ANKLE RESISTANCE TRAINING, POSTURAL STABILITY & STEPPING 643

Abstract

This study was performed to assess the effect of a resistance training program targeted to the ankle on postural stability and the ability to step onto a raised surface in elderly (70.5±3.0 yrs; mean±S.D.) men and women after 8 wks of training. Dorsiflexor (DF) and plantarflexor (PF) strength was assessed using peak isokinetic torque during 1-RM at 90°/s on a Cybex II™ isokinetic dynamometer. Postural stability was assessed during quiet standing and one-legged standing on a force platform. The subjects completed 3 walking trials in which they stepped onto a 17 cm platform. Each trial was filmed from a sagittal view. Subjects were randomly divided into training (TR; n=9) or control (CON; n=8) groups. The CON group was asked not to change their lifestyle over the 8 wks of the study. Training consisted of 8 exercise, designed to isolate the PF and DF muscle groups. Subjects performed 3 sets of 8-12 repetitions on each exercise 3x/wk. CON significantly (p<0.05) increased DF torque (15±7 vs. 17±5 Nm) but showed no change in PF torque (52±38 vs. 50±34 Nm). TR showed no change in DF torque (21±9 vs. 21±8 Nm) but significantly (p<0.05) increased PF torque (52±25 vs. 63±26 Nm). No significant differences were found in stability measures. Kinematic analysis of the stepping task for 4 subjects indicated that neither group altered strategy for clearing a step after the 8 week period. To accommodate a less dorsiflexed ankle TR chose to lift the foot higher over the step. CON chose a lower clearance height with the ankle more dorsiflexed to cross the step. It was concluded that targeted training of the PF and DF muscle groups did not affect postural stability and had a limited effect on stepping gait.Table