Repeated practice runs during on-snow training do not generate any measurable neuromuscular alterations in elite alpine skiers.

Autor:	Alhammoud M; Aspetar-Orthopaedic and Sports Medicine Hospital, Doha, Qatar.; French Ski Federation, Annecy, France., Girard O; School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, WA, Australia., Hansen C; Department of Neurology, Christian-Albrechts-Universität zu Kiel Medizinische Fakultat, Kiel, Germany., Racinais S; Aspetar-Orthopaedic and Sports Medicine Hospital, Doha, Qatar., Meyer F; Digital Signal Processing Group, Department of Informatics, University of Oslo, Oslo, Norway., Hautier CA; Inter-University Laboratory of Human Movement Biology, University Claude Bernard Lyon 1, Lyon, France., Morel B; Inter-University Laboratory of Human Movement Biology (EA 7424), Savoie Mont Blanc University, Chambéry, France.
Jazyk:	angličtina
Zdroj:	Frontiers in sports and active living [Front Sports Act Living] 2022 Jul 29; Vol. 4, pp. 829195. Date of Electronic Publication: 2022 Jul 29 (Print Publication: 2022).
DOI:	10.3389/fspor.2022.829195
Abstrakt:	Background: Alpine skiers typically train using repeated practice runs requiring high bursts of muscle activity but there is little field-based evidence characterizing neuromuscular function across successive runs. Purpose: To examine the impact of repeated ski runs on electromyographic activity (EMG) of the knee extensors and flexors in elite alpine skiers. Methods: Nineteen national team alpine skiers were tested during regular ski training [Slalom (SL), Giant Slalom (GS), Super Giant Slalom and Downhill (Speed)] for a total of 39 training sessions. The surface EMG of the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM), biceps femoris (BF) and semimembranosus/semitendinosus (SMST) muscles was continuously recorded along with right knee and hip angles. The EMG root mean square signal was normalized to a maximal voluntary contraction (%MVC). The first and fourth runs of the training session were compared. Results: There was no meaningful main effect of run on EMG relative activation time or mean power frequency beyond the skier's intrinsic variability. However, EMG activity of the vastii increased from the first to the fourth run in SL [VM, ~+3%MVC for IL and outside leg (OL), p = 0.035)], speed (VL, IL:+6%/OL:+11%, p = 0.015), and GS (VM, IL:0/OL:+7%, p < 0.001); the later with an interaction with leg ( p < 0.001) due to a localized increase on the OL. The run time and turn time did not change from the first to the fourth run. There were no meaningful changes in angular velocities, amplitude of movement, or maximal and minimal angles. Conclusion: Neuromuscular activity remains highly stable in elite skiers with low variability across four runs. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2022 Alhammoud, Girard, Hansen, Racinais, Meyer, Hautier and Morel.)
Databáze:	MEDLINE
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