Association between Muscle Synergy and Stability during Prolonged Walking

Area of Science:

• Biomechanics
• Human Movement Science
• Neuromuscular Physiology

Background:

• Gait stability is crucial for preventing falls and maintaining mobility.
• Understanding how muscle activity and coordination change with fatigue is essential for injury prevention and rehabilitation.

Purpose of the Study:

• To investigate the effects of prolonged walking on muscle synergy and gait stability.
• To compare muscle activity patterns and coordination before and after a 90-minute walking bout.

Main Methods:

• Twelve healthy males walked on a treadmill for 90 minutes at 4.5 km/h.
• Electromyographic (EMG) data from 7 leg muscles were recorded.
• Principal component analysis (PCA) assessed muscle coordination patterns.
• Local dynamic stability was quantified using the largest Lyapunov exponent.

Main Results:

• Muscle synergy patterns did not change significantly over time.
• Triceps surae co-activation increased, and medial gastrocnemius iEMG decreased after prolonged walking.
• Gait stability, measured by the largest Lyapunov exponent, decreased in both mediolateral and anteroposterior directions.

Conclusions:

• Increased triceps surae co-activation after prolonged walking may be linked to reduced gait stability.
• Fatigue-induced changes in muscle recruitment patterns can compromise balance control.