Stability of dynamic trunk movement.

Study Design: Nonlinear systems analyses of trunk kinematics were performed to estimate control of dynamic stability during repetitive flexion and extension movements.

Objective: Determine whether movement pace and movement direction of dynamic trunk flexion and extension influence control of local dynamic stability.

Summary Of Background Data: Spinal stability has been previously characterized in static, but not in dynamic movements.

The influence of gait speed on local dynamic stability of walking.

The focus of this study was to examine the role of walking velocity in stability during normal gait. Local dynamic stability was quantified through the use of maximum finite-time Lyapunov exponents, lambda(Max). These quantify the rate of attenuation of kinematic variability of joint angle data recorded as subjects walked on a motorized treadmill at 20%, 40%, 60%, and 80% of the Froude velocity.