Fig. 5. Work loops of hip torque vs angle for a typical subject: (A) as a function of frequency; and (B) compared with normal walking. (A) Work loops varied mostly in terms of torque rather than amplitude or contained area. (B) Compared with normal walking at 1.3 m s^-1 (data from Whittle, 1996), isolated leg swinging occurred at a comparable range of torques and angles, although walking occurs at a lower stride frequency of 0.9 Hz and with more work at the hip.