On voluntary rhythmic leg movement behaviour and control during pedalling.

Area of Science:

• Human motor control
• Exercise physiology
• Biomechanics

Background:

• Voluntary rhythmic leg movement, exemplified by pedalling, is crucial for activities like cycling.
• Freely chosen pedalling frequency is typically higher than the energetically optimal frequency, leading to lower efficiency.
• Understanding the control mechanisms of freely chosen pedalling frequency is important for optimizing performance and training.

Purpose of the Study:

• To investigate the behavior and control of voluntary human rhythmic leg movement, using pedalling as a model.
• To examine how factors like cardiopulmonary loading, fatiguing exercise, and strength training affect pedalling characteristics.
• To characterize freely chosen pedalling frequency in terms of individuality, stability, and influencing factors.

Main Methods:

• Experimental studies involving healthy individuals and trained cyclists.
• Application of cardiopulmonary and mechanical loading, fatiguing hip extension/flexion exercises, and heavy strength training.
• Analysis of pedalling frequency, pedal force, and physiological variables (e.g., VO2).

Main Results:

• Freely chosen pedalling frequency is highly individual, stable over time, and generally unaffected by fatiguing exercises or cardiopulmonary loading.
• Pedalling frequency increases with higher power output and decreases after heavy strength training, particularly hip extension training.
• Fatiguing hip flexion exercise alters the tangential pedal force profile, indicating changes in the movement pattern, but not the frequency.

Conclusions:

• Freely chosen pedalling frequency is a robust, innate motor rhythm primarily influenced by central pattern generators.
• Strength training, especially hip extension, can modify pedalling frequency, suggesting neural adaptations impacting movement rhythm control.
• The findings contribute to understanding the complex interplay between central control, peripheral feedback, and external factors in rhythmic leg movements.