Abstract: A treadmill is disclosed having a belt system carried by a platform structure. The platform structure is pivotally mounted at its rear end to a base structure. The platform is supported at its forward end by a spring and a shock absorber which provides a damped resilient response of the belt and platform when a runner's foot lands during running or walking. The shock absorber is of the type which resists movement when the platform is moving in the downward direction, but offers relatively little resistance to upward movement of the platform when the spring returns the platform to a rest position during the time the runner is above the platform and is not forcing the platform down. An auxiliary shock absorber is mounted to damp the response of the platform over a short distance as the platform returns to its rest position.