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  • 1.
    Andersson, Erik
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Supej, Matej
    Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.
    Sandbakk, Oyvind
    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 system2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 110, no 3, p. 585-595Article in journal (Refereed)
    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.

  • 2.
    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 hypoxia2016In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 1, p. 1-10Article in journal (Refereed)
    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.

  • 3. 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 loads2007In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 101, no 5, p. 603-611Article in journal (Refereed)
    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.

  • 4.
    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.

  • 5.
    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 study2020In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 120, p. 2705-2713Article in journal (Refereed)
    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. 

  • 6.
    Hegge, A. M.
    et al.
    Department of Neuroscience, Center for Elite Sports Research, Norwegian University of Science and Technology, Smistadvegen 11, Trondheim, Norway .
    Bucher, E.
    Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland .
    Ettema, G.
    Department of Neuroscience, Center for Elite Sports Research, Norwegian University of Science and Technology, Smistadvegen 11, Trondheim, Norway .
    Faude, O.
    Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland .
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sandbakk, Ø.
    Department of Neuroscience, Center for Elite Sports Research, Norwegian University of Science and Technology, Smistadvegen 11, Trondheim, Norway .
    Gender differences in power production, energetic capacity and efficiency of elite cross-country skiers during whole-body, upper-body, and arm poling2016In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 2, p. 291-300Article in journal (Refereed)
    Abstract [en]

    Purpose: To characterize gender differences in power output, energetic capacity and exercise efficiency during whole-body (WP), upper-body (UP), and arm poling (AP). Methods: Ten male and ten female elite cross-country skiers, matched for international performance level, completed three incremental submaximal tests and a 3-min self-paced performance test on a Concept2 SkiErg. Power output, cardiorespiratory and kinematic variables were monitored. Body composition was determined by dual-energy X-ray absorptiometry. Results: The men demonstrated 87, 97 and 103 % higher power output, and 51, 65 and 71 % higher VO2peak (L min−1) than the women during WP, UP and AP, respectively, while utilizing ~10 % more of their running VO2max in all modes (all P < 0.001). The men had 35, 38 and 59 % more lean mass in the whole body, upper body and arms (all P < 0.001). The men exhibited greater shoulder and elbow extension at the start of poling and greater trunk flexion at the end of poling (all P < 0.05). The relationship between VO2 and power output did not differ between the men and women. Conclusions: Gender differences in power production and peak aerobic capacity increased sequentially from WP to UP to AP, coinciding with a greater portion of the muscle mass in the arms of the men. Although the men and women employed each poling technique differently, the estimated efficiency of double poling was independent of gender.

  • 7. Karlqvist, Lena
    et al.
    Leijon, Ola
    National Institute for Working Life.
    Härenstam, Annika
    National Institute for Working Life.
    Physical demands in working life and individual physical capacity2003In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 89, no 6, p. 536-547Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the prevalence of the excess of metabolic level (metabolic demands in work exceeding one-third of the individual's aerobic capacity) of working men and women today and to describe the population whose metabolic level is exceeded. A second aim was to explore how externally assessed metabolic demands match with the physical function and capacity of working men and women in jobs with the lowest and the highest demands. The aerobic power of each individual (94 men and 94 women) was estimated from heart rate and workload in sub-maximal tests from dynamic legwork on a cycle ergometer. Physical activity was assessed using a task-oriented interview technique. Physical function was measured by tests of muscle endurance in arms, abdomen and legs, handgrip pressure, balance and coordination. The calculation of individual metabolic demands during a "typical working day" showed that 27% of the men and 22% of the women exceeded their metabolic level. The results indicate that the physical fitness is low or somewhat low for two-thirds of the 94 men and for more than one-half of the 94 women. Women in the group with the highest job demands had significantly lower muscle endurance in the abdomen and legs and worse coordination than women in the group with the lowest job demands. Metabolic demands in working life today remain high. This is reflected in a mismatch between individual physical capacity and the physical demands of work for 25% of the population.

  • 8.
    Lindinger, Stefan
    et al.
    Salzburg Univ, Dept Sport Sci & Kinesiol, Christian Doppler Lab Biomech Skiing, A-5020 Salzburg, Austria .
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    How do elite cross-country skiers adapt to different double poling frequencies at low to high speeds?2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 6, p. 1103-1119Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to examine the biomechanical-physiological effects of different frequencies using the double poling technique in cross-country skiing. Nine elite skiers roller-skied using poling frequencies of 40, 60 and 80 cycles·min-1 (Pf40, Pf60, Pf80) at submaximal treadmill speeds (12, 18, 24 km·h-1). Cycle characteristics, pole forces, joint angles and physiological responses were measured. Comparing Pf40 versus Pf60 versus Pf80 (all variables different at P < 0.05), absolute poling time decreased by up to 46%, as did absolute and relative (% cycle time) recovery times, at almost all speeds. Peak force, impulse of force and time to peak force decreased, whereas impact force increased with frequency at almost all speeds. Elbow ranges of motion and angular velocities, hip and knee angle maxima and flexion/extension ranges of motion per cycle decreased, whereas hip and knee angle minima, ranges of motion per minute and angular extension velocities during recovery phase all increased with frequency at nearly all speeds. Oxygen uptake and heart rate increased up to 13% (Pf40-60 versus Pf80) at all speeds. Pulmonary ventilation increased most distinctly at the highest speed. Blood lactate was lowest at Pf60 and highest at Pf80 (J-shape curve) at 24 km·h-1. Gross efficiency decreased with higher frequency at all speeds. These results demonstrate different biomechanical and physiological demands at different frequencies with the beneficial effects of lower poling frequencies at submaximal speeds. For training purposes, we suggest that cross-country skiers would benefit by training with different poling frequencies to vary their training load.

  • 9. 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.

  • 10. Nilsson, Jonny E
    et al.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Tveit, Per
    Hallén, Jostein
    Effects of 20-s and 180-s double poling interval training in cross-country skiers2004In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 92, no 1/2, p. 121-127Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the effect of upper body 20-s or 180-s interval training, using a double poling ergometer, on upper body power output and selected physiological and biomechanical parameters in cross-country skiers. Twenty (12 male, 8 female) well-trained cross-country skiers took part. Two intervention groups, a 20-s interval training group (IT20; n=6) and a 180-s interval training group (IT180; n=7), underwent training three times a week for 6 weeks on a double poling ergometer. A third group served as a control (CON; n=7) and followed the same training program as the IT20 and IT180 groups without the double poling ergometer interval training. The IT20 and IT180 groups significantly (P<0.05) increased both peak and mean power in a 30-s test and mean power in a 6-min test after double poling training. There was a significant improvement in work efficiency in both IT20 and IT180 (P<0.05) and, in IT180, a significant reduction (P<0.05) in blood lactate concentration at given sub-maximal workloads. VO(2peak) increased significantly during double poling in IT180 ( P<0.05) only. VO(2max) did not change significantly in either group. There were no significant changes in any of the test variables in CON. In conclusion, this study shows that 6 weeks of 20-s or 180-s double poling interval training, three times a week, significantly increases power output in both 30-s and 6-min tests, as well as in selected physiological and biomechanical parameters in well-trained cross-country skiers.

  • 11.
    Piedrahita, Hugo
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Oksa, Juha
    Finnish institute of Occupational Health, Physical Work Capacity Team.
    Malm, Christer
    Winternet.
    Sormunen, Erja
    Finnish institute of Occupational Health, Physical Work Capacity Team.
    Rintamäki, Hannu
    Finnish institute of Occupational Health, Physical Work Capacity Team.
    Effects of cooling and clothing on vertical trajectories of the upper arm and muscle functions during repetitive light work2008In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 104, no 2, p. 183-191Article in journal (Refereed)
    Abstract [en]

    The present study was designed to find out if cooling and/or clothing affect the vertical trajectories and muscle function of the upper arm during repetitive light work. Twelve female subjects performed a one-handed lifting task for 60 min while standing in front of a table with six target angles (30 degrees to 220 degrees ). The experiment was carried out in a climatic chamber in three different conditions: at 10 degrees C (C), at 25 degrees C (TN), and at 10 degrees C dressed in cold-protective clothing (C(p)). Skin and rectal temperatures were measured continuously. The vertical trajectories of the head, shoulder, elbow, and wrist on the right side of the body were recorded. Muscular strain (averaged EMG, a-EMG) and EMG gaps in eight muscles on the right upper arm were measured. The variation of the vertical trajectory amplitude of the upper arm measured from the elbow was significantly higher (at 200 degrees ) both at C and C(p) (50 and 25% respectively) and in shoulder (at 220 degrees angle) at C (33%) compared with TN (P < 0.05). Both C and C(p) increased a-EMG and reduced the number and duration of EMG gaps significantly in all muscles studied. In conclusion, in repetitive tasks the high mean vertical trajectory and changes in the amplitude of the trajectory of the upper arm at C and C(p) compared with TN were associated with increased muscular strain and reduced number of EMG gaps (more continuous activation of given muscle fibers). The changes in trajectories may serve as indicator of a risk for local muscle fatigue

  • 12.
    Piedrahita, Hugo
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Oksa, Juha
    Finnish institute of Occupational Health, Physical Work Capacity Team.
    Rintamäki, Hannu
    Finnish institute of Occupational Health, Physical Work Capacity Team.
    Malm, Christer
    Winternet.
    Effect of local leg cooling on upper limb trajectories and muscle function and whole body dynamic balance2009In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, no 3, p. 429-438Article in journal (Refereed)
    Abstract [en]

    This study was designed to find out if local leg cooling affects muscle function and trajectories of the upper limb during repetitive light work as well as capability to maintain dynamic balance. Nine healthy female subjects performed repetitive lifting task with right hand for 60 min while standing in front of a table with six target angles (30°-220°) and with the legs inside a container with 15°C cold water (Cold condition, C) or without water (Normal condition, N). Muscle temperature of the medial aspect of the gastrocnemius, rectal, and skin temperatures were measured continuously. The trajectories of the right upper limb were recorded with a 3D motion analysis system. Muscular strain (averaged EMG, a-EMG) and EMG gaps in eight muscles of the right upper limb were measured. End point excursion depicting the ability to maintain dynamic balance was measured before and after each experiment. Leg cooling decreased significantly (P < 0.05) the muscle and the mean skin temperature in C compared with N (6.7 and 2.2°C, respectively). No marked changes in the trajectories or EMG activity were observed between the different environmental conditions. The end point excursion was significantly (P < 0.05) reduced in C compared with N and a positive correlation between excursion and muscle temperature was found at the end of the working period in C. In conclusion, local leg cooling did not affect upper limb muscle function or trajectories, but ability to maintain dynamic balance was reduced.

  • 13.
    Sandbakk, O.
    et al.
    Department of Human Movement Science, Norwegian University of Science and Technology, Trondheim, 7491, Norway.
    Ettema, G.
    Department of Human Movement Science, Norwegian University of Science and Technology, Trondheim, 7491, Norway.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    The influence of incline and speed on work rate, gross efficiency and kinematics of roller ski skating2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 8, p. 2829-2838Article in journal (Refereed)
    Abstract [en]

    During competitions, elite cross-country skiers produce higher external work rates on uphill than on flat terrain. However, it is not presently known whether this reflects solely higher energy expenditure. Furthermore, the kinematic factors associated with these higher rates of uphill work have not yet been examined. Therefore, in the present investigation the work rate and associated kinematic parameters at similar metabolic rates during roller ski skating on flat and uphill terrains have been compared. Seven elite male skiers performed six 5-min sub-maximal exercise bouts at the same low, moderate and high metabolic rates on 2 and 8% inclines, while roller skiing on a treadmill employing the G3 skating technique. The work rate was calculated as work against gravity and friction, whereas the energetic equivalent of VO2 was taken as the metabolic rate. Gross efficiency was defined as work rate divided by metabolic rate. Kinematic parameters were analyzed in three dimensions. At the same metabolic rate, the work rate, cycle rate, work per cycle and relative duration of propulsive phases during a cycle of movement were all higher on the 8% than on the 2% incline at all speeds (all P &lt; 0.05). At similar work rates, gross efficiency was greater on the 8% incline (P &lt; 0.05). In conclusion, these elite skiers consistently demonstrated higher work rates on the 8% incline. To achieve the higher work rates on the steeper incline, these elite skiers employed higher cycle rates and performed more work per cycle, in association with a longer relative propulsive phase. © 2011 Springer-Verlag.

  • 14.
    Sandbakk, O.
    et al.
    Department of Human Movement Science, Norwegian University of Science and Technology, Trondheim, 7491, Norway.
    Ettema, G.
    Department of Human Movement Science, Norwegian University of Science and Technology, Trondheim, 7491, Norway.
    Leirdal, S.
    Department of Human Movement Science, Norwegian University of Science and Technology, Trondheim, 7491, Norway.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Gender differences in the physiological responses and kinematic behaviour of elite sprint cross-country skiers2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 3, p. 1087-1094Article in journal (Refereed)
    Abstract [en]

    Gender differences in performance by elite endurance athletes, including runners, track cyclists and speed skaters, have been shown to be approximately 12%. The present study was designed to examine gender differences in physiological responses and kinematics associated with sprint cross-country skiing. Eight male and eight female elite sprint cross-country skiers, matched for performance, carried out a submaximal test, a test of maximal aerobic capacity (VO2max) and a shorter test of maximal treadmill speed (Vmax) during treadmill roller skiing utilizing the G3 skating technique. The men attained 17% higher speeds during both the VO2max and the Vmax tests (P &lt; 0.05 in both cases), differences that were reduced to 9% upon normalization for fat-free body mass. Furthermore, the men exhibited 14 and 7% higher VO2max relative to total and fat-free body mass, respectively (P &lt; 0.05 in both cases). The gross efficiency was similar for both gender groups. At the same absolute speed, men employed 11% longer cycles at lower rates, and at peak speed, 21% longer cycle lengths (P &lt; 0.05 in all cases). The current study documents approximately 5% larger gender differences in performance and VO2max than those reported for comparable endurance sports. These differences reflect primarily the higher VO2max and lower percentage of body fat in men, since no gender differences in the ability to convert metabolic rate into work rate and speed were observed. With regards to kinematics, the gender difference in performance was explained by cycle length, not by cycle rate.

  • 15.
    Sandbakk, Oyvind
    et al.
    Department of Human Movement Science, Norwegian University of Science and Technology, 7491 Trondheim, Norway .
    Ettema, Gertjan
    Department of Human Movement Science, Norwegian University of Science and Technology, 7491 Trondheim, Norway .
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    The physiological and biomechanical contributions of poling to roller ski skating2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 8, p. 1979-1987Article in journal (Refereed)
    Abstract [en]

    Poling is considered to make a significant contribution to cross-country skiing with the skating technique. To better understand this contribution, the current investigation compared roller ski skating on a treadmill with the so-called G3 skating technique with (G3-P) and without poling (G3-NP). Seven male elite skiers performed 5-min submaximal tests at 8, 12, and 15 km h(-1), as well as an incremental test to exhaustion with both techniques on a 5 % incline. Ventilatory variables were assessed by open-circuit indirect calorimetry and three-dimensional kinematics analyzed using the Qualisys Pro Reflex system. G3-P was associated with approximately 15 % higher peak velocity and 10 % higher peak oxygen uptake than G3-NP in the incremental test (both P < 0.01). All ventilatory variables, as well as heart rate and blood lactate concentration were lower with G3-P as compared to G3-NP at 12 and 15 km h(-1) (all P < 0.01). Gross efficiency (i.e., the ratio of work rate to metabolic rate) at 12 km h(-1) was higher in G3-P (14.9 %) than G3-NP (13.5 %) (P < 0.01). Moreover, with G3-P cycle time and length were both 30 % longer, with correspondingly reduced cycle rates (all P < 0.01). In addition, the ski gliding and swing phases were longer and the angle between the skis smaller with G3-P (both P < 0.01), whereas the push-off time was independent of technique and velocity. Taken together, these results indicate that poling makes an important contribution to propulsion and velocity during ski skating, specifically by enhancing peak oxygen uptake, skiing efficiency and associated biomechanical variables.

  • 16.
    Sandbakk, Øyvind
    et al.
    Human Movement Science Programme, Norwegian University of Science and Technology.
    Ettema, Gerjan
    Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Leirdal, Stig
    Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Jakobsen, Vidar
    The Norwegian School of Sport Sciences, Oslo, Norway.
    Holmberg, Hans-Christer
    Institutionen för hälsovetenskap, Mittuniversitetet, Sweden.
    Analysis of a sprint ski race and associated laboratory determinants of world-class performance2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 6, p. 947-957Article in journal (Refereed)
    Abstract [en]

    This investigation was designed to analyze the time-trial (STT) in an international cross-country skiing sprint skating competition for (1) overall STT performance and relative contributions of time spent in different sections of terrain, (2) work rate and kinematics on uphill terrain, and (3) relationships to physiological and kinematic parameters while treadmill roller ski skating. Total time and times in nine different sections of terrain by 12 world-class male sprint skiers were determined, along with work rate and kinematics for one specific uphill section. In addition, peak oxygen uptake (VO2peak), gross efficiency (GE), peak speed (Vpeak), and kinematics in skating were measured. Times on the last two uphill and two final flat sections were correlated to overall STT performance (r = ~-0.80, P < 0.001). For the selected uphill section, speed was correlated to cycle length (r = -0.75, P < 0.01) and the estimated work rate was approximately 160% of peak aerobic power. VO2peak, GE, Vpeak, and peak cycle length were all correlated to STT performance (r = ~-0.85, P < 0.001). More specifically, VO2peak and GE were correlated to the last two uphill and two final flat section times, whereas Vpeak and peak cycle length were correlated to times in all uphill, flat, and curved sections except for the initial section (r = ~-0.80, P < 0.01). Performances on uphill and flat terrain in the latter part were the most significant determinants of overall STT performance. Peak oxygen uptake, efficiency, peak speed, and peak cycle length were strongly correlated to overall STT performance, as well as to performance in different sections of the race.

  • 17.
    Sandbakk, Øyvind
    et al.
    Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Holmberg, Hans-Christer
    Institutionen för hälsovetenskap, Mittuniversitetet, Sweden.
    Leirdal, Stig
    Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Ettema, Gertjan
    Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Metabolic Rate and Gross Efficiency at High Work Rates in World Class and National Level Sprint Skiers2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 109, no 3, p. 473-481Article in journal (Refereed)
    Abstract [en]

    The present study investigated metabolic rate (MR) and gross efficiency (GE) at moderate and high work rates, and the relationships to gross kinematics and physical characteristics in elite cross-country skiers. Eight world class (WC) and eight national level (NL) male sprint cross-country skiers performed three 5-min stages using the skating G3 technique, whilst roller skiing on a treadmill. GE was calculated by dividing work rate by MR. Work rate was calculated as the sum of power against gravity and frictional rolling forces. Metabolic rate was calculated using gas exchange and blood lactate values. Gross kinematics, i.e. cycle length (CL) and cycle rate (CR), were measured by video analysis. Furthermore, the skiers were tested for time to exhaustion (TTE), peak oxygen uptake (VO2peak), and maximal speed (Vmax) on the treadmill, and maximal strength in the laboratory. Individual performance level in sprint skating was determined by FIS points. WC skiers did not differ in aerobic MR, but showed lower anaerobic MR and higher GE than NL skiers at a given speed (all P < 0.05). Moreover, WC skiers skated with longer CL and had higher Vmax and TTE (all P < 0.05). In conclusion, the present study shows that WC skiers are more efficient than NL skiers, and it is proposed that this might be due to a better technique and to technique-specific power.

  • 18.
    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.

  • 19.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Zelle, Stefan
    German Research Centre of Elite Sport, Köln, Germany .
    Lochmann, Matthias
    Institute of Sportscience and Sport, University of Nürnberg-Erlangen, Erlangen, Germany .
    Zinner, Christoph
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Holmberg, Hans-Christer
    Institutionen för hälsovetenskap, Mittuniversitetet, Sweden.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    The effects of 6-week-decoupled bi-pedal cycling on submaximal and high intensity performance in competitive cyclists and triathletes2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 8, p. 1625-1630Article in journal (Refereed)
    Abstract [en]

    Aim of this work was to examine the effects of decoupled two-legged cycling on (1) submaximal and maximal oxygen uptake, (2) power output at 4 mmol L-1 blood lactate concentration, (3) mean and peak power output during high intensity cycling (30 s sprint) and (4) isometric and dynamic force production of the knee extensor and flexor muscles. 18 highly trained male competitive male cyclists and triathletes (age 24 ± 3 years; body height 179 ± 11 cm; body mass 78 ± 8 kg; peak oxygen uptake 5,070 ± 680 mL min-1) were equally randomized to exercise on a stationary cycle equipped either with decoupled or with traditional crank system. The intervention involved 1 h training sessions, 5 times per week for 6 weeks at a heart rate corresponding to 70% of VO2peak. VO2 at 100, 140, 180, 220 and 260 and power output at 4 mmol L-1 blood lactate were determined during an incremental test. VO2peak was recorded during a ramp protocol. Mean and peak power output were assessed during a 30 s cycle sprint. The maximal voluntary isometric strength of the quadriceps and biceps femoris muscles was obtained using a training machine equipped with a force sensor. No differences were observed between the groups for changes in any variable (P = 0.15-0.90; effect size = 0.00-0.30). Our results demonstrate that a 6 week (30 sessions) training block using decoupled crank systems does not result in changes in any physiological or performance variables in highly trained competitive cyclists.

  • 20.
    Sperlich, Billy
    et al.
    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.
    Heilemann, Ilka
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Kjendlie, Per-Ludvik
    Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
    Holmberg, Hans-Christer
    Institutionen för hälsovetenskap, Mittuniversitetet, Sweden.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    High-intensity interval training improves VO2peak, maximal lactate accumulation, time trial and competition performance in 9–11-year-old swimmers2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 110, no 5, p. 1029-1036Article in journal (Refereed)
    Abstract [en]

    Training volume in swimming is usually very high when compared to the relatively short competition time. High-intensity interval training (HIIT) has been demonstrated to improve performance in a relatively short training period. The main purpose of the present study was to examine the effects of a 5-week HIIT versus high-volume training (HVT) in 9-11-year-old swimmers on competition performance, 100 and 2,000 m time (T100 m and T2,000 m), VO2peak and rate of maximal lactate accumulation (Lacmax). In a 5-week crossover study, 26 competitive swimmers with a mean (SD) age of 11.5 ± 1.4 years performed a training period of HIIT and HVT. Competition (P < 0.01; effect size = 0.48) and T2,000 m (P = 0.04; effect size = 0.21) performance increased following HIIT. No changes were found in T100 m (P = 0.20). Lacmax increased following HIIT (P < 0.01; effect size = 0.43) and decreased after HVT (P < 0.01; effect size = 0.51). VO2peak increased following both interventions (P < 0.05; effect sizes = 0.46-0.57). The increases in competition performance, T2,000 m, Lacmax and VO2peak following HIIT were achieved in significantly less training time (~2 h/week).

  • 21.
    Sperlich, Billy
    et al.
    Bergische Universität Wuppertal.
    Zinner, Christoph
    German Sport University Cologne.
    Hébert-Losier, Kim
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Born, Dennis-Peter
    Bergische Universität Wuppertal.
    Holmberg, Hans-Christer
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Biomechanical, cardiorespiratory, metabolic and perceived responses to electrically assisted cycling.2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 12, p. 4015-4025Article in journal (Refereed)
    Abstract [en]

    The aims of the present study were to characterize the effects of cycling in varying terrain with the assistance of an electric motor with respect to (1) power output, velocity, and electromyography (EMG) signals; (2) cardiorespiratory parameters; (3) energy expenditure (EE); (4) rate of perceived exertion (RPE) and enjoyment and to compare these effects with those of non-assisted cycling. Eight sedentary women (age: 38 ± 15 years, BMI: 25.3 ± 2.1 kg m(-2)) cycled 9.5 km on varying terrain (change in elevation: 102 m, maximum incline: 5.8 %) at their own pace, once with and once without motorized assistance, in randomized order. With electrical assistance, the mean power output (-29 %); EMG patterns of the m. biceps femoris (-49 %), m. vastus lateralis (-33 %), m. vastus medialis (-37 %), and m. gastrocnemius medialis (-29 %); heart rate (-29.1 %); oxygen uptake (-33.0 %); respiratory exchange ratio (-9.0 %); and EE (-36.5 %) were all lower, whereas the mean cycling speed was higher (P < 0.05) than that without such assistance. In addition, following assisted exercise the mean blood lactate concentration and RPE were lower (P < 0.05) and ratings of enjoyment higher (P < 0.05). Moreover, motorized cycling was associated with (1) lower EMG with higher power output and speed; (2) less cardiorespiratory and metabolic effort; (3) lower respiratory exchange ratio; (4) lower RPE with more enjoyment; and (5) sufficient EE, according to present standards, to provide health benefits. Thus, electrically assisted cycling may represent an innovative approach to persuading reluctant sedentary women to exercise.

  • 22.
    Sperlich, Billy
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Zinner, Christoph
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Pfister, Roman
    Univ Cologne, Dept Internal Med 3, D-50937 Cologne, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Michels, Guido
    Univ Cologne, Dept Internal Med 3, D-50937 Cologne, Germany.
    Repeated apnea-induced contraction of the spleen in cyclists does not enhance performance in a subsequent time-trial2015In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 115, no 1, p. 205-212Article in journal (Refereed)
    Abstract [en]

    Splenic contraction induced by repeated apneas has been shown to increase oxygen availability. Our aim was to determine whether repeated maximal voluntary apnea enhances the performance of cyclists in a subsequent 4-km time trial. Seven male cyclists [age: 27.1 +/- A 2.1 years; height: 182 +/- A 8 cm; body mass: 74.8 +/- A 9.2 kg; peak oxygen uptake: 56.9 +/- A 6.6 mL min(-1) kg(-1) (mean +/- A SD)] performed a 4-km time trial on an ergometer with and without four prior maximal bouts of apnea interspersed with 2 min of recovery. The average power output during the time trial was similar with (293 +/- A 48 W) and without (305 +/- A 42 W) prior apnea (P = 0.11, d = 0.27). The spleen was reduced in size after the fourth bout of apnea (-12.4 +/- A 9.0 %), as well as one (-36.6 +/- A 10.3 %) and 10 min (-19.5 +/- A 17.9 %) after the time trial, while with normal breathing the spleen was smaller one (-35.0 +/- A 11.3 %) and 10 min (-23.4 +/- A 19.7 %) after the time trial. Heart rate; oxygen uptake and carbon dioxide production; tissue oxygen saturation; and the lactate concentration, pH, oxygen saturation, level of hemoglobin and hematocrit of the blood were similar under both conditions. Our present findings reveal that four apneas by cyclists prior to a 4-km time trial led to splenic contraction, but no change in mean power output, the level of hemoglobin, hematocrit, oxygen saturation of the m. vastus lateralis or oxygen uptake.

  • 23.
    Zinner, Christoph
    et al.
    Univ Wurzburg, Dept Sport Sci, Integrat & Expt Training Sci, Judenbhulweg 11, D-97082 Wurzburg, Germany.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sperlich, Billy
    Univ Wurzburg, Dept Sport Sci, Integrat & Expt Training Sci, Judenbhulweg 11, D-97082 Wurzburg, Germany.
    Topical application of cream containing nonivamide and nicoboxil does not enhance the performance of experienced cyclists during a 4-km time-trial2016In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 5, p. 969-974Article in journal (Refereed)
    Abstract [en]

    Topical application of nonivamide-nicoboxil cream to resting legs has been shown to enhance the level of oxygenated haemoglobin in leg muscles 15 min later. Here, we examined whether such application improves the performance of experienced cyclists in a subsequent 4-km time-trial. Nine male cyclists [26 +/- A 8 years; 176 +/- A 9 cm; 73.5 +/- A 12.8 kg; peak oxygen uptake: 50.7 +/- A 4.0 mL min(-1) kg(-1) (mean +/- A SD)] performed three 4-km time-trials on an ergometer with either topical application of nonivamide-nicoboxil cream (CREAM) or cream without active components (SHAM) to both their thigh muscles or no application (CONTROL). Only the skin temperature immediately before and after the time-trial was higher with cream than SHAM and CONTROL (best p < 0.001, best d = 1.16). All other parameters evaluated, i.e., the average power output during the time-trial (p > 0.05, best d = 0.08), the tissue saturation index of the m. vastus lateralis (p > 0.05, best d = 0.57), cardiac output, heart rate, oxygen uptake, blood lactate concentration, and perceived exertion (p > 0.05, best d = 1.1) were similar under all three conditions. Our present findings reveal that topical application of cream containing nonivamide and nicoboxil to the thighs of cyclists prior to a 4-km time-trial does not improve their power output, saturation of the m. vastus lateralis with oxygen, oxygen uptake, heart rate, cardiac parameters, or perceived level of exertion.

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