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  • 1. Alkner, B.A
    et al.
    Berg, H.E
    Kozlovskaya, I
    Sayenko, D
    Tesch, P.A
    Effects of strength training, using a gravity-independent exercise system, performed during 110 days of simulated space station confinement2003In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 90, no 1-2, p. 44-49Article in journal (Refereed)
  • 2.
    Andersson, Erik
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 3. Andersson, Johan P A
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Repeated apneas do not affect the hypercapnic ventilatory response in the short term2009In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, no 4, p. 569-74Article in journal (Refereed)
    Abstract [en]

    Long-term training of breath-hold diving reduces the hypercapnic ventilatory response (HCVR), an index of the CO(2) sensitivity. The aim of the present study was to elucidate whether also short-term apnea training (repeating apneas with short intervals) reduces the HCVR, thereby being one contributing factor explaining the progressively increasing breath-holding time (BHT) with repetition of apneas. Fourteen healthy volunteers performed a series of five maximal-duration apneas with face immersion and two measurements of the HCVR, using the Read rebreathing method. The BHT increased by 43% during the series of apneas (P < 0.001). However, the slope of the HCVR test was not affected by the series of apneas, being 2.52 (SD 1.27) and 2.24 (SD 1.14) l min(-1) mmHg(-1) in the control test and in the test performed within 2 min after the last apnea of the series, respectively (NS). Thus, a change in the HCVR cannot explain the observed short-term training effect on BHT.

  • 4. Beaven, Christopher
    Ultradian rhythmicity and induced changes in salivary testosterone2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 10, no 2, p. 405-413Article in journal (Refereed)
    Abstract [en]

    Testosterone and cortisol respond to exercise stimuli and modulate adaptation.Episodic basal secretion of these hormones may modify the responsiveness of these hormones.We sought to identify episodic steroid secretion via frequent salivary sampling and investigate any interaction between ultradian rhythmicity and induced changes in testosterone.

    Salivary testosterone and cortisol concentrations of seven males (age 20-40 y) were measured every 10 min between 0800-1600 h on three consecutive days.On either the second or third day, three interventions designed to elicit a hormonal response were randomly assigned: sprint exercise (two 30-s maximal efforts on a cycle ergometer); boxing (two 30-s maximal punching efforts); and a violent video game (10 min of player-versus-player combat).On the other days subjects were inactive.

    Testosterone data on non-intervention days suggested pulsatile secretion with a pulse interval of 47 ± 9 min (mean ± SD).The sprint intervention substantially affected hormones: it elicited a small transient elevation in testosterone (by a factor of 1.21; factor 90% confidence limits x/1.21) 10 min after exercise, and a moderate elevation in cortisol peaking 50 min post-exercise (factor 2.3; x/2.6).The testosterone response correlated with the change in testosterone concentration in the 10 min prior to the sprint (r=0.78; 90%CL 0.22 to 0.95) and with a measure of randomness in testosterone fluctuations (r=0.83; 0.35 to 0.96).

    Thus, the salivary testosterone response to exercise may be dependent on the underlying ultradian rhythm and aspects of its regulation.This interaction may have important implications for adaptation to exercise.

  • 5.
    Björklund, Glenn
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pettersson, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Performance predicting factors in prolonged exhausting exercise of varying intensity2007In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 99, no 4, p. 423-429Article in journal (Refereed)
    Abstract [en]

    Several endurance sports, e.g. road cycling, have a varying intensity profile during competition. At present, few laboratory tests take this intensity profile into consideration. Thus, the purpose of this study was to examine the prognostic value of heart rate (HR), lactate (La−1), potassium (K+), and respiratory exchange ratio (RER) performance at an exhausting cycling exercise with varying intensity. Eight national level cyclists performed two cycle tests each on a cycle ergometer: (1) a incremental test to establish VO2max, maximum power (W max), and lactate threshold (VO2LT), and (2) a variable intensity protocol (VIP). Exercise intensity for the VIP was based upon the VO2max obtained during the incremental test. The VIP consisted of six high intense (HI) workloads at 90% of VO2max for 3 min each, interspersed by five middle intense (MI) workloads at 70% of VO2max for 6 min each. VO2 and HR were continuously measured throughout the tests. Venous blood samples were taken before, during, and after the test. Increases in HR, La-, K+, and RER were observed when workload changed from MI to HI workload (P < 0.05). Potassium and RER decreased after transition from HI to MI workloads (P < 0.05). There was a negative correlation between time to exhaustion and decrease in La- concentration during the first MI (r = −0.714; P = 0.047). Furthermore, time to exhaustion correlated with VO2LT calculated from the ramp test (r = 0.738; P = 0.037). Our results suggest that the magnitude of decrease of La−1 between the first HI workload and the consecutive MI workload could predict performance during prolonged exercise with variable intensity

  • 6.
    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.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 7. Brink-Elfegoun, T.
    et al.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 8.
    Carlsson, Lars
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lind, Britta
    Royal Inst Technol KTH, Sch Technol & Hlth, Stockholm, Sweden .
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 9. Colliander, E.B
    et al.
    Dudley, G.A
    Tesch, P.A
    Skeletal muscle fiber type composition and performance during repeated bouts of maximal , concentric contractions1988In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 58, p. 81-86Article in journal (Refereed)
  • 10. Colliander, E.B
    et al.
    Tesch, P.A
    Bilateral eccentric and concentric torque at quadriceps and hamstrings muscles in females and males1989In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 59, no 3, p. 227-232Article in journal (Refereed)
  • 11.
    de Bruijn, Robert
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Richardson, Matthew
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Increased erythropoietin concentration after repeated apneas in humans2008In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 102, no 5, p. 609-613Article in journal (Refereed)
    Abstract [en]

    Hypoxia-induced increases in red blood cell production have been found in both altitudeadapted populations and acclimatized lowlanders. This process is mediated by erythropoietin (EPO) released mainly by the hypoxic kidney. We have previously observed high hemoglobin concentrations in elite breath-hold divers and our aim was to investigate whether apnea-induced hypoxia could increase EPO concentration. Ten healthy volunteers performed 15 voluntary maximal duration apneas, divided into three seriesof five apneas, each series separated by 10 min of rest. Apneas within series were separated by 2 min and preceded by 1 min of hyperventilation to increase apnea duration and arterial oxygen desaturation. When EPO concentration after serial apneas was compared to baseline values, an average maximum increase of 24% was found (P<0.01). No changes in EPO concentration were observed during a control day without apnea, eliminating possible effects of a diurnal rhythm or blood loss. We therefore conclude that serial apneas increase circulating EPO concentration in humans.

  • 12.
    Elmer, Steven J
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Amann, Marcus
    Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States.
    McDaniel, John
    Department of Exercise Science, Kent State University, Kent, OH, United States.
    Martin, David T.
    Department of Physiology, Australian Institute of Sport, Canberra, Australia.
    Martin, James C.
    Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, United States.
    Fatigue is specific to working muscles: no cross-over during single-leg cycling in trained cyclists2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 2, p. 479-488Article in journal (Refereed)
    Abstract [en]

    Fatigue induced via a maximal isometric contraction of a single limb muscle group can evoke a "cross-over" of fatigue that reduces voluntary muscle activation and maximum isometric force in the rested contralateral homologous muscle group. We asked whether a cross-over of fatigue also occurs when fatigue is induced via high-intensity endurance exercise involving a substantial muscle mass. Specifically, we used high-intensity single-leg cycling to induce fatigue and evaluated associated effects on maximum cycling power (P max) in the fatigued ipsilateral leg (FATleg) as well as the rested contralateral leg (RESTleg). On separate days, 12 trained cyclists performed right leg P max trials before and again 30 s, 3, 5, and 10 min after a cycling time trial (TT, 10 min) performed either with their right or left leg. Fatigue was estimated by comparing exercise-induced changes in P max and maximum handgrip isometric force (F max). Mean power produced during the right and left leg TTs did not differ (203 ± 8 vs. 199 ± 8 W). Compared to pre-TT, FATleg P max was reduced by 22 ± 3 % at 30 s post-TT and remained reduced by 9 ± 2 % at 5 min post-TT (both P < 0.05). Despite considerable power loss in the FATleg, post-TT RESTleg P max (596–603 W) did not differ from pre-TT values (596 ± 35 W). There were no alterations in handgrip F max (529–547 N). Our data suggest that any potential cross-over of fatigue, if present at all, was not sufficient to measurably compromise RESTleg P max in trained cyclists. These results along with the lack of changes in handgrip F max indicate that impairments in maximal voluntary neuromuscular function were specific to working muscles.

  • 13. Enocson, A. G
    et al.
    Berg, H. E.
    Vargas, A. R.
    Jenner, G
    Tesch, Per A
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Signal intensity of MR-images of thigh muscles following acute open- and closed chain kinetic knee extensor exercise – index of muscle use2005In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 94, no 4, p. 357-363Article in journal (Refereed)
    Abstract [en]

    Exercise-induced shifts in signal intensity (SI) of magnetic resonance (MR) images were examined to assess indirectly muscle use in closed- and open-chain knee extensor exercises. Eight men performed five sets of 8–12 repetitions in the leg press (LP) and the seated knee extension (KE) exercises at 50, 75 and 100%, respectively of the 5·10 repetition maximum (RM) load. Prior to exercise and after each load setting, images of the thigh were obtained. The increase in SI (D SI) of the quadriceps at 100% load was greater (P<0.05) after KE (32.1±9.0%) than after LP (21.9±9.2%). Regardless of load, the four individual muscles of the quadriceps showed similar changes in SI after LP. The three vastii muscles showed comparable increases in SI after KE. M. rectus femoris showed greater (P<0.05) D SI than the vastii muscles at 100%. Neither exercise produced increase in SI of mm. semimembranosus, semitendinosus, gracilis or biceps femoris. Mm. adductor magnus and longus showed increased (13.3±6.5%; P<0.05) SI after LP, but not after KE, at 100% load. The present data also infer greater involvement of the quadriceps muscle in the open-chain knee extension than in the closedchain leg press exercise. The results of the current investigation also indicate similar over-all use among the three vastii muscles in LP and KE, but ifferential m. rectus femoris use between the two exercises. This report extends the merits of the MR imaging technique as an aid to study individual muscle involvement in a particular exercise task.

  • 14. Essén-Gustavsson, B
    et al.
    Tesch, P.A
    Glycogen and triglyceride utilization in relation to muscle metabolic characteristics in men performing heavy resistance exercise1990In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 61, p. 5-10Article in journal (Refereed)
  • 15.
    Fernandez-Gonzalo, R.
    et al.
    Institute of Biomedicine (IBIOMED), University of León, León, Spain.
    Lundberg, Tommy R.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Alvarez-Alvarez, L.
    Institute of Biomedicine (IBIOMED), University of León, León, Spain.
    De Paz, J. A.
    Institute of Biomedicine (IBIOMED), University of León, León, Spain.
    Muscle damage responses and adaptations to eccentric-overload resistance exercise in men and women2014In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, no 5, p. 1075-1084Article in journal (Refereed)
    Abstract [en]

    Purpose: This study assessed markers of muscle damage and training adaptations to eccentric-overload flywheel resistance exercise (RE) in men and women. Methods: Dynamic strength (1 RM), jump performance, maximal power at different percentages of 1 RM, and muscle mass in three different portions of the thigh were assessed in 16 men and 16 women before and after 6 weeks (15 sessions) of flywheel supine squat RE training. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations were measured before, 24, 48 and 72 h after the first and the last training session. Results: After training, increases in 1 RM were somewhat greater (interaction P < 0.001) in men (25 %) than in women (20 %). Squat and drop jump height and power performance at 50, 60, 70 and 80 % of 1 RM increased after training in both sexes (P < 0.05). Power improvement at 80 % of 1 RM was greater (interaction P < 0.02) in men than women. Muscle mass increased ~5 % in both groups (P < 0.05). CK increased in men after the first training session (P < 0.001), whereas the response in women was unaltered. In both sexes, LDH concentration was greater after the first training session compared with basal values (P < 0.05). After the last session, CK and LDH remained at baseline in both groups. Conclusions: These results suggest that although improvements in maximal strength and power at high loads may be slightly greater for men, eccentric-overload RE training induces comparable and favorable gains in strength, power, and muscle mass in both men and women. Equally important, it appears muscle damage does not interfere with the adaptations triggered by this training paradigm. © 2014 Springer-Verlag Berlin Heidelberg.

  • 16.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 17. Jacobs, I
    et al.
    Kaiser, P
    Tesch, P.A
    Muscle strength and fatigue after selective glycogen depletion in human skeletal muscle fibers1981In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 46, no 1, p. 47-53Article in journal (Refereed)
  • 18. Komi, P.V
    et al.
    Tesch, P
    EMG frequency spectrum, muscle structure, and fatigue during dynamic contractions in man.1979In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 42, no 1, p. 41-50Article in journal (Refereed)
  • 19.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kemppainen, J.
    Turku PET Centre, University of Turku, Turku, Finland .
    Kyrolainen, H.
    Department of Biology of Physical Activity, Neuromuscular Research Centre, University of Jyväskylä, Jyväskylä, Finland .
    Knuuti, J.
    Turku PET Centre, University of Turku, Turku, Finland .
    Nuutila, P.
    Turku PET Centre, University of Turku, Turku, Finland .
    Kalliokoski, K. K.
    Turku PET Centre, University of Turku, Turku, Finland .
    Regional differences in blood flow, glucose uptake and fatty acid uptake within quadriceps femoris muscle during dynamic knee-extension exercise2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 7, p. 1775-1782Article in journal (Refereed)
    Abstract [en]

    The purpose of the present study was to investigate the regional differences in glucose and fatty acid uptake within skeletal muscle during exercise. Blood flow (BF), glucose uptake (GU) and free fatty acid uptake (FFAU) were measured in four different regions (vastus lateralis, VL; rectus femoris, RF; vastus intermedius, VI; and vastus medialis, VM) of the quadriceps femoris (QF) muscle during low-intensity, knee-extension exercise using positron emission tomography. BF was higher in VI than in VL, RF and VM (P < 0.05). FFAU was higher in VI (P < 0.001) but also in VM (P < 0.05) compared with VL and RF. In contrast, GU was higher in RF compared with VL (P < 0.05) but was not significantly different to VM or VI (both P = NS). FFAU within these four muscle regions correlated significantly with BF (r = 0.951, P < 0.05), whereas no significant relationship was observed between GU and BF (r = 0.352, P = NS). Therefore, skeletal muscle FFAU, but not GU, appears to be associated with BF during low-intensity exercise. The present results also indicate considerable regional differences in substrate use within working QF muscle. As such, an important methodological outcome from these results is that one sample from a specific part of the QF muscle does not represent the response in the entire QF muscle group.

  • 20. Larsson, L
    et al.
    Tesch, P.A
    Motor unit fibre density in extremely hypertrophied skeletal muscles in man1986In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 55, no 2, p. 130-136Article in journal (Refereed)
  • 21.
    Lindinger, Stefan
    et al.
    Salzburg Univ, Dept Sport Sci & Kinesiol, Christian Doppler Lab Biomech Skiing, A-5020 Salzburg, Austria .
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 22. Lindinger, Stefan J
    et al.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 23.
    Lund Ohlsson, Marie
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Sitting position affects performance in cross-country sit-skiing2017In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 117, no 6, p. 1095-1106Article in journal (Refereed)
    Abstract [en]

    Purpose: In cross-country sit-skiing (XCSS), athletes with reduced trunk control predominantly sit with the knees higher than the hips (KH); a position often associated with large spinal flexion. Therefore, to improve spinal curvature a new sledge with frontal trunk support, where knees are lower than hips (KL) was created. It was hypothesized that the KL position would improve respiratory function and enhance performance in seated double-poling compared to KH.

    Methods: Ten female able-bodied cross-country skiers (age 25.5 ± 3.8 years, height 1.65 ± 0.05 m, mass 61.1 ± 6.8 kg) completed a 30 s all-out test (WIN), a submaximal incremental test including 3–7 3 min loads (SUB) and a maximal 3 min time trial (MAX) in both KL and KH positions. During SUB and MAX external power, pole forces, surface electromyography, and kinematics were measured. Metabolic rates were calculated from oxygen consumption and blood lactate concentrations.

    Results: KL reduced spinal flexion and range of motion at the hip joint and indicated more muscle activation in the triceps. Performance (W kg−1) was impeded in both WIN (KH 1.40 ± 0.30 vs. KL 1.13 ± 0.33, p < 0.01) and MAX (KH 0.88 ± 0.19 vs. KL 0.67 ± 0.14, p < 0.01). KH resulted in higher gross efficiency (GE) and lower lactate concentration, anaerobic metabolic rate, and minute ventilation for equal power output.

    Conclusions: The new KL position can be recommended due to improved respiratory function but may impede performance. Generalization of results to XCSS athletes with reduced trunk muscle control may be limited, but these results can serve as a control for future studies of para-athletes.

  • 24. McGawley, Kerry
    et al.
    Bishop, David
    Reliability of a 5 x 6-s maximal cycling repeated-sprint test in trained female team-sport athletes2006In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 98, no 4, p. 383-393Article in journal (Refereed)
    Abstract [en]

    The present study examined the reliability of work and power measures during a 5 × 6-s cycle ergometer test of repeated-sprint ability. Nine, well-trained, female soccer players performed five, 5 × 6-s repeated-sprint tests on a front-access cycle ergometer on separate days. Sprints were separated by 24 s of active recovery. Absolute measures of total work done (W tot), total peak power (PPtot), work done during sprint 1 (W 1) and peak power output during sprint 1 (PP1) were recorded. Decrement scores in work done (W dec) and peak power output (PPdec), and fatigue indices for work done (FI W ) and peak power (FI P ), were calculated. Significant improvements in all of the work and power measures were observed between trial 1 and subsequent trials (P < 0.05), but no significant differences were identified between trials 2, 3, 4 and 5. The same was true for increases in the decrement scores. The coefficient of variation (CV) was established to reflect within-subject reproducibility for each variable. The CV was significantly improved by the third trial for work done (W tot CV: trials 1–2 = 5.5%; trials 3–4 = 2.8%), peak power (PPtot CV: trials 1–2 = 5.1%; trials 3–4 = 2.7%) and performance decrement scores (P < 0.05). The standard error of measurement (SEM) and intraclass correlation coefficient (ICC) were also calculated for each variable and expressed within 95% confidence intervals. It was concluded that two familiarisation trials are optimal for collecting reliable data from a 5 × 6-s repeated-sprint cycling test. Furthermore, due to the large variation around performance decrement it was suggested that decrement scores ought to be interpreted with caution.

  • 25.
    Nielsen, Joachim
    et al.
    Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, 5230 Odense M, Denmark.
    Krustrup, Peter
    Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark.
    Nybo, Lars
    Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark.
    Gunnarsson, Thomas P.
    Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark.
    Madsen, Klavs
    Department of Sport Science, Aarhus University, Aarhus, Denmark.
    Schröder, Henrik
    Institute of Pathology, University of Southern Denmark, Odense M, Denmark.
    Bangsbo, Jens
    Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark.
    Örtenblad, Niels
    Univ So Denmark, Inst Sports Sci & Clin Biomech, DK-5230 Odense M, Denmark.
    Skeletal muscle glycogen content and particle size of distinct subcellular localizations in the recovery period after a high-level soccer match2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 10, p. 3559-3567Article in journal (Refereed)
    Abstract [en]

    Whole muscle glycogen levels remain low for a prolonged period following a soccer match. The present study was conducted to investigate how this relates to glycogen content and particle size in distinct subcellular localizations. Seven high-level male soccer players had a vastus lateralis muscle biopsy collected immediately after and 24, 48, 72 and 120 h after a competitive soccer match. Transmission electron microscopy was used to estimate the subcellular distribution of glycogen and individual particle size. During the first day of recovery, glycogen content increased by ~60% in all subcellular localizations, but during the subsequent second day of recovery glycogen content located within the myofibrils (Intramyofibrillar glycogen, a minor deposition constituting 10–15% of total glycogen) did not increase further compared with an increase in subsarcolemmal glycogen (−7 vs. +25%, respectively, P = 0.047). Conversely, from the second to the fifth day of recovery, glycogen content increased (53%) within the myofibrils compared to no change in subsarcolemmal or intermyofibrillar glycogen (P < 0.005). Independent of location, increment in particle size preceded increment in number of particles. Intriguingly, average particle size decreased; however, in the period from 3 to 5 days after the match. These findings suggest that glycogen storage in skeletal muscle is influenced by subcellular localization-specific mechanisms, which account for an increase in number of glycogen particles located within the myofibrils in the period from 2 to 5 days after the soccer match.

  • 26. Norrbrand, Lena
    et al.
    Fluckey, J. D.
    Pozzo, M.
    Tesch, Per
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Resistance training using eccentric overload induces early adaptations in skeletal muscle size2008In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 102, no 3, p. 271-281Article in journal (Refereed)
    Abstract [en]

    Fifteen healthy men performed a 5-week training program comprising four sets of seven unilateral, coupled concentric-eccentric knee extensions 2-3 times weekly. While eight men were assigned to training using a weight stack (WS) machine, seven men trained using a flywheel (FW) device, which inherently provides variable resistance and allows for eccentric overload. The design of these apparatuses ensured similar knee extensor muscle use and range of motion. Before and after training, maximal isometric force (MVC) was measured in tasks non-specific to the training modes. Volume of all individual quadriceps muscles was determined by magnetic resonance imaging. Performance across the 12 exercise sessions was measured using the inherent features of the devices. Whereas MVC increased (P < 0.05) at all angles measured in FW, such a change was less consistent in WS. There was a marked increase (P < 0.05) in task-specific performance (i.e., load lifted) in WS. Average work showed a non-significant 8.7% increase in FW. Quadriceps muscle volume increased (P < 0.025) in both groups after training. Although the more than twofold greater hypertrophy evident in FW (6.2%) was not statistically greater than that shown in WS (3.0%), all four individual quadriceps muscles of FW showed increased (P < 0.025) volume whereas in WS only m. rectus femoris was increased (P < 0.025). Collectively the results of this study suggest more robust muscular adaptations following flywheel than weight stack resistance exercise supporting the idea that eccentric overload offers a potent stimuli essential to optimize the benefits of resistance exercise.

  • 27.
    Norrbrand, Lena
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pozzo, Marco
    Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, 171 77, Sweden.
    Tesch, Per
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Flywheel resistance training calls for greater eccentric muscle activation than weight training2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 110, no 5, p. 997-1005Article in journal (Refereed)
    Abstract [en]

    Changes in muscle activation and performance were studied in healthy men in response to 5 weeks of resistance training with or without “eccentric overload”. Subjects, assigned to either weight stack (grp WS; n = 8) or iso-inertial “eccentric overload” flywheel (grp FW; n = 9) knee extensor resistance training, completed 12 sessions of four sets of seven concentric–eccentric actions. Pre- and post-measurements comprised maximal voluntary contraction (MVC), rate of force development (RFD) and training mode-specific force. Root mean square electromyographic (EMGRMS) activity of mm. vastus lateralis and medialis was assessed during MVC and used to normalize EMGRMS for training mode-specific concentric (EMGCON) and eccentric (EMGECC) actions at 90°, 120° and 150° knee joint angles. Grp FW showed greater (p < 0.05) overall normalized angle-specific EMGECC of vastii muscles compared with grp WS. Grp FW showed near maximal normalized EMGCON both pre- and post-training. EMGCON for Grp WS was near maximal only post-training. While RFD was unchanged following training (p > 0.05), MVC and training-specific strength increased (p < 0.05) in both groups. We believe the higher EMGECC activity noted with FW exercise compared to standard weight lifting could be attributed to its unique iso-inertial loading features. Hence, the resulting greater mechanical stress may explain the robust muscle hypertrophy reported earlier in response to flywheel resistance training.

  • 28.
    Richardson, Matt
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    de Bruijn, Robert
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Hypoxia augments apnea-induced increase in hematocrit and hemoglobin concentration2009In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, no 1, p. 63-68Article in journal (Refereed)
    Abstract [en]

    Increased hemoglobin concentration (Hb) and hematocrit (Hct) attributable to spleen contraction raises blood gas storage capacity during apnea, but the mechanisms that trigger this response have not been clarified. We focused on the role of hypoxia in triggering these Hb and Hct elevations. After horizontal rest for 20 min, 10 volunteers performed 3 maximal apneas spaced by 2 min, each preceded by a deep inspiration of air. The series was repeated using the same apneic durations but after 1 min of 100% oxygen breathing and oxygen inspiration prior to apneas. Mean apneic durations were 150s, 171s, and 214s for apneas 1, 2, and 3, respectively. Relative to pre-apnea values, the mean post-apneic arterial oxygen saturation nadir was 84.7% after air and 98% after oxygen. A more pronounced elevation of both Hb and Hct occurred during the air trial: after apnea 1 with air, mean Hb had increased by 1.5% (P<0.01), but no clear increase was found after the first apnea in with oxygen. After the third apnea with air Hb had increased by 3.0% (P<0.01), and with oxygen by 2.0% (P<0.01). After the first apnea with air Hct had increased by 1.9% (P<0.01) and after 3 apneas by 3.0% (P<0.01), but Hct did not change significantly in the oxygen trial. In both trials, Hb and Hct were at pre-apneic levels 10 min after apneas. Diving bradycardia during apnea was the same in both trials. We concluded that hypoxia is essential in inducing spleen-related Hb and Hct increase during apnea.

  • 29.
    Richardson, Matt
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Lodin, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Reimers, J
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Short-term effects of normobaric hypoxia on the human spleen2008In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 104, no 2, p. 395-399Article in journal (Refereed)
    Abstract [en]

    Spleen contraction resulting in an increase in circulating erythrocytes has been shown to occur during apnea. This effect, however, has not previously been studied during normobaric hypoxia whilst breathing. After 20 min of horizontal rest and normoxic breathing, five subjects underwent 20-min of normobaric hypoxic breathing (12.8% oxygen) followed by 10 min of normoxic breathing. Ultrasound measurements of spleen volume and samples for venous hemoglobin concentration (Hb) and hematocrit (Hct) were taken simultaneously at short intervals from 20 min before until 10 min after the hypoxic period. Heart rate, arterial oxygen saturation (SaO2) and respiration rate were recorded continuously. During hypoxia, a reduction in SaO2 by 34% (P < 0.01) was accompanied by an 18% reduction in spleen volume and a 2.1% increase in both Hb and Hct (P < 0.05). Heart rate increased 28% above baseline (P < 0.05). Within 3 min after hypoxia SaO2 had returned to pre-hypoxic levels, and spleen volume, Hb and Hct had all returned to pre-hypoxic levels within 10 min. Respiratory rate remained stable throughout the protocol. This study of short-term exposure to eupneic normobaric hypoxia suggests that hypoxia plays a key role in triggering spleen contraction and subsequent release of stored erythrocytes in humans. This response could be beneficial during early altitude acclimatization.

  • 30. Rosdahl, Hans
    et al.
    Gullstrand, Lennart
    Salier-Eriksson, Jane
    Johansson, Patrik
    Schantz, Peter
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Evaluation of the Oxycon Mobile metabolic system against the Douglas bag method2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 109, no 2, p. 159-171Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate two versions of the Oxycon Mobile portable metabolic system, (OMPS1 and OMPS2) in a wide range of oxygen uptake, using the Douglas bag method (DBM) as criterion method. The metabolic variables VO2, VCO2, respiratory exchange ratio and VE were measured during submaximal and maximal cycle ergometer exercise with sedentary, moderately trained individuals and athletes as participants. Test-retest reliability was investigated using the OMPS1. The coefficients of variation varied between 2% and 7% for the metabolic parameters measured at different work rates, and resembled those obtained with the DBM. With the OMPS1, systematic errors were found in the determination of VO2 and VCO2. At submaximal work rates VO2 was 6-14% and VCO2 5-9% higher than with the DBM. At VO2max both VO2 and VCO2 were slightly lower as compared to DBM (-4.1% and -2.8% respectively). With OMPS2, VO2 was determined accurately within a wide measurement range (about 1-5.5 L*min-1), while VCO2 was overestimated (3-7%). VE was accurate at submaximal work rates with both OMPS1 and OMPS2, whereas underestimations (4-8%) were noted at VO2max. The present study is the first to demonstrate that a wide range of VO2 can be measured accurately with the Oxycon Mobile portable metabolic system (second generation). Future investigations are suggested to clarify reasons for the small errors noted for VE and VCO2 versus the Douglas bag measurements, and also to gain knowledge of the performance of the device under applied and non-laboratory conditions.

  • 31.
    Salier Eriksson, Jane
    et al.
    Swedish Sch Sport & Hlth, Lab Appl Sport Sci, GIH, Stockholm, Sweden .
    Rosdahl, Hans
    Swedish Sch Sport & Hlth, Lab Appl Sport Sci, GIH, Stockholm, Sweden .
    Schantz, Peter
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Validity of the Oxycon Mobile metabolic system under field measuring conditions2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 1, p. 345-355Article in journal (Refereed)
    Abstract [en]

    Purpose: It is essential to validate portable metabolic systems, not only in laboratory settings, but also in field measuring conditions, such as prolonged moderate exercise at low temperatures, high humidity and with external wind.

     

    Methods: VO2, VCO2, RER and VE were measured using the Oxycon Mobile (OM), with a windshield, during cycle ergometer exercise: (I) indoors at three submaximal workloads with no wind or with external wind (13–20 m·s-1) from front, side and back; (II) at two submaximal workloads outdoors (12 ± 2oC; 86 ± 7% RH), with and without a system for drying the ambient air around the air sampling tube; and (III) at one workload outdoors for 45 min (5 ± 4oC; 69 ± 16.5% RH). Any physiological drift was checked for with pre- and postmeasurements by the Douglas bag method (DBM).

     

    Results: A minor effect of external wind from behind was noted in RER and VE (-2 and -3%).. The system for drying the ambient air around the gas sampling tube had no effect on the measured levels. A small difference in VCO2 drift between the OM and DBM (1.5 mL·min-2) was noted in the stability test.

     

    Conclusion: Heavy external wind applied from different directions generally does not affect the measurements of the OM. Furthermore, when using a unit for drying the ambient air around the gas sampling tube, the OM can accurately measure VO2, RER and VE   at submaximal workloads for at least45 min under challenging conditions with regard to humidity and temperature.

  • 32.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 33.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 34.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 35.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 36.
    Sandbakk, Øyvind
    et al.
    Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 37.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andersson, Johan
    Nielsen, Bodil
    Hematological response and diving response during apnea and apnea with face immersion2007In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 101, no 1, p. 125-132Article in journal (Refereed)
    Abstract [en]

    Increased hematocrit (Hct) attributable to splenic contraction accompanies human apneic diving or apnea with face immersion. Apnea also causes heart rate reduction and peripheral vasoconstriction, i.e., a cardiovascular diving response, which is augmented by face immersion. The aim was to study the role of apnea and facial immersion in the initiation of the hematological response and to relate this to the cardiovascular diving response and its oxygen conservation during repeated apneas. Seven male volunteers performed two series of five apneas of fixed near-maximal duration: one series in air (A) and the other with facial immersion in 10°C water (FIA). Apneas were spaced by 2 min and series by 20 min of rest. Venous blood samples, taken before and after each apnea, were analysed for Hct, hemoglobin concentration (Hb), lactic acid, blood gases and pH. Heart rate, skin capillary blood flow and arterial oxygen saturation were continuously measured non-invasively. A transient increase of Hct and Hb by approximately 4% developed progressively across both series. As no increase of the response resulted with face immersion, we concluded that the apnea, or its consequences, is the major stimulus evoking splenic contraction. An augmented cardiovascular diving response occurred during FIA compared to A. Arterial oxygen saturation remained higher, venous oxygen stores were more depleted and lactic acid accumulation was higher across the FIA series, indicating oxygen conservation with the more powerful diving response. This study shows that the hematological response is not involved in causing the difference in oxygen saturation between apnea and apnea with face immersion

  • 38.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Haughey, Helena
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Reimers, J
    Speed of spleen volume changes evoked by serial apneas2005In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 93, no 4, p. 447-452Article in journal (Refereed)
    Abstract [en]

    Diving mammals may enhance dive duration by injecting extra erythrocytes into the circulation by spleen contraction. This mechanism may also be important for apneic duration in humans. We studied the speed and magnitude of spleen volume changes evoked by serial apneas, and the associated changes in hematocrit (Hct) and hemoglobin (Hb) concentration, diving response and apneic duration. Three maximal apneas separated by 2 min rest elicited spleen contraction in all ten subjects, by a mean of 49 (27) ml (18%; P<0.001). During the same period, Hct and Hb rose by 2.2 and 2.4% respectively (P<0.01 and P<0.001), and apneic duration rose by 20 s (22% P<0.05). The mean heart rate reduction of the diving response was 15%, which remained the same throughout the apnea series. While the diving response was completely reversed between the apneas, spleen size was not recovered until 8–9 min after the final apnea corresponding with recovery of Hct and Hb. Thus, although the spleen contraction may be associated with the cardiovascular diving response, it is likely to be triggered by different mechanisms, and it may remain activated between dives spaced by short pauses. The two adjustments may provide a fast, quickly reversed, and a slow, but long-lasting, way of shifting to a diving mode in humans

  • 39.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Kampen, Marja
    Emanuelsson, Stefan
    Holm, Boris
    Effects of physical and apnea training on apneic time and diving response in humans.2000In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 82, no 3, p. 161-169Article in journal (Refereed)
    Abstract [en]

    The aim of this investigation was to study separately the effects of physical training and apnea training on the diving response and apneic time in humans. Both types of training have been suggested to lead to prolonged apneic time and an increased “diving response” (i.e., regional vasoconstriction and bradycardia). The study was also designed to examine the effects of these two types of training on the characteristics of the increase in apneic time with repeated apneas. Simulated diving tests were performed before and after the different training programs. The test format was one apnea and five apneas with facial immersion in cold water at 2-min intervals. An increase in apneic time was observed after physical training (n=24), and this was attributable to an increased time beyond the physiological breaking point. The other parameters that were measured remained unaffected. After apnea training (n=9), however, apneic time was increased by a delay in the physiological breaking point, which is mainly determined by the arterial tension of CO2. The diving response had increased, and the effect of repeated apneas on apneic time tended to be larger after apnea training. These results may explain the pronounced diving responses and long apneas observed in trained apneic divers

  • 40.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 41.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 42.
    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
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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).

  • 43.
    Sperlich, Billy
    et al.
    Bergische Universität Wuppertal.
    Zinner, Christoph
    German Sport University Cologne.
    Hébert-Losier, Kim
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Born, Dennis-Peter
    Bergische Universität Wuppertal.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 44.
    Sperlich, Billy
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Univ Wurzburg, Dept Sport Sci, D-97082 Wurzburg, Germany.
    Zinner, Christoph
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pfister, Roman
    Univ Cologne, Dept Internal Med 3, D-50937 Cologne, Germany.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    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.

  • 45. Tesch, P.A
    et al.
    Karlsson, J
    Muscle metabolite accumulation following maximal exercise: a comparison between short-term and endurance kayak performance1984In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 52, no 2, p. 243-246Article in journal (Refereed)
  • 46. Tesch, P.A
    et al.
    Larsson, L
    Muscle hypertrophy in bodybuilders1982In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 49, no 3, p. 301-306Article in journal (Refereed)
  • 47. Tesch, P.A
    et al.
    Lindeberg, S
    Blood lactate accumulation during arm exercise in world class kayak paddlers and strength trained athletes1984In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 52, no 4, p. 441-445Article in journal (Refereed)
  • 48. Tesch, P.A
    et al.
    Wright, J.E
    Recovery from short-term intense exercise: its relation to capillary supply and blood lactate concentration1983In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 52, no 1, p. 98-103Article in journal (Refereed)
  • 49. Tesch, P.A
    et al.
    Wright, J.E
    Vogel, W.L
    Daniels, D.S
    Sharp, D.S
    Sjödin, B
    The influence of muscle metabolic characteristics on physical performance1985In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 54, no 3, p. 237-243Article in journal (Refereed)
  • 50.
    Tesch, Per A
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Berg, Hans E
    Bring, Daniel
    Evans, Halan J.
    LeBlanc, Adrian D
    Effects of 17-day spaceflight on knee extensor muscle function and size.: European journal of applied physiology2005In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 93, no 4, p. 463-468Article in journal (Refereed)
    Abstract [en]

    It is generally held that space travelers experience muscle dysfunction and atrophy during exposure to microgravity. However, observations are scarce and reports somewhat inconsistent with regard to the time course, specificity and magnitude of such changes. Hence, we examined four male astronauts (group mean 43 years, 86 kg and 183 cm) before and after a 17-day spaceflight (Space Transport System-78). Knee extensor muscle function was measured during maximal bilateral voluntary isometric and iso-inertial concentric, and eccentric actions. Cross-sectional area (CSA) of the knee extensor and flexor, and gluteal muscle groups was assessed by means of magnetic resonance imaging. The decrease in strength (P<0.05) across different muscle actions after spaceflight amounted to 10%. Eight ambulatory men, examined on two occasions 20 days apart, showed unchanged (P>0.05) muscle strength. CSA of the knee extensor and gluteal muscles, each decreased (P<0.05) by 8%. Knee flexor muscle CSA showed no significant (P>0.05) change. The magnitude of these changes concord with earlier results from ground-based studies of similar duration. The results of this study, however, do contrast with the findings of no decrease in maximal voluntary ankle plantar flexor force previously reported in the same crew.

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