Stance width influences frontal plane balance responses to centripetal accelerations

Area of Science:

• Biomechanics
• Human motor control
• Vestibular system function

Background:

• Curvilinear motion generates inertial torques requiring counteraction for stability.
• The body's ability to maintain balance involves complex sensorimotor integration.

Purpose of the Study:

• To test if healthy subjects position their center of mass to balance inertial and gravitational torques during rotation.
• Investigate the influence of stance width, visual input, and rotation speed on body orientation.

Main Methods:

• Ten healthy subjects stood on a rotating platform under varying conditions (speed, vision, stance).
• Measured upper body, lower body, and center of mass (CoM) tilt relative to vertical.
• Compared body tilt to the gravito-inertial acceleration (GIA) angle.

Main Results:

• Inward body tilt was observed across all conditions but did not fully match the predicted GIA angle.
• CoM tilt reached approximately 78% and 39% of the GIA angle in narrow and wide stances, respectively.
• Stance width had a greater effect on body tilt than visual availability or acceleration magnitude.

Conclusions:

• The base of support is crucial for balance control strategies during rotational movement.
• Understanding how the balance system compensates for inertial torques is enhanced by these findings.