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Determining The Electromyographic Fatigue Threshold Following a Single Visit Exercise Test
Published on: July 27, 2015
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Fatigue-induced changes in electromyographic activity after repeated racing turns: a pilot study
Mickael Chollet1, Pierre Samozino2, Baptiste Morel2
1Inter-university Laboratory of Human Movement Sciences, Univ. Savoie Mont Blanc, EA 7424, 73000, Chambéry, France. mickael.chollet@univ-smb.fr.
European Journal of Applied Physiology
|December 20, 2024
Summary
Thirty giant slalom (GS) turns significantly reduced knee extensor strength and altered muscle activation patterns in skiers. This indicates neuromuscular fatigue impacts the initiation phase of skiing turns.
Area of Science:
- Sports Science
- Biomechanics
- Exercise Physiology
Background:
- Alpine skiing is a demanding sport requiring repeated, near-maximal lower limb muscle activation.
- Neuromuscular fatigue is a known consequence of such intense physical exertion.
- Electromyographic (EMG) adaptations following maximal-intensity skiing have not been previously studied.
Purpose of the Study:
- To investigate electromyographic (EMG) activity adaptations in lower limb muscles after repeated maximal-intensity giant slalom (GS) skiing.
- To assess changes in maximal isometric knee extensor force following skiing exertion.
Main Methods:
- Six skiers performed a 6-turn section with (FAT) and without (CONT) 30 GS turns.
- Maximal isometric knee extensor force (Fmax) was measured pre- and post-condition.
- On-snow EMG of key leg muscles was analyzed for amplitude (RMS) and frequency (MPF), comparing outside (OL) and inside (IL) legs using statistical parametric mapping (SPM).
Main Results:
- Maximal force (Fmax) decreased significantly after FAT (-20.1%) but not CONT.
- Reduced EMG amplitude (RMS) was observed in specific muscles for both legs during FAT.
- Reduced EMG mean power frequency (MPF) indicated altered motor command, particularly in the turn initiation phase, for both legs during FAT.
Conclusions:
- Thirty GS turns induce significant neuromuscular fatigue, evidenced by decreased maximal force and altered muscle activation patterns.
- Reduced EMG frequency content suggests a compromised motor command, especially during the critical turn initiation phase.
- These findings underscore the necessity of characterizing neuromuscular fatigue in competitive GS skiing.
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