasing double poling velocities in elite cross-country skiing2009In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 106, no 3, p. 353-363Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate whether the stretch-shortening cycle (SSC) contraction is integrated in neuromuscular activation in upper body muscles during double poling in cross-country skiing. Thirteen elite skiers performed double poling roller-skiing at increasing treadmill velocities of 9, 15, 21, 27 km h(-1) and their individual maximal velocity. Elbow angle, axial pole force and surface EMG in the triceps brachii, pectoralis major, latissimus dorsi and teres major muscle were recorded. Increases in peak pole force, rate of force development and elbow flexion angular velocities were identified (P < 0.05). The mean MVC-normalized EMG amplitudes increased during the pre-activation phase before pole plant, elbow flexion and the reflex-mediated phase between 30 and 120 ms after pole plant due to velocity increases (P < 0.05). It is thus suggested that elite cross-country skiers use SSC during double poling, particularly in the triceps muscle in order to generate high forces.

  • 15.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, Stockholm.
    Apró, William
    Swedish School of Sport and Health Sciences, Stockholm.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, Stockholm.
    Van Hall, Gerrit
    University of Copenhagen, Copenhagen, Denmark.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, Stockholm; Karolinska Institutet, Stockholm.
    Activation of mTORC1 by leucine is potentiated by branched-chain amino acids and even more so by essential amino acids following resistance exercise2016In: American Journal of Physiology - Cell Physiology, ISSN 0363-6143, E-ISSN 1522-1563, Vol. 310, no 11, p. C874-C884Article in journal (Refereed)
    Abstract [en]

    Protein synthesis is stimulated by resistance exercise and intake of amino acids, in particular leucine. Moreover, activation of mammalian target of rapamycin complex 1 (mTORC1) signaling by leucine is potentiated by the presence of other essential amino acids (EAA). However, the contribution of the branched-chain amino acids (BCAA) to this effect is yet unknown. Here we compare the stimulatory role of leucine, BCAA, and EAA ingestion on anabolic signaling following exercise. Accordingly, eight trained volunteers completed four sessions of resistance exercise during which they ingested either placebo, leucine, BCAA, or EAA (including the BCAA) in random order. Muscle biopsies were taken at rest, immediately after exercise, and following 90 and 180 min of recovery. Following 90 min of recovery the activity of S6 kinase 1 (S6K1) was greater than at rest in all four trials (Placebo&lt;Leucine&lt;BCAA&lt;EAA; P &lt; 0.05 time × supplement), with a ninefold increase in the EAA trial. At this same time point, phosphorylation of eukaryotic translation initiation factor 4E (eIF4E)- binding protein 1 (4E-BP1) at Thr37/46 was unaffected by supplementation, while that of Thr46 alone exhibited a pattern similar to that of S6K1, being 18% higher with EAA than BCAA. However, after 180 min of recovery this difference between EAA and BCAA had disappeared, although with both these supplements the increases were still higher than with leucine (40%, P &lt; 0.05) and placebo (100%, P &lt; 0.05). In summary, EAA ingestion appears to stimulate translation initiation more effectively than the other supplements, although the results also suggest that this effect is primarily attributable to the BCAA.

  • 16.
    Schulte, Stefanie
    et al.
    Institute of Motor Control and Movement Technique, German Sport University Cologne, Cologne, Germany.
    Schiffer, Thorsten
    Institute of Motor Control and Movement Technique, German Sport University Cologne, Cologne, Germany.
    Sperlich, Billy
    Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany.
    Kleinöder, Heinz
    Institute of Training Science and Sport Informatics, German Sport University Cologne, Cologne, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Serum Concentrations of S100B are not Affected by Cycling to Exhaustion With or Without Vibration2011In: Journal of Human Kinetics, ISSN 1640-5544, E-ISSN 1899-7562, Vol. 30, no 1, p. 67-78Article in journal (Refereed)
    Abstract [en]

    The calcium-binding protein S100B is produced primarily by astrocytes and exerts concentration-dependentparacrine and autocrine effects on neurons and glia. The numerous findings of a correlation between S100B andtraumatic brain injury (TBI) have resulted in the employment of this protein as a clinical biomarker for such injury.Our present aim was to determine whether cycling with (V) or without (NV) vibration alters serum concentrations ofS100B. Twelve healthy, male non-smokers (age: 25.3±1.6 yrs, body mass: 74.2±5.9 kg, body height: 181.0±3.7 cm,VO2peak: 56.9±5.1 ml·min-1·kg-1(means ± SD)) completed in random order two separate trials to exhaustion on avibrating bicycle (amplitude 4 mm and frequency 20 Hz) connected to an ergometer. The initial workload of 100 W waselevated by 50 W every 5 min and the mean maximal period of exercise was 25:27±1:30 min. The S100B in venousblood taken at rest, immediately after the test, and 30, 60 and 240 min post-exercise exhibited no significant differences(p>0.05), suggesting that cycling with and without vibration does not influence this parameter.

  • 17.
    Sperlich, Billy
    et al.
    Department of Sport Science, University of Wuppertal, Wuppertal, Germany.
    Achtzehn, S
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Buhr, M
    Institute of Health Promotion and Clinical Movement Science, Köln, Germany.
    Zinner, C
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Zelle, S
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Holmberg, Hans-Christer
    Institutionen för hälsovetenskap, Mittuniversitetet, Sweden.
    Salivary Cortisol, Heart Rate and Blood Lactate Responses During Elite Downhill Mountain Bike Racing2012In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 7, no 1, p. 47-52Article, review/survey (Refereed)
    Abstract [en]

    Purpose: This study aimed to quantify the intensity profile of elite downhill mountain bike races during competitions. Methods: Seventeen maledownhill racers (22 ± 5 y; 185.1 ± 5.3 cm; 68.0 ± 3.9 kg; VO 2peak: 59.4 ± 4.1 mL min kg -1) participated in the International German DownhillChampionships in 2010. The racers' peak oxygen uptake and heart rate (HR) at 2 and 4 mmol L -1 blood lactate (HR2 and HR 4), were assessed during an incremental laboratory step test (100 W, increase 40 W every 5 min). During the races, the HR was recorded and pre- and postrace bloodlactate concentrations as well as salivary cortisol levels were obtained. Results: During the race, the absolute time spent in the "easy" intensity zone was 23.3 ± 6.8 s, 24.2 ± 12.8 s (HR 2-HR 4) in the "moderate" zone, and 151.6 ± 18.3 s (>HR 4) in the "hard" zone. Eighty percent of the entire race was accomplished at intensities >90% HRpeak. Blood lactate concentrations postrace were higher than those obtained after the qualification heat (8.0 ± 2.5 mmol L -1 vs 6.7 ± 1.8 mmol L -1, P < .01). Salivary levels of cortisol before the competition and the qualification heat were twice as high as at resting state (P < .01). Conclusions: This study shows that mountain bike downhill races are conducted at high heart rates and levels of blood lactate as well as increased concentration of salivary cortisol as marker for psycho-physiological stress. © 2011 Human Kinetics, Inc.

  • 18.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Haegele, Matthias
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Krueger, Malte
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Schiffer, Thorsten
    Outpatient Clinic for Sports Traumatology and Public Health Consultation, German Sport University Köln, Köln, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Cardio-respiratory and metabolic responses to different levels of compression during submaximal exercise2011In: Phlebology, ISSN 0268-3555, E-ISSN 1758-1125, Vol. 26, no 3, p. 102-106Article in journal (Refereed)
    Abstract [en]

    Objective: The effects of knee-high socks that applied different levels of compression (0, 10, 20, 30 and 40 mmHg) on various cardio-respiratory and metabolic parameters during submaximal running were analysed. Methods: Fifteen well-trained, male endurance athletes (age: 22.2 +/- 1.3 years; peak oxygen uptake: 57.2 +/- 4.0 mL/minute/kg) performed a ramp test to determine peak oxygen uptake. Thereafter, all athletes carried out five periods of submaximal running (at approximately 70% of peak oxygen uptake) with and without compression socks that applied the different levels of pressure. Cardiac output and index, stroke volume, arteriovenous difference in oxygen saturation, oxygen uptake, arterial oxygen saturation, heart rate and blood lactate were monitored before and during all of these tests. Results: Cardiac output (P = 0.29) and index (P = 0.27), stroke volume (P = 0.50), arteriovenous difference in oxygen saturation (P = 0.11), oxygen uptake (P = 1.00), arterial oxygen saturation (P = 1.00), heart rate (P = 1.00) and arterial lactate concentration (P = 1.00) were unaffected by compression (effect sizes = 0.00-0.65). Conclusion: This first evaluation of the potential effects of increasing levels of compression on cardio-respiratory and metabolic parameters during submaximal exercise revealed no effects whatsoever.

  • 19.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Haegle, Mathias
    German Research Centre of Elite Sport, Am Sportpark Müngersdorf, 50933 Köln, Germany.
    Achtzehn, Silvia
    German Research Centre of Elite Sport, Am Sportpark Müngersdorf, 50933 Köln, Germany.
    Linville, John
    University of Nebraska at Omaha, Omaha, Nebraska, USA.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes2010In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 28, no 6, p. 609-614Article in journal (Refereed)
    Abstract [en]

    The effects of three textiles with increasing compressive surface were compared with non-compressive conventional clothing on physiological and perceptual variables during sub-maximal and maximal running. 15 well-trained endurance athletes (mean ± s, age: 27.1 ± 4.8 years, VO2max 63.7 ± 4.9 ml∙min-1∙kg-1) performed four sub-maximal (~70%VO2max) and maximal tests with and without different compression stockings, tights, and whole body compression suits. Arterial lactate concentration, oxygen saturation and partial pressure, pH, oxygen uptake and ratings of muscle soreness were recorded before, during, and after all tests. Additionally, time to exhaustion was assessed. Sub-maximal (P = 0.22) and maximal oxygen uptake (P = 0.26), arterial lactate concentration (P = 0.16; 0.20), pH (P = 0.23; 0.46), oxygen saturation (P = 0.13; 0.26) and oxygen partial pressure (P = 0.09; 0.20) did not differ between the types of clothing (effect sizes = 0.00-0.45). Ratings of perceived exertion (P = 0.10; 0.15), muscle soreness (P = 0.09; 0.10) and time to exhaustion (P = 0.16) were also unaffected by the different clothing (effect sizes = 0.28-0.85). For the first time, the effect on endurance performance of different types of compression clothing with increasing amount of compressive surface was evaluated. Overall, there were no performance benefits when using the compression garments.

  • 20.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Holmberg, Hans-Christer
    Institutionen för hälsovetenskap, Mittuniversitetet, Sweden.
    Physiological effects of a new racing suit for elite cross country skiers2011In: Journal of Sports Medicine and Physical Fitness, ISSN 0022-4707, E-ISSN 1827-1928, Vol. 51, no 4, p. 555-559Article in journal (Refereed)
    Abstract [en]

    AIM: The aim of this paper was to investigate the influence of the new cross country racing suit, designed for the Olympic Winter Games in Vancouver 2010, on cardio-respiratory, thermoregulatory and perceptual responses.METHODS: Six elite cross country skiers (29±6 years, peak oxygen uptake 73.2±6.9 mL·min-1·kg-1) performed two exercise bouts wearing either the 2009 or the 2010 racing suit. Bouts consisted of incremental testing on roller skis (12 km·h-1 at 5° inclination; 11 km·h-1 at 6° inclination and 12 km·h-1at 8° inclination for six minutes).RESULTS: During increasing intensities, significantly lower values were found for oxygen uptake, minute ventilation, RER and heart rate when wearing the new suit compared to the old one (P<0.05; effect sizes: 0.21-4.00). Core temperature was lower with the new suit during steps 2 and 3 (P<0.05, effect size: 1.22-1.27). Also, mean skin temperature was lower during the last increment (P<0.05, effect size: 0.87).CONCLUSION:The new 2010 racing suit, developed specifically for the Olympic Winter Games in Vancouver 2010, demonstrated lower values for oxygen uptake, minute ventilation, heart rate, skin and core temperature, ratings of thermal and sweat sensation when compared to the 2009 racing suit.

  • 21.
    Sperlich, Billy
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Osman-Reinkens, S
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Zinner, Christoph
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Krueger, M
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Cardiorespiratory, metabolic and hormonal responses during open-wheel indoor kart racing2014In: Journal of Sports Medicine and Physical Fitness, ISSN 0022-4707, E-ISSN 1827-1928, Vol. 54, no 4, p. 475-480Article in journal (Refereed)
    Abstract [en]

    AIM: This study aimed to quantify the cardiorespiratory, metabolic and hormonal responses of elite open-wheel indoor kart racers.METHODS: Ten male racers (age: 21±3 yrs; height: 1.92±0.06 m, body mass: 76.0±5.9 kg) participated in a racing tournament. Their peak oxygen uptake and heart rate were assessed by a ramp test (100 W, increase 30 W·min-1) in the laboratory. During the racing itself, the cardio-respiratory and accelerometer values were recorded and pre- and post-race levels of blood lactate and salivary cortisol were determined.RESULTS: The average peak values for all of the drivers with respect to oxygen uptake and heart rate were 4.5±0.8 L·min-1 (56.7±7.9 mL·min-1·kg-1) and 193±5 beats·min-1, respectively. Overall, 28.3±3.3 laps were completed during 30-min of racing. Acceleration forces for the entire test averaged 1.20±0.51 G (maximum: 3.30 G), declining from the first 10 min until the end of racing (P<0.03). The oxygen uptake (~20 mL·min-1·kg-1), heart rate (~133 beats·min-1), respiratory exchange ratio (~0.96) and ventilation (~70 L·min-1) observed indicated moderate cardio-respiratory responses. Blood lactate concentration was significantly higher after the race than before but remained at <2 mmol·L-1 (P<0.01; effect size: 1.62).CONCLUSION: There were no differences between salivary cortisol levels before and after the race (P<0.06; effect size: 0.49). Directly after the race, the drivers rated their perceived exertion on Borg’s scale as 11.1±1.3. The present data revealed that the psycho-physical exertion associated with a 30-min open-wheel indoor kart race is moderate.

  • 22.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Schiffer, Thorsten
    Outpatient Clinic for Sports Traumatology and Public Health Consultation, Köln, Germany.
    Achtzehn, Silvia
    German Research Centre of Elite Sport, Am Sportpark Müngersdorf, 50933 Köln, Germany.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Pre-exposure to hyperoxic air does not enhance power output during subsequent sprint cycling2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 110, no 2, p. 301-305Article in journal (Refereed)
    Abstract [en]

    Previous studies have indicated that aerobic pathways contribute to 13-27% of the energy consumed during short-term (10-20-second) sprinting exercise. Accordingly, the present investigation was designed to test the hypothesis that prior breathing of oxygen-enriched air (FinO2=60%) would enhance power output and reduce fatigue during subsequent sprint cycling. Ten well-trained male cyclists (mean ± SD, age: 25±3 years, height: 186.1±6.9 cm, body mass: 79.1±8.2 kg, maximal oxygen uptake [VO2max]: 63.2±5.2 ml·kg-1·min-1) took 25 breaths of either hyperoxic (HE) or normoxic (NO) air before performing 15 sec of cycling at maximal exertion. During this performance, the maximal and mean power outputs were recorded. The concentration of lactate, pH, partial pressure of and saturation by oxygen, [H+] and base excess in arterial blood were assessed before and after the sprint. The maximal (1053±141 W for HE versus 1052±165 W for NO; P = 0.77) and mean power outputs (873±123 versus 876±147 W; P = 0.68) did not differ between the two conditions. The partial pressure of oxygen was approximately 2.3-fold higher after inhaling HE in comparison to NO, while lactate concentration, pH, [H+] and base excess (best P = 0.32) after sprinting were not influenced by exposure to HE. These findings suggest that the peak and mean power outputs of athletes performing short-term intense exercise cannot be improved by pre-exposure to oxygen-enriched air.

  • 23.
    Ørtenblad, Niels
    et al.
    University of Southern Denmark, Odense, Denmark.
    Nielsen, Joachim
    University of Southern Denmark, Odense, Denmark.
    Saltin, Bengt
    Copenhagen Muscle Research Centre, Copenhagen, Denmark.
    Holmberg, Hans-Christer
    Institutionen för hälsovetenskap, Mittuniversitetet, Sweden.
    Role of glycogen availability in sarcoplasmic reticulum Ca(2+) kinetics in human skeletal muscle2011In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 589, no 3, p. 711-725Article in journal (Refereed)
    Abstract [en]

    Little is known about the precise mechanism that relates skeletal muscle glycogen to muscle fatigue. The aim of the present study was to examine the effect of glycogen on sarcoplasmic reticulum (SR) function in the arm and leg muscles of elite cross-country skiers (n = 10, (V) over dot(O2 max) 72 +/- 2 ml kg(-1) min(-1)) before, immediately after, and 4 h and 22 h after a fatiguing 1 h ski race. During the first 4 h recovery, skiers received either water or carbohydrate (CHO) and thereafter all received CHO-enriched food. Immediately after the race, arm glycogen was reduced to 31 +/- 4% and SR Ca2+ release rate decreased to 85 +/- 2% of initial levels. Glycogen noticeably recovered after 4 h recovery with CHO (59 +/- 5% initial) and the SR Ca2+ release rate returned to pre-exercise levels. However, in the absence of CHO during the first 4 h recovery, glycogen and the SR Ca2+ release rate remained unchanged (29 +/- 2% and 77 +/- 8%, respectively), with both parameters becoming normal after the remaining 18 h recovery with CHO. Leg muscle glycogen decreased to a lesser extent (71 +/- 10% initial), with no effects on the SR Ca2+ release rate. Interestingly, transmission electron microscopy (TEM) analysis revealed that the specific pool of intramyofibrillar glycogen, representing 10-15% of total glycogen, was highly significantly correlated with the SR Ca2+ release rate. These observations strongly indicate that low glycogen and especially intramyofibrillar glycogen, as suggested by TEM, modulate the SR Ca2+ release rate in highly trained subjects. Thus, low glycogen during exercise may contribute to fatigue by causing a decreased SR Ca2+ release rate.

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