Fatigue Induced by a Cross-Country Skiing KO Sprint

European Journal of Applied Physiology, 2008

The purpose of this study was (1) to determine the relationship between each individual's anaerobic power reserve (APR) [i.e., the difference between the maximum anaerobic (P ana ) and aerobic power (P aer )] and fatigability during repeated-sprint exercise and (2) to examine the acute effects of repeated sprints on neuromuscular activity, as evidenced by changes in the surface electromyogram (EMG) signals. Eight healthy males carried out tests to determine P ana (defined as the highest power output attained during a 6-s cycling sprint), P aer (defined as the highest power output achieved during a progressive, discontinuous cycling test to failure) and a repeated cycling sprint test (10 9 6-s max sprints with 30 s rest). Peak power output (PPO) and mean power output (MPO) were calculated for each maximal 6-s cycling bout. Root mean square (RMS) was utilized to quantify EMG activity from the vastus lateralis (VL) muscle of the right leg. Over the ten sprints, PPO and MPO decreased by 24.6 and 28.3% from the maximal value (i.e., sprint 1), respectively.

Kinesiology

This study investigated the etiology of neuromuscular fatigue induced by a 5-m shuttle run test (5MSRT) in soccer players. Nineteen adult male amateur soccer players (age: 20.0 ± 2.9 years) participated in the present study. Before and after the 5MSRT, they were instructed to complete a maximal voluntary isometric contraction (MVIC) of the knee extensors (KE) during and after which two electrical stimulations were applied at the femoral nerve. Voluntary activation level (VAL), surface electromyography recordings (sEMG), electrophysiological (Mmax) and potentiated resting twitch (Ptw) responses of the KE were compared between pre- and post-5MSRT. Rating of perception exertion (RPE) was also assessed before, during the test immediately following each sprint repetition and after the test. The distance covered during each sprint significantly decreased as the number of trials performed increased (p<.05). The RPE reported following each sprint significantly increased throughout the te...

Human movement science, 2015

Here, we tested the hypothesis that aerobic energy expenditure (AEE) is higher during a simulated 6-km (2 loops of 3-km each) "skiathlon" than during skating only on a treadmill and attempted to link any such increase to biomechanical and neuromuscular responses. Six elite male cross-country skiers performed two pre-testing time-trials (TT) to determine their best performances and to choose an appropriate submaximal speed for collection of physiological, biomechanical and neuromuscular data during two experimental sessions (exp). Each skier used, in randomized order, either the classical (CL) or skating technique (SK) for the first 3-km loop, followed by transition to the skating technique for the second 3-km loop. Respiratory parameters were recorded continuously. The EMG activity of the triceps brachii (TBr) and vastus lateralis (VLa) muscles during isometric contractions performed when the skiers were stationary (i.e., just before the first loop, during the transition, ...

Journal of Strength and Conditioning Research, 2017

The aim of this study was to assess different physiological variables before and after a 5-km (women) and 10-km (men) crosscountry skiing competition to determine potential mechanisms of fatigue. Fourteen elite-level skiers competed in an official crosscountry skiing competition using the classical style (9 men and 5 women). Instantaneous skiing velocity was measured during the race by means of 15-Hz global positioning system devices. Before and after the race, a sample of venous blood was obtained to assess changes in blood lactate and serum electrolyte and myoglobin concentrations. Prerace to postrace changes in blood oxygen saturation, forced vital capacity during a spirometry test, jump height during a countermovement jump, and handgrip force were also measured. Mean race speed was 15.8 6 2.5 and 15.4 6 1.5 km$h 21 , whereas mean heart rate was 171 6 6 and 177 6 3 b$min 21 for men and women, respectively. There were no significant prerace to postrace changes in jump height, handgrip force, and forced vital capacity in men and women. Blood oxygen saturation was reduced from prerace to postrace in men (95.9 6 2.1% to 93.1 6 2.3%, p = 0.02) and women (97.8 6 1.1% to 92.4 6 2.1%, p , 0.01), whereas blood lactate concentration increased at the end of the race in men (1.4 6 0.5 to 4.9 6 2.1 mmol$L 21 , p , 0.01) and women (1.9 6 0.1 to 6.9 6 3.2 mmol$L 21 , p , 0.01). After the race, blood markers of muscle damage were at low concentrations, whereas serum electrolytes remained unchanged. Fatigue in 5and 10-km crosscountry skiing competitions was related to a reduced blood oxygen carrying capacity and presumably increased muscle and blood acidosis, whereas the influence of exercise-induced muscle damage on fatigue was minor.

Distance running performance is dependent on the integration of the complex mechanisms of neuromuscular control, central and peripheral cardiovascular performance, and fatigue resistance. The end result of these interactions is movement, as defined by running mechanics. During high-intensity running, specific muscles may demonstrate signs of neuromuscular fatigue, which may alter running local and wholebody running mechanics. There are few published studies specific to running which describe neuromuscular fatigue of torso and arm muscles, how fatigue affects the kinematics of the upper body, and how neuromuscular fatigue relates to kinematic changes.

Scandinavian Journal of Medicine & Science in Sports, 2007

Nine experienced endurance runners performed individual marathon runs that involved several tests of neuromuscular performance before, during and after the marathon. The tests were performed with special force platform and dynamometer techniques. The results showed an overall decrease in performance from the marathon. The maximal sprint velocity decreased parabolically during the marathon, reaching the final value of 84% of the pre-marathon one. Similarly, the other test results after marathon indicated that maximal isometric knee extension torque was 78%, the performance in a special rebound test (drop jump) 84% and the 5-jump performance 92% of the pre-marathon values. These reductions were accompanied by alteration in the ground reaction force curves in the sprint and jump tests, suggesting reduced tolerance to stretch load as well as loss in the recoil characteristics of the muscles.

Journal of Applied Physiology, 2010

Millet GY. Central and peripheral contributions to neuromuscular fatigue induced by a 24-h treadmill run. This experiment investigated the fatigue induced by a 24-h running exercise (24TR) and particularly aimed at testing the hypothesis that the central component would be the main mechanism responsible for neuromuscular fatigue. Neuromuscular function evaluation was performed before, every 4 h during, and at the end of the 24TR on 12 experienced ultramarathon runners. It consisted of a determination of the maximal voluntary contractions (MVC) of the knee extensors (KE) and plantar flexors (PF), the maximal voluntary activation (%VA) of the KE and PF, and the maximal compound muscle action potential amplitude (Mmax) on the soleus and vastus lateralis. Tetanic stimulations also were delivered to evaluate the presence of low-frequency fatigue and the KE maximal muscle force production ability. Strength loss occurred throughout the exercise, with large changes observed after 24TR in MVC for both the KE and PF muscles (Ϫ40.9 Ϯ 17.0 and Ϫ30.3 Ϯ 12.5%, respectively; P Ͻ 0.001) together with marked reductions of %VA (Ϫ33.0 Ϯ 21.8 and Ϫ14.8 Ϯ 18.9%, respectively; P Ͻ 0.001). A reduction of Mmax amplitude was observed only on soleus, and no low-frequency fatigue was observed for any muscle group. Finally, KE maximal force production ability was reduced to a moderate extent at the end of the 24TR (Ϫ10.2%; P Ͻ 0.001), but these alterations were highly variable ( Ϯ 15.7%). These results suggest that central factors are mainly responsible for the large maximal muscle torque reduction after ultraendurance running, especially on the KE muscles. Neural drive reduction may have contributed to the relative preservation of peripheral function and also affected the evolution of the running speed during the 24TR. activation level; M wave; low-frequency fatigue; ultramarathon

European Journal of Applied Physiology, 2015

sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressively decreased (P < 0.05). m. triceps brachii and m. latissimus dorsi were highly desaturated already after the first sprint (all P < 0.05), whereas the response was delayed for m. biceps brachii and m. vastus lateralis. Correspondingly, increases in VO 2 mainly occurred over the first two sprints (P < 0.05) and plateaued at approximately 75 % of VO 2peak . 1RM correlated with power during the first four sprints and with average sprint power (r = 0.71-0.80, all P < 0.05), whereas VO 2peak correlated with power in the last three sprints (r = 0.60-0.71, all P < 0.05). Conclusions The main decrement in upper-body sprint performance was evident in the first five sprints, followed by highly desaturated muscles and a plateau in pulmonary oxygen uptake already after the first 2-3 sprints. While high maximal strength seems important for producing power, aerobic capacity correlates with power in the last sprints.

European journal of applied physiology, 2018

To examine the effects of exercise-induced trunk fatigue on double poling performance, physiological responses and trunk strength in cross-country skiers. Sixteen well-trained male cross-country skiers completed two identical pre- and post-performance tests, separated by either a 25-min trunk fatiguing exercise sequence or rest period in a randomized, controlled cross-over design. Performance tests consisted of a maximal trunk flexion and extension test, followed by a 3-min double poling (DP) test on a ski ergometer. Peak torque during isometric trunk flexion (- 66%, p &lt; .001) and extension (- 7.4%, p = .03) decreased in the fatigue relative to the control condition. Mean external power output during DP decreased by 14% (p &lt; .001) and could be attributed both to reduced work per cycle (- 9%, p = .019) and a reduced cycle rate (- 6%, p = .06). Coinciding physiological changes in peak oxygen uptake (- 6%, p &lt; .001) and peak ventilation (- 7%, p &lt; .001) could be observed. S...

European Journal of Applied Physiology, 2007

The aim of the present study was to examine muscle mechanical characteristics before and after a marathon race. Eight elite runners underwent a pre-test 1 week before the marathon and post-tests 30 min, two and fiveday-post-marathon. Actual marathon race performance was 2:34:40 ± 0:04:13. Energy expenditure at marathon pace (EE Mpace ) was elevated 4% post-marathon (pre: 4,465 ± 91 vs. post 4,638 ± 91 J kg bodyweight -1 km -1 , P < 0.05), but was lowered by 6 and 9.5% two-and five-day-postmarathon compared to EE Mpace pre-marathon. Countermovement jump (CMJ) power decreased 13% post-marathon (pre: 21.5 ± 0.9 vs. post: 18.9 ± 1.2 W kg -1 ; P < 0.05) and remained depressed two-(18%) and five-day (12%) post-marathon. CMJ force was unaltered across all four tests occasions. Knee extensor and plantar flexor maximal voluntary contraction (MVC) decreased from 176.6 ± 9.5 to 136.7 ± 16.8 Nm and 144.9 ± 8.7 to 119.2 ± 15.1 Nm post-marathon corresponding to 22 and 17%, respectively (P < 0.05). No significant changes were detected in evoked contractile parameters, except a 25% increase in force at 5 Hz, and low frequency fatigue was not observed. In conclusion, leg muscle power decreased acutely post-marathon race and recovered very slowly. The post-marathon increase in EE Mpace might be attributed to a reduction in stretch shortening cycle efficiency. Finally, since MVC was reduced after the marathon race without any marked changes in evoked muscle contractile properties, the strength fatigue experienced by the subjects in this study seems to be related to central rather than peripheral mechanisms.

European Journal of Applied Physiology, 2005

This study analyses the changes in the electromyographic activity (EMG) of six major muscles of the leg during an incremental running test carried out on a treadmill. These muscles, the gluteus maximus (GM), biceps femoris (BF), vastus lateralis (VL), rectus femoris (RF), tibialis anterior (TA) and gastrocnemius (Ga) are known to have quite different functions during running. The aim of this study was to develop a methodology adapted to the analysis of integrated EMG (iEMG) running results, and to test the chronology of the onset of fatigue of the major muscles involved in running. Nine well-trained subjects [VO2max 76 (2.9) ml.min_1.kg_1] took part in this study. They completed a running protocol consisting of 4 min stages, incrementally increasing in speed until exhaustion. The EMG signal was recorded during ten bursts of activation analysed separately at 45 s and 3 min 40 s of each stage. During running, consideration of the alteration in stride frequency with either an increase in speed or the onset of fatigue appears to be an indispensable part of the assessment of muscular fatigue. This allows the comparison of muscular activation between the various stage speeds by the use of common working units. Distance seems to be the only working unit that allows this comparison and thus the determination of the appearance of fatigue during running. The biarticular hip-mobilising muscles (RF and BF), which present two different bursts of activation during one running cycle, are the muscles that show the earliest signs of fatigue.

European Journal of Applied Physiology

We investigated the changes in constant velocity spring-mass behavior after high intensity sprint fatigue in order to better interpret the results recently reported after ultra-long distance (ULD) exercises. Our hypothesis was that after repeated sprints (RS), subjects may likely experience losses of force such as after ULD, but the necessity to modify their running pattern to attenuate the overall impact at each step (such as after ULD) may not be present. Eleven male subjects performed four sets of five 6-s sprints with 24-s recovery between sprints and 3 min between sets, on a sprint treadmill and on a bicycle ergometer. For each session, their running mechanics and spring-mass characteristics were measured at 10 and 20 km h−1 on an instrumented treadmill before and after RS. Two-way (period and velocity) ANOVAs showed that high-intensity fatigue did not induce any change in the constant velocity running pattern at low or high velocity, after both running and cycling RS, despite significant decreases (P < 0.001) in maximal power (−27.1 ± 8.2% after running RS and −15.4 ± 11.5 % after cycling RS) and knee extensors maximal voluntary force (−18.8 ± 6.7 % after running RS and −15.0 ± 7.6 % after cycling RS). These results bring indirect support to the hypothesis put forward in recent ULD studies that the changes in running mechanics observed after ULD are likely not related to the decrease in strength capabilities, but rather to the necessity for subjects to adopt a protective running pattern.

2013

This study sought to determine the changes in maximal leg power output over the course of a decathlon in order to better understand 1) the event’s functional demands, 2) the muscular mechanical capabilities determining performance in the event, and 3) their relationships with injury risk factors. It was conducted under field conditions during the 2010 French National Combined Events Championships with six national-level athletes and 11 control participants as subjects. No differences in the values for squat jump and cycling sprint were found between tests at the beginning and end of each day (P&gt;0.05), while significantly lower squat jump values at the start of the second day were reported for the control participants (P&lt;0.05). The results suggest that a decathlon does not induce measurable alterations in lower extremity force, velocity or power output affecting performance and that the accumulation of fatigue (and/or neuromuscular fatigue, if any) does not play a major role in...

HAL (Le Centre pour la Communication Scientifique Directe), 1991

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2018

Sport is known to have many positive effects on mental and physical health. High-intensity exercise is considered to decrease muscle strength and induce muscle fatigue, which is associated with a higher risk of injury. In recreational alpine skiers, a decrease of eccentric peak hamstring torque, as an indication of muscle fatigue, occurs even after 1 day of skiing. The popularity of ski mountaineering is increasing enormously, but no studies are available on its effects on muscle strength. Therefore, the present study examined the consequences of ski mountaineering on muscle fatigue of the concentric/eccentric quadriceps and/or hamstrings. In addition, a possible role of myofascial foam rolling in reducing muscle fatigue was evaluated. Fifty recreational ski mountaineers (27 males, 23 females) completed five consecutive tours of ski mountaineering within 1 week. After each day of skiing, participants underwent an isokinetic muscle test assessing the concentric and eccentric muscle s...