RELATIONSHIP OF PLANTAR-FLEXOR PEAK TORQUE AND DORSIFLEXION RANGE OF MOTION TO KINETIC VARIABLES DURING WALKING

Limited ankle plantar-flexor moments and power during walking have been documented in several patient populations and are believed to contribute to gait deviations. The primary purpose of this study was to determine the relationship of plantar-flexor peak torque (PFPT) and dorsiflexion range of motion (ROM) to peak ankle moments and power during walking in a group of subjects without diabetes mellitus (DM) and in a group of subjects with DM and associated peripheral neuropathies. Subjects. Nineteen subjects, 9 with DM and associated peripheral neuropathies (mean age = 58 years, SD = 14, range = 35-75 years) and 10 without DM (mean age = 57 years, SD = 11, range = 37-68 years), were evaluated. Methods. The following data were collected on all subjects: PFPT, dorsiflexion ROM, and ankle moments and power during walking (using a two-dimensional link-segment model). Hierarchical multiple regression was used for data analysis. Results. Plantar-flexor peak torque made substantial contributions to the ankle moment (40%) and ankle plantar-flexor power (53%) during walking. There also was a high correlation between PFPT and dorsiflexion ROM (r = .78) and between dorsiflexion ROM and ankle power (r = .72). Conclusion and Discussion. Plantar-flexor peak torque and dorsiflexion ROM are interrelated and appear to be important factors that contribute to ankle plantar-flexor moments and power during walking. This finding suggests that increasing PFPT and dorsiflexion ROM may help decrease gait deviations such as decreased step length and walking speed. When increasing PFPT is not possible, the natural occurrence of limited dorsiflexion ROM may help to maximize ankle moments during walking. Further research is needed to test whether these proposed treatment strategies can have a clinically useful effect.