Fig. 3. As acceleration increased, the net work per kg body mass performed during a single step increased at the hip and the ankle. Net work was independent of acceleration at the knee and the tarsometatarsal–phalangeal (TMP) joint. Linear regressions (N=49) are shown for hip, y=0.154x+0.177, r²=0.64, P<0.01; ankle, y=0.192x–0.129, r²=0.84, P<0.01.