Muscle synergies are consistent when pedaling under different biomechanical demands

Area of Science:

• Biomechanics
• Motor Control
• Human Physiology

Background:

• Muscle synergies are fundamental building blocks of motor control.
• Understanding muscle coordination during cycling is crucial for performance and injury prevention.

Purpose of the Study:

• To investigate muscle coordination during pedaling using the muscle synergies paradigm.
• To compare muscle synergies between a preferred pedaling strategy and an optimized strategy.
• To determine if motor control exhibits modularity during cycling.

Main Methods:

• Electromyography (EMG) was used to record activity from 8 leg muscles in 9 participants.
• Nonnegative Matrix Factorization (NMF) was applied to extract muscle synergies.
• Participants performed cycling with a preferred strategy and an optimized strategy using real-time feedback on mechanical efficiency.

Main Results:

• Four muscle synergies were sufficient to represent muscle activity during the preferred pedaling strategy, consistent across participants.
• Five muscle synergies were needed for the optimized pedaling strategy.
• Four of the five synergies were shared between the preferred and optimized strategies, with one additional subject-specific synergy emerging in the optimized condition.

Conclusions:

• The findings support the hypothesis of a modular motor control system in humans during pedaling.
• Pedaling optimization may involve the recruitment of specific, potentially subject-specific, muscle synergy modules.
• This research provides insights into the adaptability of motor control strategies in response to biomechanical demands.