Changes in quadriceps muscle activity during sustained recreational alpine skiing

Area of Science:

• Sports Science
• Biomechanics
• Physiology

Background:

• Prolonged recreational alpine skiing leads to physiological changes and inevitable fatigue.
• Understanding muscle activity during skiing is crucial for injury prevention and performance optimization.

Purpose of the Study:

• To investigate the effects of prolonged skiing on muscle recruitment and coordination.
• To analyze changes in electromyography (EMG) signals of vastus lateralis (VL) and rectus femoris (RF) muscles.

Main Methods:

• Six subjects performed 24 standardized ski runs.
• EMG data from VL and RF were collected during initial (PRE) and final (POST) runs.
• Wavelet and principal component analysis quantified EMG signal changes.

Main Results:

• EMG signal frequency content shifted towards lower frequencies in 7/8 cases, notably for the RF on the outside leg.
• Increased outside leg loading and a shift in muscle activity timing towards turn completion were observed post-skiing.
• Specific EMG frequency changes occurred at distinct time points, not throughout the entire turn.

Conclusions:

• General muscular fatigue involving recruitment of additional muscle fibers did not occur.
• EMG frequency and intensity changes in RF and VL are attributed to altered timing and coordination, suggesting a less controlled skiing technique.
• Recreational skiers modify their technique before significant changes in muscle fiber recruitment due to prolonged skiing fatigue.