Kinematic analyses of semireclined leg cycling in able-bodied and spinal cord injured individuals

Study design: Retrospective descriptive study. Objectives: To evaluate the leg kinematics and motion characteristics within able-bodied ( AB) and spinal cord injured (SCI) individuals during stationary semireclined cycling. Setting: Functional Performance Laboratory, Connecticut, USA. Methods: Three SCI and three AB subjects participated in steady-state leg pedaling ( 50 revolutions per minute). The SCI group participated in electrical stimulation (FES)-induced cycling at resistances of 0, 6.25, and 12.5 Watts ( W). The AB group cycled on the same ergometer without FES at resistances of 0, 60, and 120 W. Motion capture analysis recorded joint angular position, velocity, and acceleration at hip, knee, and ankle. Joint kinematics of hip, knee, and ankle were measured during steady-state leg cycling and comparisons were made between AB and SCI subjects as resistance proportionally and relatively increased. Results: Intrasubject hip and knee movement patterns showed minimal variability across resistance levels. Comparisons between AB and SCI subjects showed that the hip and knee kinematics were very similar at all resistance levels. However, ankle movement patterns appeared to increase in variability ( increased dorsiflexion) with increased resistance level in AB subjects and less so with SCI subjects. Overall, the ankle kinematics for AB and SCI subjects were dissimilar at resistance levels greater than zero. Conclusions: The joint kinematics of the hip, knee, and ankle were found to be periodic, but the differences in ankle kinematics in AB and SCI subjects suggest more emphasise should be placed on the current design of the bike-pedal and subject-specific seat configurations.