The purpose of this 6-wk study was to determine the effects of dynamic contractions supplemented with electromyo-stimulation (EMS) employed during a weight lifting exercise on knee extensor strength and vertical jump performance. Twenty female college track & field athletes were randomly assigned to 1 of 4 groups: non-weight-training/non-EMS (Control); weight-training-only (Wgt); EMS-only (Stim); and weight training + EMS (Wgt + Stim). All groups were pre-and posttested for knee extensor strength (1-RM) and vertical jump height (cm) using the bilateral knee extension exercise and countermovement vertical jump (VJ). The Wgt and Wgt + Stim groups trained 3 times a week at 85% of their 1-RM employing 3 sets of 8-10 reps; the Stim received EMS 3 times a week. Strength and VJ increased for all 4 groups. The 3 experimental groups differed significantly (p < 0.05) from Controls for both strength and VJ. Also, Wgt + Stim differed significantly from Wgt and Stim, while Wgt differed significantly only from Stim. These results suggest that supplementing dynamic contractions with EMS appears more effective than EMS only, or weight training only, for increasing knee extensor strength and VJ in female track & field athletes.
(C) 1998 National Strength and Conditioning Association