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  • 1.
    Andersson, Erik
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Ørtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Metabolic responses and pacing strategies during successive sprint skiing time trials2016In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, no 12, p. 2544-2554Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To examine the metabolic responses and pacing strategies during the performance of successive sprint time trials (STTs) in cross-country skiing. METHODS: Ten well-trained male cross-country skiers performed four self-paced 1300-m STTs on a treadmill, each separated by 45 min of recovery. The simulated STT course was divided into three flat (1°) sections (S1, S3 and S5) involving the double poling sub-technique interspersed with two uphill (7°) sections (S2 and S4) involving the diagonal stride sub-technique. Treadmill velocity and V˙O2 were monitored continuously and gross efficiency was used to estimate the anaerobic energy supply. RESULTS: The individual trial-to-trial variability in STT performance time was 1.3%, where variations in O2 deficit and V˙O2 explained 69% (P < 0.05) and 11% (P > 0.05) of the variation in performance. The first and last STTs were equally fast (228 ± 10 s), and ~ 1.3% faster than the second and the third STTs (P < 0.05). These two fastest STTs were associated with a 14% greater O2 deficit (P < 0.05), while the average V˙O2 was similar during all four STTs (86 ± 3% of V˙O2max). Positive pacing was used throughout all STTs, with significantly less time spent on the first than second course half. In addition, metabolic rates were substantially higher (~_30%) for uphill than for flat skiing, indicating that pacing was regulated to the terrain. CONCLUSIONS: The fastest STTs were characterized primarily by a greater anaerobic energy production, which also explained 69% of the individual variation in performance. Moreover, the skiers employed positive pacing and a variable exercise intensity according to the course profile, yielding an irregular distribution of anaerobic energy production.

  • 2.
    Apró, William
    et al.
    Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Amino Acid-induced S6K1 Activity in Human Skeletal Muscle is Mediated By Increased mTor/Rheb Interaction: 128 June 1, 11: 15 AM - 11: 30 AM2016In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, no 5 Suppl 1, p. 17-Article in journal (Refereed)
    Abstract [en]

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

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

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

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

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

  • 3.
    Bakker, Emily
    et al.
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Engan, Harald
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Patrician, Alexander
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Karlsen, Trine
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Wisloff, Ulrik
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Gaustad, Svein Erik
    Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway.
    Effects Of Dietary Nitrate Supplementation On Endothelial Function At High Altitude2014In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 46, no 5, p. 424-424Article in journal (Other academic)
  • 4. Berg, H.E
    et al.
    Eiken, O
    Tesch, P.A
    Involvment of eccentric muscle actions in gaint slalom racing1995In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 27, no 12, p. 1666-1670Article in journal (Refereed)
  • 5.
    Björklund, Glenn
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Stöggl, Thomas
    Department of Sport Science and Kinesiology, University of Salzburg, Austria.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 6.
    Cotter, Joshua A.
    et al.
    Univ Calif Irvine, Irvine, CA USA .
    Hoang, Theresa
    Univ Calif Irvine, Irvine, CA USA .
    Yu, Alvin
    Univ Calif Irvine, Irvine, CA USA .
    Tesch, Per
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Caiozzo, Vincent J.
    Univ Calif Irvine, Irvine, CA USA .
    Adams, Gregory R.
    Univ Calif Irvine, Irvine, CA USA .
    Counteracting Decrements in Muscle Function and Aerobic Capacity During Unloading Utilizing a Gravity Independent Device2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no Suppl 2, p. 110-110Article in journal (Other academic)
  • 7.
    Danielsen, Jorgen
    et al.
    Norwegian Univ Sci & Technol, Dept Neurosci, Ctr Elite Sports Res, N-7489 Trondheim, Norway..
    Sandbakk, Oyvind
    Norwegian Univ Sci & Technol, Dept Neurosci, Ctr Elite Sports Res, N-7489 Trondheim, Norway..
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Ettema, Gertjan
    Norwegian Univ Sci & Technol, Dept Neurosci, Ctr Elite Sports Res, N-7489 Trondheim, Norway.
    Mechanical Energy and Propulsion in Ergometer Double Poling by Cross-country Skiers2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 12, p. 2586-2594Article in journal (Refereed)
    Abstract [en]

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

  • 8.
    Diment, Bethany
    et al.
    Bangor University, UK.
    Fortes, Matthew B
    Bangor University, UK.
    Edwards, Jason P
    Bangor University, UK.
    Hanstock, Helen
    Bangor University, UK.
    Ward, Mark D
    Bangor University, UK.
    Dunstall, Huw M
    Bangor University, UK.
    Friedmann, Peter S
    University of Southampton, UK.
    Walsh, Neil P
    Bangor University, UK.
    Exercise Intensity and Duration Effects on In Vivo Immunity2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 7, p. 1390-1398Article in journal (Refereed)
    Abstract [en]

    Purpose: To examine the effects of intensity and duration of exercise stress on induction of in vivo immunity in humans using experimental contact hypersensitivity (CHS) with the novel antigen diphenylcyclopropenone (DPCP).Methods: Sixty-four healthy males completed either 30 min running at 60% V˙O2peak (30MI), 30 min running at 80% V˙O2peak (30HI), 120 min running at 60% V˙O2peak (120MI), or seated rest (CON). Twenty min later, the subjects received a sensitizing dose of DPCP; and 4 wk later, the strength of immune reactivity was quantified by measuring the cutaneous responses to a low dose-series challenge with DPCP on the upper inner arm. Circulating epinephrine, norepinephrine and cortisol were measured before, after, and 1 h after exercise or CON. Next, to understand better whether the decrease in CHS response on 120MI was due to local inflammatory or T-cell-mediated processes, in a crossover design, 11 healthy males performed 120MI and CON, and cutaneous responses to a dose series of the irritant, croton oil (CO), were assessed on the upper inner arm.Results: Immune induction by DPCP was impaired by 120MI (skinfold thickness -67% vs CON; P < 0.05). However, immune induction was unaffected by 30MI and 30HI despite elevated circulating catecholamines (30HI vs pre: P < 0.01) and greater circulating cortisol post 30HI (vs CON; P < 0.01). There was no effect of 120MI on skin irritant responses to CO.Conclusions: Prolonged moderate-intensity exercise, but not short-lasting high- or short-lasting moderate-intensity exercise, decreases the induction of in vivo immunity. No effect of prolonged moderate-intensity exercise on the skin's response to irritant challenge points toward a suppression of cell-mediated immunity in the observed decrease in CHS. Diphenylcyclopropenone provides an attractive tool to assess the effect of exercise on in vivo immunity.

  • 9.
    Elmer, Steven
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Barratt, Paul R.
    Korff, Thomas
    Martin, James C.
    Joint-specific power production during submaximal and maximal cycling2011In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 43, p. 1940-1947Article in journal (Refereed)
  • 10.
    Elmer, Steven
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Danvind, Jonas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Development of a novel eccentric arm cycle ergometer for training the upper body2013In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 45, no 1, p. 206-211Article in journal (Refereed)
    Abstract [en]

    Several investigators have demonstrated that chronic eccentric leg cycling is an effective method for improving lower body neuromuscular function (e.g., quadriceps muscle size, strength, and mobility) in a variety of patient and athletic populations. To date, there are no reports of using eccentricarm cycling (ECarm) as an exercise modality, probably in large part because of the lack of commercially available ECarm ergometers. Purpose: Our purposes for conducting this study were to 1) describe the design and construction of an ECarm ergometer and 2) compare ECarm to traditional concentric arm cycling (CCarm). Methods: All of the parts of a Monark 891E cycle ergometer (Monark Exercise AB, Vansbro, Sweden) were removed, leaving the frame and flywheel. An electric motor (2.2 kW) was connected to the flywheel via a pulley and a belt. Motor speed and pedaling rate were controlled by a variable frequency drive. A power meter quantified power and pedaling rate, and provided feedback to the individual. Eight individuals performed 3-min ECarm and CCarm trials at 40, 80, and 120 W (60 rpm) while V̇O2 was measured. Results: The ECarm ergometer was simple to use, was adjustable, provided feedback on power output to the user, and allowed for a range of eccentric powers. V̇O2 during ECarm was substantially lower compared with CCarm (P < 0.001). At similar V̇O2 (0.97 ± 0.18 vs 0.91 ± 0.09 L•min, for ECarm and CCarm, respectively, P = 0.26), power absorbed during ECarm was approximately threefold greater than that produced during CCarm (118 ± 1 vs 40 ± 1 W, P < 0.001). Conclusion: This novel ECarm ergometer can be used to perform repetitive, high-force, multijoint, eccentric actions with the upper body at a low level of metabolic demand and may allow researchers and clinicians to use ECarm as a training and rehabilitation modality. © 2012 by the American College of Sports Medicine.

  • 11.
    Elmer, Steven
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Marshall, C S
    Univ Utah, Dept Exercise & Sport Sci, Salt Lake City, UT USA.
    Wehmanen, K
    Univ Utah, Dept Exercise & Sport Sci, Salt Lake City, UT USA.
    Amann, M
    Univ Utah, Dept Internal Med, Salt Lake City, UT 84112 USA.
    McDaniel, J
    Kent State Univ, Dept Exercise Sci, Kent, OH 44242 USA.
    Martin, D
    Australian Inst Sport, Dept Physiol, Canberra, ACT, Australia.
    Martin, J
    Univ Utah, Dept Exercise & Sport Sci, Salt Lake City, UT USA.
    Effects of Locomotor Muscle Fatigue on Joint-specific Power Production During Cycling2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no 8, p. 1504-1511Article in journal (Refereed)
    Abstract [en]

    ABSTRACT: Previous authors have reported reductions in maximum power after high-intensity cycling exercise. Exercise-induced changes in power produced by ankle, knee, and hip joint actions (joint-specific powers), however, have not been reported. PURPOSE: To evaluate joint-specific power production during a cycling time trial (TT) and also compare pre- to post-TT changes in maximal cycling (MAXcyc) joint-specific powers. METHODS: Ten cyclists performed MAXcyc trials (90rpm) before and after a 10min TT (28810W, 90rpm). Pedal forces and limb kinematics were determined with a force-sensing pedal and an instrumented spatial linkage, respectively. Joint-specific powers were calculated and averaged over complete pedal cycles and over extension and flexion phases. RESULTS: Pedal and joint-specific powers did not change during the TT. Pedal power produced during post-TT MAXcyc was reduced by 323% (P<0.001) relative to pre-TT. Relative changes in ankle plantar flexion (435%) and knee flexion powers (525%) were similar but were greater than changes in knee extension (124%) and hip extension powers (286%) (both P<0.05). Pedal and joint-specific powers produced during post-TT MAXcyc were greater than those powers produced during the final 3s of the TT (P<0.01). CONCLUSION: Exercise-induced changes in MAXcyc power manifested with differential power loss at each joint action with ankle plantar flexion and knee flexion exhibiting relatively greater fatigue than knee extension and hip extension. However, changes in MAXcyc joint-specific powers were not presaged by changes in TT joint-specific powers. We conclude that fatigue induced via high-intensity cycling does not alter submaximal joint-specific powers but has distinct functional consequences for MAXcyc joint-specific powers

  • 12.
    Elmer, Steven
    et al.
    Department of Exercise and Sport Science, the University of Utah, Salt Lake City, UT.
    Martin, James C.
    Joint-specific power loss after eccentric exercise2010In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 42, p. 1723-1730Article in journal (Refereed)
  • 13.
    Faiss, R.
    et al.
    Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.
    Willis, Sarah
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Born, D. -P
    Department of Sport Science, University of Wuppertal, Wuppertal, Germany.
    Sperlich, B.
    Department of Sport Science, University of Wuppertal, Wuppertal, Germany.
    Vesin, J. -M
    Applied Signal Processing Group, Swiss Federal Institute of Technology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland .
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Millet, G. P.
    Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland .
    Repeated double-poling sprint training in hypoxia by competitive cross-country skiers2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 4, p. 809-817Article in journal (Refereed)
    Abstract [en]

    Purpose: Repeated-sprint training in hypoxia (RSH) was recently shown to improve repeated-sprint ability (RSA) in cycling. This phenomenon is likely to reflect fiber type-dependent, compensatory vasodilation, and therefore, our hypothesis was that RSH is even more beneficial for activities involving upper body muscles, such as double poling during cross-country skiing. Methods: In a double-blinded fashion, 17 competitive cross-country skiers performed six sessions of repeated sprints (each consisting of four sets of five 10-s sprints, with 20-s intervals of recovery) either in normoxia (RSN, 300 m; FiO2, 20.9%; n = 8) or normobaric hypoxia (RSH, 3000 m; FiO2, 13.8 %; n = 9). Before (pre) and after (post) training, performance was evaluated with an RSA test (10-s all-out sprints-20-s recovery, until peak power output declined by 30%) and a simulated team sprint (team sprint, 3×3-min all-out with 3-min rest) on a double-poling ergometer. Triceps brachii oxygenation was measured by near-infrared spectroscopy. Results: From pretraining to posttraining, peak power output in the RSA was increased (P < 0.01) to the same extent (29% ± 13% vs 26% ± 18%, nonsignificant) in RSH and in RSN whereas the number of sprints performed was enhanced in RSH (10.9 ± 5.2 vs 17.1 ± 6.8, P < 0.01) but not in RSN (11.6 T 5.3 vs 11.7 ± 4.3, nonsignificant). In addition, the amplitude in total hemoglobin variations during sprints throughout RSA rose more in RSH (P < 0.01). Similarly, the average power output during all team sprints improved by 11% T 9% in RSH and 15% T 7% in RSN. Conclusions: Our findings reveal greater improvement in the performance of repeated double-poling sprints, together with larger variations in the perfusion of upper body muscles in RSH compared with those in RSN. © 2014 by the American College of Sports Medicine.

  • 14.
    Faiss, Raphael
    et al.
    Univ Lausanne, Fac Biol & Med, Inst Sport Sci, Lausanne, Switzerland.;Univ Lausanne, Fac Biol & Med, Dept Physiol, Lausanne, Switzerland..
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Millet, Gregoire P.
    Univ Lausanne, Fac Biol & Med, Inst Sport Sci, Lausanne, Switzerland.;Univ Lausanne, Fac Biol & Med, Dept Physiol, Lausanne, Switzerland..
    Enhanced Performance after Repeated Sprint Training in Hypoxia: False or Reality? Response2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 11, p. 2484-2484Article in journal (Other academic)
  • 15.
    Fernandez-Gonzalo, Rodrigo
    et al.
    Karolinska Inst, Stockholm, Sweden.
    Lundberg, Tommy R.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Tesch, Per A.
    Karolinska Inst, Stockholm, Sweden.
    Gene Expression After Acute Resistance Exercise is Modified by Aerobic Exercise and Chronic Training2013In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 45, no 5, p. 528-528Article in journal (Other academic)
  • 16.
    Garvican-Lewis, Laura A.
    et al.
    Australian Catholic Univ, Mary Mackillop Inst Hlth Res, Melbourne, Vic, Australia; Australian Inst Sport, Canberra, ACT, Australia.
    Vuong, Victor L.
    Australian Inst Sport, Canberra, ACT, Australia.
    Govus, Andrew D.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Peeling, Peter
    Western Australian Inst Sport, Perth, WA, Australia; Univ Western Australia, Sch Human Sci Exercise & Sports Sci, Perth, WA, Australia.
    Jung, Grace
    Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Los Angeles, CA, USA.
    Nemeth, Elizabeta
    Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Los Angeles, CA, USA.
    Hughes, David
    Australian Inst Sport, Canberra, ACT, Australia.
    Lovell, Greg
    Australian Inst Sport, Canberra, ACT, Australia.
    Eichner, Daniel
    Sports Med Res & Testing Lab, Salt Lake City, UT USA.
    Gore, Christopher J.
    Australian Inst Sport, Canberra, ACT, Australia.
    Intravenous Iron Does Not Augment the Hemoglobin Mass Response to Simulated Hypoxia2018In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 50, no 8, p. 1669-1678Article in journal (Refereed)
    Abstract [en]

    Purpose Iron is integral for erythropoietic adaptation to hypoxia, yet the importance of supplementary iron compared with existing stores is poorly understood. The aim of the present study was to compare the magnitude of the hemoglobin mass (Hb(mass)) in response to altitude in athletes with intravenous (IV), oral, or placebo iron supplementation. Methods Thirty-four, nonanemic, endurance-trained athletes completed 3 wk of simulated altitude (3000 m, 14 hd(-1)), receiving two to three bolus iron injections (ferric carboxymaltose), daily oral iron supplementation (ferrous sulfate), or a placebo, commencing 2 wk before and throughout altitude exposure. Hb(mass) and markers of iron regulation were assessed at baseline (day -14), immediately before (day 0), weekly during (days 8 and 15), and immediately, 1, 3, and 6 wk after (days 22, 28, 42, and 63) the completion of altitude exposure. Results Hb(mass) significantly increased after altitude exposure in athletes with IV (mean % [90% confidence interval (CI)], 3.7% [2.8-4.7]) and oral (3.2% [2.2-4.2]) supplementation and remained elevated at 7 d postaltitude in oral (2.9% [1.5-4.3]) and 21 d after in IV (3.0% [1.5-4.6]) supplementation. Hb(mass) was not significantly higher than baseline at any time point in placebo. Conclusions Iron supplementation appears necessary for optimal erythropoietic adaptation to altitude exposure. IV iron supplementation during 3 wk of simulated live high-train low altitude training offered no additional benefit in terms of the magnitude of the erythropoietic response for nonanemic endurance athletes compared with oral supplementation.

  • 17.
    Gejl, K. D.
    et al.
    Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark .
    Hvid, L. G.
    Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark .
    Frandsen, U.
    Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark .
    Jensen, Kurt
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark .
    Sahlin, K.
    Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden .
    Ørtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark .
    Muscle glycogen content modifies SR Ca2+ release rate in elite endurance athletes2014In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 46, no 3, p. 496-505Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of the present study was to investigate the influence of muscle glycogen content on sarcoplasmic reticulum (SR) function and peak power output (Wpeak) in elite endurance athletes. Methods: Fourteen highly trained male triathletes (V̇O2max = 66.5 ± 1.3 mL O2·kg·min), performed 4 h of glycogen-depleting cycling exercise (HRmean = 73% ± 1% of maximum). During the first 4 h of recovery, athletes received either water (H2O) or carbohydrate (CHO), separating alterations in muscle glycogen content from acute changes affecting SR function and performance. Thereafter, all subjects received CHO-enriched food for the remaining 20-h recovery period. Results: Immediately after exercise, muscle glycogen content and SR Ca release rate was reduced to 32% ± 4% (225 ± 28 mmol·kg dw) and 86% ± 2% of initial levels, respectively (P < 0.01). Glycogen markedly recovered after 4 h of recovery with CHO (61% ± 2% of preexercise) and SR Ca release rate returned to preexercise level. However, in the absence of CHO during the first 4 h of recovery, glycogen and SR Ca release rate remained depressed, with the normalization of both parameters at the end of the 24 h of recovery after receiving a CHO-enriched diet. Linear regression demonstrated a significant correlation between SR Ca release rate and muscle glycogen content (P < 0.01, r = 0.30). The 4 h of cycling exercise reduced Wpeak by 5.5%-8.9% at different cadences (P < 0.05), and Wpeak was normalized after 4 h of recovery with CHO, whereas Wpeak remained depressed (P < 0.05) after water provision. Wpeak was fully recovered after 24 h in both the H2O and the CHO group. Conclusion: In conclusion, the present results suggest that low muscle glycogen depresses muscle SR Ca release rate, which may contribute to fatigue and delayed recovery of Wpeak 4 h postexercise. © 2014 by the American College of Sports Medicine.

  • 18.
    Gejl, Kasper Degn
    et al.
    Univ Southern Denmark, Dept Sports Sci & Clin Biomech, Odense M, Denmark.
    Thams, Line Bork
    Univ Southern Denmark, Dept Sports Sci & Clin Biomech, Odense M, Denmark.
    Hansen, Mette
    Aarhus Univ, Sect Sport Sci, Dept Publ Hlth, Aarhus, Denmark.
    Rokkedal-Lausch, Torben
    Aalborg Univ, Dept Hlth Sci & Technol, SMI, Fac Med, Aalborg, Denmark.
    Plomgaard, Peter
    Rigshosp, Dept Clin Biochem, Copenhagen, Denmark; Univ Copenhagen, Dept Infect Dis, Ctr Phys Act Res, Rigshosp, Copenhagen, Denmark.
    Nybo, Lars
    Univ Copenhagen, Dept Nutr Exercise & Sports, Copenhagen, Denmark.
    Larsen, Filip J.
    Karolinska Inst, Dept Physiol & Pharmacol, Stockholm; Swedish Sch Sport & Hlth Sci, Stockholm.
    Cardinale, Daniele A.
    Swedish Sch Sport & Hlth Sci, Stockholm; Swedish Sports Confederat, Elite Performance Ctr, Stockholm.
    Jensen, Kurt
    Univ Southern Denmark, Dept Sports Sci & Clin Biomech, Odense M, Denmark.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Olymp Comm, Stockholm.
    Vissing, Kristian
    Aarhus Univ, Sect Sport Sci, Dept Publ Hlth, Aarhus, Denmark.
    Ørtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Univ Southern Denmark, Dept Sports Sci & Clin Biomech, Odense M, Denmark.
    No Superior Adaptations to Carbohydrate Periodization in Elite Endurance Athletes2017In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 49, no 12, p. 2486-2497Article in journal (Refereed)
    Abstract [en]

    Purpose The present study investigated the effects of periodic carbohydrate (CHO) restriction on endurance performance and metabolic markers in elite endurance athletes. Methods Twenty-six male elite endurance athletes (maximal oxygen consumption (VO2max), 65.0 mL O(2)kg(-1)min(-1)) completed 4 wk of regular endurance training while being matched and randomized into two groups training with (low) or without (high) CHO manipulation 3 dwk(-1). The CHO manipulation days consisted of a 1-h high-intensity bike session in the morning, recovery for 7 h while consuming isocaloric diets containing either high CHO (414 2.4 g) or low CHO (79.5 1.0 g), and a 2-h moderate bike session in the afternoon with or without CHO. VO2max, maximal fat oxidation, and power output during a 30-min time trial (TT) were determined before and after the training period. The TT was undertaken after 90 min of intermittent exercise with CHO provision before the training period and both CHO and placebo after the training period. Muscle biopsies were analyzed for glycogen, citrate synthase (CS) and -hydroxyacyl-coenzyme A dehydrogenase (HAD) activity, carnitine palmitoyltransferase (CPT1b), and phosphorylated acetyl-CoA carboxylase (pACC). Results The training effects were similar in both groups for all parameters. On average, VO2max and power output during the 30-min TT increased by 5% +/- 1% (P < 0.05) and TT performance was similar after CHO and placebo during the preload phase. Training promoted overall increases in glycogen content (18% +/- 5%), CS activity (11% +/- 5%), and pACC (38% +/- 19%; P < 0.05) with no differences between groups. HAD activity and CPT1b protein content remained unchanged. Conclusions Superimposing periodic CHO restriction to 4 wk of regular endurance training had no superior effects on performance and muscle adaptations in elite endurance athletes.

  • 19.
    Gerber, Markus
    et al.
    Univ Basel, Dept Sport Exercise & Hlth, Birsstr 320B, CH-4052 Basel, Switzerland.
    Borjesson, Mats
    Univ Gothenburg, Sahlgrenska Acad, Dept Physiol, Gothenburg; Ostra Hosp, Gothenburg; Univ Gothenburg, Dept Food & Nutr & Sport Sci, Gothenburg.
    Ljung, Thomas
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lindwall, Magnus
    Univ Gothenburg, Dept Food & Nutr & Sport Sci, Gothenburg; Univ Gothenburg, Dept Psychol, Gothenburg.
    Jonsdottir, Ingibjoerg H.
    Univ Gothenburg, Dept Food & Nutr & Sport Sci, Gothenburg; Inst Stress Med, Gothenburg.
    Fitness Moderates the Relationship between Stress and Cardiovascular Risk Factors2016In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, no 11, p. 2075-2081Article in journal (Refereed)
    Abstract [en]

    Purpose This cross-sectional observational study examined the degree to which cardiorespiratory fitness (CRF) and self-perceived stress are associated with cardiometabolic risk factors and the overall risk score for cardiovascular diseases. The second aim was to determine whether participants' CRF levels moderate the relationships between stress and cardiometabolic risk. Methods A gender-matched stratified sample (N = 197, 51% men, M-age = 39.2 yr) was used to ensure that participants with varying stress levels were equally represented. CRF was assessed with the angstrom strand bicycle test, and perceived stress was assessed with a single-item question. Systolic blood pressure (SBP) and diastolic blood pressure (DBP), body mass index (BMI), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), glycated hemoglobin, and total cardiometabolic risk score (sum of the z-standardized residuals of the previously mentioned indicators) were assessed as outcomes. Results Higher LDL-C, TG, and total metabolic risk were found in participants with high stress scores (P < 0.05). In addition, lower SBP, DBP, BMI, LDL-C, TG, and total metabolic risk were observed in participants with high CRF (P < 0.05). Two-way ANCOVA provided significant interaction effects for five of the nine outcome variables (P < 0.05, 3.6%-4.8% of explained variance). Participants with high stress who also had high CRF levels had lower SBP, DBP, LDL-C, TG, and total cardiometabolic risk than participants with high stress but low or moderate CRF levels. No significant main or interaction effects occurred for BMI, total cholesterol, high-density lipoprotein cholesterol, and glycated hemoglobin. Conclusion Better CRF is associated with more favorable levels of several cardiometabolic risk factors, specifically in participants experiencing high stress. Higher CRF may provide some protection against the health hazards of high chronic stress by attenuating the stress-related increase in cardiovascular risk factors.

  • 20.
    Hanstock, Helen
    et al.
    Bangor University, UK.
    Walsh, Neil P
    Bangor University, UK.
    Edwards, Jason P
    Bangor University, UK.
    Fortes, Matthew B
    Bangor University, UK.
    Cosby, Sarah L
    Queen’s University Belfast, Northern Ireland, UK.
    Nugent, Aaron
    Queen’s University Belfast, Northern Ireland, UK.
    Curran, Tanya
    Royal Victoria Hospital, Belfast, UK.
    Coyle, Peter V
    Royal Victoria Hospital, Belfast, UK.
    Ward, Mark D
    Bangor University, UK.
    Aw Yong, Xin Hui
    Bangor University, UK.
    Tear Fluid SIgA as a Noninvasive Biomarker of Mucosal Immunity and Common Cold Risk2016In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, no 3, p. 569-577Article in journal (Refereed)
    Abstract [en]

    Purpose: Research has not convincingly demonstrated the utility of saliva secretory Immunoglobulin-A (SIgA) as a biomarker of upper-respiratory-tract-infection (URTI) risk and disagreement exists about the influence of heavy exercise ('open-window-theory') and dehydration on saliva SIgA. Prompted by the search for viable alternatives, we compared the utility of tear and saliva SIgA to predict URTI prospectively (study-one) and assessed the influence of exercise (study-two) and dehydration (study-three) using a repeated-measures-crossover design.Methods: In study-one, forty subjects were recruited during the common-cold season. Subjects provided tear and saliva samples weekly and recorded upper-respiratory-symptoms (URS) daily for 3-weeks. RT-PCR confirmed common-cold pathogens in 9 of 11 subjects reporting URS (82%). Predictive utility of tear and saliva SIgA was explored by comparing healthy samples with those collected the week pre-URS. In study-two, thirteen subjects performed a 2-hour run at 65% VO2peak. In study-three, thirteen subjects performed exercise-heat-stress to 3% body-mass-loss followed by overnight fluid restriction.Results: Tear SIgA concentration and secretion rate were 48% and 51% lower respectively during URTI and 34% and 46% lower the week pre-URS (P<0.05) but saliva SIgA remained unchanged. URS risk the following week increased 9-fold (95% CI: 1.7 to 48) when tear SIgA secretion rate <5.5 μg[BULLET OPERATOR]min and 6-fold (95% CI: 1.2 to 29) when tear SIgA secretion rate decreased >30%. Tear SIgA secretion rate >5.5 μg[BULLET OPERATOR]min or no decrease >30% predicted subjects free of URS in >80% of cases. Tear SIgA concentration decreased post-exercise (-57%: P<0.05) in line with the 'open-window-theory' but was unaffected by dehydration. Saliva flow rate decreased and saliva SIgA concentration increased post-exercise and during dehydration (P<0.05).Conclusion: Tear SIgA has utility as a non-invasive biomarker of mucosal immunity and common-cold risk.

  • 21.
    Holmberg, Hans-Christer
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lindinger, Stefan
    University of Salzburg, Austria.
    Stöggl, Thomas
    University of Salzburg, Austria.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Muller, Erich
    University of Salzburg, Austria.
    Contribution of the legs to double-poling performance in elite cross country skiers2006In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 38, no 10, p. 1853-1860Article in journal (Refereed)
    Abstract [en]

    PURPOSE: In the classical style of cross-country skiing, the double-poling (DP) technique, which is regarded as an upper-body exercise, is used on the flatter parts of a course. Limited biomechanical and physiological data are available about DP compared with other cross-country skiing techniques. The purpose of the present study was to evaluate the possible role of the lower body during DP. METHODS: Eleven elite cross-country skiers performed two incremental tests using DP roller skiing at 1 degree inclination on a treadmill with or without locking the knee and ankle joints (DPLOCKED and DPFREE). Maximal and peak oxygen uptake (VO2max and VO2peak) during classic diagonal skiing and DP, respectively, were measured. In addition, heart rate, blood lactate concentration, and maximal DP velocity (Vmax) were determined. Pole-ground reaction forces and joint angles (elbow, hip, knee, and ankle) were analyzed. RESULTS: The skiers obtained 7.7% higher VO2peak, 9.4% higher Vmax, and 11.7% longer time to exhaustion during DPFREE compared with DPLOCKED (all P < 0.05). There was a higher heart rate and blood lactate concentration in DPLOCKED at submaximal stages (all P < 0.05), with no difference in oxygen consumption. At 85% Vmax, corresponding to approximately 81% VO2peak FREE, the differences in physiological variables were accompanied by a 13.6% higher poling frequency, a 4.9% shorter poling phase, 13.3% shorter recovery phase, and 10.9% lower relative pole force in DPLOCKED (all P < 0.05). CONCLUSIONS: Movements of the knee and ankle joints are an integrative part in the skillful use of the DP technique, and restriction of the motion in these joints markedly affects both biomechanical and physiological variables, impairing DP performance.

  • 22.
    Hébert-Losier, Kim
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Mourot, L.
    Univ Franche Comte, Res Unit Dept EA4660 Dept, Culture Sport Hlth Soc, F-25030 Besancon, France.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Elite and amateur orienteers' running biomechanics on three surfaces at three speeds2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 2, p. 381-389Article in journal (Refereed)
    Abstract [en]

    PURPOSE: Orienteering athletes must adapt to running on various surfaces, with biomechanics likely contributing to performance. Here, our aims were to identify the effect of athletic status and of surface on the running biomechanics of orienteers. METHODS: Seven elite and seven amateur male orienteers ran 20 m on road, path, and forest surfaces at maximal, 3.8 m·s, and 85% of maximal speeds. A three-dimensional motion capturing system monitored temporal gait and lower extremity kinematic parameters. Data were analyzed using mixed effects models that considered surface (road-path-forest), group (elite-amateur), and surface-group interaction effects. RESULTS: Forest running at maximal speed was slower and involved longer step and cycle times, greater knee extension at foot strike, smaller peak hip flexion and dorsiflexion during stance, and increased ranges of vertical pelvis motion compared with those observed on the road. Elites specifically exhibited greater hip extension at foot strike, larger dorsiflexion at toe-off, and lower pelvis at foot strike and toe-off, whereas amateurs displayed longer stance, greater plantarflexion at foot strike, and greater knee with lesser ankle motion. At the slowest speed, subjects exhibited greater knee flexion at foot strike, greater dorsiflexion at toe-off, shorter strides, smaller peak dorsiflexion during stance, and greater hip, knee, and vertical pelvis motions on forest than on road surfaces. Elites specifically demonstrated shorter stance, step, and cycle times whereas amateurs did not. CONCLUSIONS: Orienteering athletes adjusted their running biomechanics when off-road, with distinct adaptations observed in elite versus amateur competitors. The vertical pelvis motion was consistently greater when running off-road, coherent with reported increases in energy expenditure. However, our athletes did not exhibit more crouched lower limb postures when sprinting in the forest, indicating alternative responses to off-road running to that previously proposed by "Groucho" running.

  • 23.
    Hébert-Losier, Kim
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Platt, Simon
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Hopkins, William G.
    Victoria Univ, Coll Sport & Exercise Sci, Melbourne, Vic 8001, Australia.
    Sources of Variability in Performance Times at the World Orienteering Championships2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 7, p. 1523-1530Article in journal (Refereed)
    Abstract [en]

    Purpose An improvement equal to 0.3 of the typical variation in an elite athlete's race-to-race performance estimates the smallest worthwhile enhancement, which has not yet been determined for orienteers. Moreover, much of the research in high-performance orienteering has focused on physical and cognitive aspects, although course characteristics might influence race performance. Analysis of race data provides insights into environmental effects and other aspects of competitive performance. Our aim was to examine such factors in relation to World Orienteering Championships performances. Methods We used mixed linear modelling to analyze finishing times from the three qualification rounds and final round of the sprint, middle-distance, and long-distance disciplines of World Orienteering Championships from 2006 to 2013. Models accounted for race length, distance climbed, number of controls, home advantage, venue identity, round (qualification final), athlete identity, and athlete age. Results Within-athlete variability (coefficient of variation, mean SD) was lower in the final (4.9% +/- 1.4%) than in the qualification (7.3% +/- 2.4%) rounds and provided estimates of smallest worthwhile enhancements of 1.0%-3.5%. The home advantage was clear in most disciplines, with distance climbed particularly impacting sprint performances. Small to very large between-venue differences were apparent. Performance predictability expressed as intraclass correlation coefficients was extremely high within years and was high to very high between years. Age of peak performance ranged from 27 to 31 yr. Conclusions Our results suggest that elite orienteers should focus on training and strategies that enhance performance by at least 1.0%-3.5% for smallest worthwhile enhancement. Moreover, as greater familiarity with the terrain likely mediated the home advantage, foreign athletes would benefit from training in nations hosting the World Orienteering Championships for familiarization.

  • 24. Jacobs, I
    et al.
    Bar-Or, O
    Karlsson, J
    Dotan, R
    Tesch, P.A
    Kaiser, P
    Inbar, O
    Changes in muscle metabolites in females with 30-s exhaustive exercise1982In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 14, no 6, p. 457-460Article in journal (Refereed)
  • 25.
    Kent, Jane A.
    et al.
    Univ Massachusetts, Dept Kinesiol, Totman 160A, Amherst, MA 01003 USA.
    Örtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Univ Southern Denmark, Inst Sports Sci & Clin Biomech, Odense, Denmark.
    Hogan, Michael C.
    Univ Calif San Diego, Dept Med, San Diego, CA 92103 USA.
    Poole, David C.
    Kansas State Univ, Dept Kinesiol, Manhattan, KS 66506 USA.
    Musch, Timothy I.
    Kansas State Univ, Dept Kinesiol, Manhattan, KS 66506 USA.
    No Muscle Is an Island: Integrative Perspectives on Muscle Fatigue2016In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, no 11, p. 2281-2293Article in journal (Refereed)
    Abstract [en]

    Muscle fatigue has been studied with a variety approaches, tools and technologies. The foci of these studies have ranged tremendously, from molecules to the entire organism. Single cell and animal models have been used to gain mechanistic insight into the fatigue process. The theme of this review is the concept that the mechanisms of muscle fatigue do not occur in isolation in vivo: muscular work is supported by many complex physiological systems, any of which could fail during exercise and thus contribute to fatigue. To advance our overall understanding of fatigue, a combination of models and approaches is necessary. In this review, we examine the roles that neuromuscular properties, intracellular glycogen, oxygen metabolism, and blood flow play in the fatigue process during exercise and pathological conditions.

  • 26. Lindinger, Stefan
    et al.
    Stöggl, Thomas
    Müller, Erich
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Control of speed during the double poling technique performed by elite cross-country skiers2009In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 41, no 1, p. 210-220Article in journal (Refereed)
    Abstract [en]

    PURPOSE: Double poling (DP) as a main technique in cross-country skiing has developed substantially over the last 15 yr. The purpose of the present study was to analyze the question, "How do modern elite skiers control DP speed?" METHODS: Twelve male elite cross-country skiers roller skied using DP at 9, 15, 21, and 27 km.h(-1) and maximum velocity (V(max)). Cycle characteristics, pole and plantar forces, and elbow, hip, and knee joint angles were analyzed. RESULT: Both poling frequency and cycle length increased up to 27 km.h (-1)(P < 0.05), with a further increase in poling frequency at V(max) (P < 0.05). Peak pole force, rate of force development, and rearfoot plantar force increased with submaximal velocities (V(sm)), whereas poling time and time-to-peak pole force gradually shortened (P < 0.05). Changes in elbow joint kinematics during the poling phase were characterized by a decreased angle minimum and an increased flexion and extension ranges of motion as well as angular velocities across V(sm) (P < 0.05), with no further changes at V(max). Hip and knee joint kinematics adapted across V(sm) by 1) decreasing angles at pole plant and angle minima during the poling phase, 2) increasing the ranges of motion and angular velocities during the flexion phases occurring around pole plant, and 3) increasing extension ranges of motion and angular velocities during the recovery phase (all P values <0.05), with no further changes at V(max). CONCLUSIONS: Elite skiers control DP speed by increasing both poling frequency and cycle length; the latter is achieved by increased pole force despite reduced poling time. Adaptation to higher speeds was assisted by an increased range of motion, smaller angle minima, and higher angular velocities in the elbow, the hip, and the knee joints.

  • 27.
    Lundberg, Tommy
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Fernandez-Gonzalo, Rodrigo
    Karolinska Institutet.
    Åkerström, Sofie
    Tesch, Per
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Increase in Muscle Size Following 5-wk Resistance Training is Exaggerated by Concurrent Aerobic Exercise2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no Suppl 2 (5S), p. 88-88Article in journal (Refereed)
  • 28.
    Lundberg, Tommy R.
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Fernandez-Gonzalo, Rodrigo
    Institute of Biomedicine, University of León, León, Spain.
    Gustafsson, Thomas
    Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden.
    Tesch, Per A.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Aerobic Exercise Alters Skeletal Muscle Molecular Responses to Resistance Exercise2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no 9, p. 1680-1688Article in journal (Refereed)
    Abstract [en]

    LUNDBERG, T. R., R. FERNANDEZ-GONZALO, T. GUSTAFSSON, and P. A. TESCH. Aerobic Exercise Alters Skeletal Muscle Molecular Responses to Resistance Exercise. Med. Sci. Sports Exerc., Vol. 44, No. 9, pp. 1680-1688, 2012. Purpose: This study assessed the influence of an acute aerobic exercise bout on molecular responses to subsequent resistance exercise (RE). Methods: Nine physically active men performed a 45-min one-legged cycle ergometry exercise and 4 x 7 maximal concentric eccentric knee extensions for each leg 6 h later. Thus, one limb was subjected to aerobic and resistance exercise (AE+RE), and the contralateral limb to resistance exercise (RE) only. Knee extensor peak power was determined. Biopsies were obtained from the m vastus lateralis before (PRE) and 15 mm (POST1) and 3 h after RE. Analysis determined glycogen content, mRNA levels (vascular endothelial growth factor, peroxisome proliferator activated receptor-gamma coactivator-1, muscle RING-finger protein-1, atrogin-1, myostatin), and phosphorylated proteins (mammalian target of rapamycin, p70S6 kinase, ribosomal protein S6, eukaryotic elongation factor 2). Results: Peak power was similar in AE + RE and RE. After RE, the time course of glycogen utilization and protein signaling was similar across legs. However, phosphorylation of mammalian target of rapamycin and p70S6 kinase was elevated in AE + RE versus RE (main effect, P < 0.05). Vascular endothelial growth factor and peroxisome proliferator activated receptor-gamma coactivator-1 were higher in AE + RE than in RE at PRE and POST1 (P < 0.05). Myostatin was lower in AE + RE versus RE at PRE and POST1 (P < 0.05) and downregulated after resistance exercise only. Atrogin-1 was higher in AE + RE than in RE at PRE and POST1 (P < 0.05) and decreased after RE in AE + RE. Muscle RING-finger protein-1 was similar across legs. No difference for any marker was evident 3 h after RE. Conclusions: These results suggest that acute aerobic exercise alters molecular events regulating muscle protein turnover during the early recovery period from subsequent RE.

  • 29.
    Lundberg, Tommy R.
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Fernandez-Gonzalo, Rodrigo
    Karolinska Inst, Stockholm, Sweden.
    Rodriguez-Miguelez, Paula
    Univ Leon, E-24071 Leon, Spain.
    Tesch, Per A.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Karolinska Inst, Stockholm, Sweden.
    Relationship Between Acute Myostatin Expression, p70S6K Phosphorylation and Muscle Adaptations to Aerobic and Resistance Training2013In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 45, no 5, p. 528-528Article in journal (Other academic)
  • 30. Mekjavic, I.B
    et al.
    Exner, J.A
    Tesch, P.A
    Eiken, O
    Hyperbaric oxygen therapy does not affect recovery from delayed onset muscle soreness2000In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 32, no 3, p. 558-563Article in journal (Refereed)
  • 31.
    Radom-Aizik, Shlomit
    et al.
    Univ Calif Irvine, Irvine, CA USA .
    Haddad, Fadia
    Univ Calif Irvine, Irvine, CA USA .
    Owerkowicz, Tomasz
    Calif State Univ San Bernardino, San Bernardino, CA 92407 USA .
    Devaney, Joseph M.
    George Washington Univ, Children Natl Med Ctr, Washington, DC USA .
    Hoffman, Eric P.
    George Washington Univ, Children Natl Med Ctr, Washington, DC USA .
    Tesch, Per A.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Adams, Gregory R.
    Univ Calif Irvine, Irvine, CA USA .
    DNA Methylation is Altered in Human Skeletal Muscle in Response to Exercise Training2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no Suppl 2, p. 348-348Article in journal (Other academic)
  • 32.
    Sandbakk, Oyvind
    et al.
    Norwegian Univ Sci & Technol, Ctr Elite Sports Res, Dept Neurosci, N-7491 Trondheim, Norway.
    Hegge, Ann Magdalen
    Norwegian Univ Sci & Technol, Ctr Elite Sports Res, Dept Neurosci, N-7491 Trondheim, Norway.
    Losnegard, Thomas
    Norwegian Sch Sports Sci, Dept Phys Performance, Oslo, Norway.
    Skattebo, Oyvind
    Norwegian Sch Sports Sci, Dept Phys Performance, Oslo, Norway.
    Tonnessen, Espen
    Norwegian Olymp Federat, Oslo, Norway.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    The Physiological Capacity of the World's Highest Ranked Female Cross-country Skiers2016In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, no 6, p. 1091-1100Article in journal (Refereed)
    Abstract [en]

    Purpose The objective of this study is to compare the physiological capacity and training characteristics of the world's six highest ranked female cross-country skiers (world class (WC)) with those of six competitors of national class (NC). Methods Immediately before the start of the competition season, all skiers performed three 5-min submaximal stages of roller skiing on a treadmill for measurement of oxygen cost, as well as a 3-min self-paced performance test using both the double poling (DP) and diagonal stride (DIA) techniques. During the 3-min performance tests, the total distance covered, peak oxygen uptake (VO2peak), and accumulated oxygen deficit were determined. Each skier documented the intensity and mode of their training during the preceding 6 months in a diary. Results There were no differences between the groups with respect to oxygen cost or gross efficiency at the submaximal speeds. The WC skiers covered 6%-7% longer distances during the 3-min tests and exhibited average VO2peak values of approximate to 70 and approximate to 65 mLmin(-1)kg(-1) with DIA and DP, respectively, which were 10% and 7% higher than the NC skiers (all P < 0.05). However, the accumulated oxygen deficit did not differ between groups. From May to October, the WC skiers trained a total of 532 73 h (270 +/- 26 sessions) versus 411 +/- 62 h (240 +/- 27 sessions) for the NC skiers. In addition, the WC skiers performed 26% more low-intensity and almost twice as much moderate-intensity endurance and speed training (all P < 0.05). Conclusions This study highlights the importance of a high oxygen uptake and the ability to use this while performing the different skiing techniques on varying terrains for female cross-country skiers to win international races. In addition, the training data documented here provide benchmark values for female endurance athletes aiming for medals.

  • 33.
    Sarin, Heikki V.
    et al.
    National Institute for Health and Welfare, Helsinki, Finland; University of Helsinki, Helsinki, Finland.
    Ahtiainen, Juha P.
    University of Jyväskylä, Jyväskylä, Finland.
    Hulmi, Juha J.
    University of Jyväskylä, Jyväskylä, Finland; University of Helsinki, Helsinki, Finland.
    Ihalainen, Johanna K.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. University of Jyväskylä, Jyväskylä, Finland.
    Walker, Simon
    University of Jyväskylä, Jyväskylä, Finland.
    Küüsmaa-Schildt, Maria
    University of Jyväskylä, Jyväskylä, Finland.
    Perola, Markus
    National Institute for Health and Welfare, Helsinki, Finland; University of Helsinki, Helsinki, Finland.
    Peltonen, Heikki
    University of Jyväskylä, Jyväskylä, Finland.
    Resistance Training Induces Antiatherogenic Effects on Metabolomic Pathways2019In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 51, no 9, p. 1866-1875Article in journal (Refereed)
    Abstract [en]

    Introduction Arising evidence suggests that resistance training has the potential to induce beneficial modulation of biomarker profile. To date, however, only immediate responses to resistance training have been investigated using high-throughput metabolomics whereas the effects of chronic resistance training on biomarker profile have not been studied in detail. Methods A total of 86 recreationally active healthy men without previous systematic resistance training background were allocated into (i) a resistance training (RT) group (n = 68; age, 33 ± 7 yr; body mass index, 28 ± 3 kg·m-2) and (ii) a non-RT group (n = 18; age, 31 ± 4 yr; body mass index, 27 ± 3 kg·m-2). Blood samples were collected at baseline (PRE), after 4 wk (POST-4wk), and after 16 wk of resistance training intervention (POST-16wk), as well as baseline and after the non-RT period (20-24 wk). Nuclear magnetic resonance-metabolome platform was used to determine metabolomic responses to chronic resistance training. Results Overall, the resistance training intervention resulted in favorable alterations (P &lt; 0.05) in body composition with increased levels of lean mass (2.8%), decreased levels of android (9.6%), and total fat mass (7.5%). These changes in body composition were accompanied by antiatherogenic alterations in serum metabolome profile (false discovery rate &lt; 0.05) as reductions in non-high-density lipoprotein cholesterol (e.g., free cholesterol, remnant cholesterol, intermediate-density lipoprotein cholesterols, low-density lipoprotein cholesterols) and related apolipoprotein B, and increments in conjugated linoleic fatty acids levels were observed. Individuals with the poorest baseline status (i.e., body composition, metabolome profile) benefitted the most from the resistance training intervention. Conclusions In conclusion, resistance training improves cardiometabolic risk factors and serum metabolome even in previously healthy young men. Thus, suggesting attenuated risk for future cardiovascular disease. 

  • 34.
    Stoeggl, Thomas Leonhard
    et al.
    Salzburg Univ, Dept Sport Sci & Kinesiol, Salzburg, Austria.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Olymp Comm, Stockholm.
    Double-Poling Biomechanics of Elite Cross-country Skiers: Flat versus Uphill Terrain2016In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 48, no 8, p. 1580-1589Article in journal (Refereed)
    Abstract [en]

    Introduction: In light of the recent revolutionary change in the use of the doublepoling (DP) technique in cross-country skiing, our purpose was to compare the associated kinetics and kinematics on flat (DPflat) and uphill terrain (DPup), as well as to identify factors that determine performance. Methods: Thirteen elite male cross-country skiers completed two incremental speed tests (V-peak) involving roller skiing with the DP technique at moderate (13 and 24 km.h(-1)) and high speed (15 and 28.5 km.h(-1)) on a treadmill that was flat (1 degrees) or tilted uphill (7 degrees). Pole forces and three-dimensional whole-body kinematics were monitored simultaneously. Results: In comparison to DPflat, during DPup, swing times were much shorter (-48%) and peak pole forces greater (+13%) and generated later during the poling phase (+68%), with higher impulses for all force components (+87%-123%). Furthermore, pole forces were 18% more effectively oriented for propulsion. During DPup, the skiers demonstrated more flexed elbows, as well as shoulder angles that were less flexed in the forward direction and less abducted throughout the poling phase, together with more highly flexed knee and ankle joints, a more upright thorax, less flexed hips, and a shortened backward swing after pole off. With DPup, the skiers raised their center of mass 25% more, attaining maximal heel raise and maximal vertical position at a timepoint closer to pole plant compared with flat. On the uphill incline, the magnitude of V-peak was positively related to body mass, relative pole length (% body height), and magnitude of heel raise. Conclusions: The present findings provide novel insights into the coordination, kinetics and kinematics of elite skiers while DP on flat and uphill terrain.

  • 35.
    Stöggl, Thomas
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria .
    Bishop, Phillip
    Department of Exercise Science and Kinesiology, University of Alabama, Tuscaloosa, AL, United States .
    Höök, Martina
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Willis, Sarah
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Olympic Committee, Stockholm, Sweden .
    Effect of carrying a rifle on physiology and biomechanical responses in biathletes2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 3, p. 617-624Article in journal (Refereed)
    Abstract [en]

    Purpose: This study aimed to assess the effect of carrying a rifle on the physiological and biomechanical responses of well-trained biathletes. Methods: Ten elite biathletes (five men and five women) performed ski skating with (R) or without a rifle (NR) on a treadmill using the V2 (5- incline) and V1 techniques (8-) at 8 and 6 kmIhj1, respectively, as well as at racing intensity (approximately 95% of peak oxygen uptake (VO2peak), 10.7 T 0.8 and 7.7 T 0.9 kmIhj1, respectively). VO2, ventilation (VE), HR, blood lactate concentration (BLa), and cycle characteristics as well as pole and leg kinetics were evaluated during these trials. Results: Metabolic data were all higher for R than for NR, as follows:VO2, +2.5%;VE, +8.1%; RER, +4.2%; all P G 0.001; HR, +1.7%; and BLa, +15.1%; both P G 0.05. Biomechanically, carrying a rifle reduced cycle time and length, poling and arm swing times, and leg ground contact time and increased cycle rate, the peak and impulse of leg force, average cycle force, and impulse of forefoot force (all P G 0.05). With the exception of elevated pole forces when V2 skating at racing velocity, there were no differences between the peak and impulse of pole force. The difference inVE between R and NR was greater for the women than that for men (P G 0.05), and the difference in BLa also tended to be larger for the women (P G 0.1). Conclusions: Carrying a rifle elevated physiological responses, accelerated cycle rate, and involved greater leg work, with no differences between the V1 and V2 techniques.

  • 36.
    Stöggl, Thomas
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Salzburg Univ, Dept Sport Sci & Kinesiol, A-5020 Salzburg, Austria.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Olymp Comm, Stockholm, Sweden.
    Three-dimensional Force and Kinematic Interactions in V1 Skating at High Speeds2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 6, p. 1232-1242Article in journal (Refereed)
    Abstract [en]

    Purpose: To describe the detailed kinetics and kinematics associated with use of the V1 skating technique at high skiing speeds and to identify factors that predict performance. Methods: Fifteen elite male cross-country skiers performed an incremental roller-skiing speed test (V-peak) on a treadmill using the V1 skating technique. Pole and plantar forces and whole-body kinematics were monitored at four submaximal speeds. Results: The propulsive force of the "strong side'' pole was greater than that of the "weak side'' (P < 0.01), but no difference was observed for the legs. The poles generated approximately 44% of the total propulsion, being more effective than the legs in this respect (similar to 59% vs 11%, P < 0.001). Faster skiers exhibited more well-synchronized poling, exhibited more symmetric edging by and forces from the legs, and were more effective in transformation of resultant forces into propulsion. Cycle length was not correlated with either V-peak or the impulse of total propulsive forces. Conclusions: The present findings provide novel insights into the coordination, kinetics, and kinematics of the arm and leg motion by elite athletes while V1 skating at high speeds. The faster skiers exhibit more symmetric leg motion on the "strong'' and "weak'' sides, as well as more synchronized poling. With respect to methods, the pressure insoles and three-dimensional kinematics in combination with the leg push-off model described here can easily be applied to all skating techniques, aiding in the evaluation of skiing techniques and comparison of effectiveness.

  • 37.
    Stöggl, Thomas
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Department of Sport Science and Kinesiology, University of Salzburg, Schlossallee 49, 5400 Hallein/Rif, Salzburg, Austria.
    Hébert-Losier, Kim
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Olympic Committee, Stockholm, Sweden .
    Do Anthropometrics, Biomechanics, and Laterality Explain V1 Side Preference in Skiers?2013In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 45, no 8, p. 1569-1576Article in journal (Refereed)
    Abstract [en]

    PURPOSE: In cross-country (XC) skiing, the V1 and V2 alternate skate techniques are asymmetric, and skiers can choose either the right or left side for pole support. The overall purpose of this study was to investigate V1 side preference in elite XC skiers, notably by documenting V1 skate side preference, dominant and nondominant V1peak speeds, left- to right-side differences (ΔL-R) in laboratory-based measurements, and relationships between side preference data. METHODS: Sixteen male elite XC skiers completed one incremental speed test using V1 on their dominant side and another incremental speed test using V1 on their nondominant side while roller-skiing on a treadmill. During these tests, V1peak speed, pole forces, and plantar forces were measured. A whole-body dual-energy x-ray absortiometry (DXA) scan measured anthropometric parameters and questionnaires established side preference for V2 alternate, overall laterality in XC skiing, handedness, footedness, and injury prevalence. RESULTS: Left-to-right V1 side preference was equally distributed among skiers. V1peak speed was approximately 4.5% greater on the dominant versus nondominant sides. V1peak Δ L-R were positively related to Δ L-R in V1-dominant peak pole forces only. Questionnaire data indicated that more skiers preferred V2 alternate right, with moderate correlations between preferred V1 and V2 alternate sides. The expression of a dominant side in V1 and V2 alternate increased as skiing speed increased from moderate to 15-km endurance-race to sprint-race speeds. However, no relationships were established between V1 or V2 side preference and handedness, footedness, or number of one-sided injuries. CONCLUSIONS: ΔL-R in measurements provide limited explanations for V1 side preferences in elite XC skiers. In fact, no systematic relations exist between V1 side preferences and anthropometric, biomechanical, or questionnaire data. Copyright © 2013 by the American College of Sports Medicine.

  • 38. Tesch, P.A
    Aspects on muscle properties and use in competitive Alpine skiing1995In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 27, no 3, p. 310-314Article in journal (Refereed)
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