Decreased foot inversion force and increased plantar surface after maximal incremental running exercise

Area of Science:

• Sports Medicine
• Biomechanics
• Exercise Physiology

Background:

• Maximal running exercise may induce fatigue in specific foot muscles.
• Understanding muscle fatigue and postural changes post-exercise is crucial for injury prevention.

Purpose of the Study:

• To investigate electromyographic (EMG) signs of fatigue in the tibialis anterior (TA), peroneus longus (PL), and gastrocnemius medialis (GM) muscles after maximal running.
• To assess post-exercise alterations in stationary upright standing posture.

Main Methods:

• Healthy subjects performed maximal running exercise.
• Surface EMG of TA, PL, and GM muscles were analyzed during dynamic efforts.
• Measurements included M-wave in TA, maximal voluntary contraction (MVC) into inversion, and plantar pressure distribution.

Main Results:

• EMG spectral analysis revealed a decline in median frequency for the TA muscle, indicating fatigue.
• Maximal voluntary contraction into inversion (MIF) decreased post-exercise.
• Increased rearfoot plantar surface and barycentre surface areas suggested a shift towards foot eversion during standing.

Conclusions:

• Maximal running exercise induces fatigue specifically in the tibialis anterior muscle.
• Post-exercise, a change in foot posture towards eversion was observed during static standing.
• Findings are specific to maximal running and may not apply to lower-intensity activities.