Ankle weight effect on gait: orthotic implications

Oxygen consumption during ambulation was measured in 10 normal subjects wearing ankle weights of 0.91 kg, 1.82 kg, and 2.73 kg, either on the right ankle or bilaterally. Subjects walked at self-selected speeds and oxygen consumption was measured over 1-minute intervals during steady-state walking. Oxygen consumption per unit distance and oxygen consumption rate demonstrated significant positive linear correlations with added weight (P = .001, P = 0.007, respectively). Velocity demonstrated a significant decrease when correlated with added weight (P = 0.03). Multiple regression analysis was used to relate these measures of oxygen consumption rates to velocity, age, and added weight, yielding predictive relationships. Based on these results, the weight of orthoses should be minimized in order to maximize walking velocity and minimize oxygen consumption per unit distance. The advantage of a light-weight, molded plastic ankle-foot orthosis (AFO) over heavier AFO designs is demonstrated by this study.