Shoes alter the spring-like function of the human foot during running

Area of Science:

• Biomechanics
• Human Physiology
• Sports Science

Background:

• Running economy relies on the spring-like function of the legs and feet.
• Concerns exist that modern running shoes may hinder this spring function by reducing muscle contributions.
• Previous research suggested shoes negatively impact foot mechanics.

Purpose of the Study:

• To investigate the effect of running shoes on foot longitudinal arch (LA) motion.
• To examine the activation of intrinsic foot muscles during running with and without shoes.

Main Methods:

• Participants ran on a force-instrumented treadmill.
• Foot kinematics were recorded using motion capture.
• Intrinsic foot muscle activation was measured using intramuscular electromyography (EMG).

Main Results:

• Running shoes increased peak and total stance muscle activation in intrinsic foot muscles (e.g., flexor digitorum brevis, abductor hallucis).
• Increased muscle activation corresponded with a significant reduction in longitudinal arch (LA) compression.
• Findings contradict previous assertions of impaired foot function in running shoes.

Conclusions:

• Running shoes influence the mechanical function of the foot.
• These mechanical adjustments appear to result from increased neuromuscular output, not impaired control.
• A novel theoretical model for foot-shoe interaction is proposed to explain these findings.