INFLUENCE OF VELOCITY AND CONTRACTION ORDER ON TORQUE PRODUCTION IN OLDER ADULTS WITH TRAINING 981

Abstract

The purpose was to investigate the effects of exercise velocity on stretch-shortening cycles of concentric (CONC) and eccentric (ECC) dorsiflexor(DF) and plantar flexor (PF) torque production in older adults. Twenty-two men and women volunteers ([horizontal bar over]x age = 74.8 ± 3.9 years) completed 2 weeks, 3 sessions/week, of DF and PF isokinetic exercise at 30, 90 and 180°/sec on a KIN COM. Isokinetic training involved one set of 6 maximum voluntary contractions (MVC)/session at the three velocities for CONC/ECC and ECC/CONC DF and PF exercise. Repeated measures analyses of variance were calculated to determine statistical significance. Baseline torque values prior to resistance training were not significantly different between CONC/ECC versus ECC/CONC ankle DF or PF. Post-training results demonstrated a significant increase (31.0%, p<.05) in DF ECC torque at 180°/sec when preceded by a CONC contraction. DF CONC torque was also significant at 180°/sec after training but decreased in value (24.4%, p<.05) when following an ECC contraction. No potentiation by contraction order for PF ECC or CONC torque at any velocity was found pre- or post-training. The decrease in CONC DF torque may be secondary to the fatiguing effects of preceding ECC contractions. The pre-shortened passive components before ECC DF contraction may be contributing to enhanced ECC torque during DF lengthening.