Fig. 5. Mean joint work in ramp gait across all subjects. Values are means ± s.d. Knee muscles were the primary energy dissipaters in ramp descent, performing 58% and 81% of the negative and net muscular work, respectively. Ankle and hip muscles were the primary energy generators in ramp ascent combining to perform 86% and 95% of the positive and net work, respectively. Negative work in ramp ascent was relatively evenly distributed among the muscle groups, whereas positive work in descent was produced primarily (i.e. 62%) by the ankle muscles.