How Our Body Keeps Its Balance When Standing vs Walking

Your body stays upright using reflexes and feedback. These mechanisms work together in standing and walking. A simple model can capture their combined effect. It links delayed position and velocity of the center of mass to ground forces. It is not known if the model's parameters change with the task.

Fifteen young adults participated. They walked at 1.25 m/s for five minutes. Then they did three standing tasks. The tasks were normal stance, one‑leg stance, and a step posture. Each task lasted one minute and was repeated five times. Researchers measured body motion and floor forces. They used the data to fit the model and find delay and gain values.

The model fit better for standing than for walking. Side‑to‑side delay was longer in walking. Front‑to‑back delay was similar. Position gains were mostly above a critical level. Only the average walking gain was below it. All velocity gains were under‑damped. In standing, the ratio of position to velocity gain matched the body's natural pendulum frequency. In walking, the ratio was close to that frequency when stabilization mattered.

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