In a previous paper (Neptune & Hull, 1995), a new video-based method (ASIS) for locating the hip joint center (HJC) in seated cycling was shown to be more accurate than tracking a marker placed over the superior aspect of the greater trochanter (TRO). The main goal of the present study was to see if the conclusions presented in Neptune and Hull (1995) may be applied to other cyclists. Lower limb kinematic and pedal force data were collected from 7 cyclists at nine combinations of pedaling rate and work rate. ASIS produced significantly different hip joint movement patterns than TRO, which resulted in significantly different power and work calculations developed by the intersegmental hip joint force, at all combinations except one. A significant quadratic trend was evident as a function of pedaling rate, and a significant linear trend was evident for work rate. At naturally preferred pedaling rates (~90 rpm) and lower work rates (<225 W), the hip joint movement was minimum. Under these conditions, the fixed hip assumption is least prone to error.
The authors are with the Department of Mechanical Engineering, University of California, Davis, CA 95616. Direct correspondence to M.L. Hull.