The effect of plyometric training on peroneal latency.

CONTEXT: Peroneal reaction to sudden inversion has been determined to be too slow to overcome the joint motion. A focused plyometric training program may decrease the muscle's reaction time.

OBJECTIVE: To determine the effect of a 6-wk plyometric training program on peroneus longus reaction time.

DESIGN: Repeated measures.

SETTING: University research laboratory.

PARTICIPANTS: 48 healthy volunteers (age 20.0+/-1.2 y, height 176.1+/-16.9 cm, weight 74.5+/-27.9 kg) from a large Midwestern university. Subjects were randomly assigned to either a training group or a control group.

INTERVENTIONS: Independent variables were group at 2 levels (training and no training) and time at 2 levels (pretest and posttest). The dependent variable was peroneal latency measured with surface electromyography. A custom-made trapdoor device capable of inverting the ankle to 30 degrees was also used. Latency data were obtained from the time the trapdoor dropped until the peroneus longus muscle activated. Peroneal latency was measured before and after the 6-wk training period. The no-training group was instructed to maintain current activities. The training group performed a 6-wk plyometric protocol 3 times weekly. Data were examined with a repeated-measures ANOVA with 1 within-subject factor (time at 2 levels) and 1 between-subjects factor (group at 2 levels). A priori alpha level was set at P
MAIN OUTCOME MEASURES: Pretest and posttest latency measurements (ms) were recorded for the peroneus longus muscle.

RESULTS: The study found no significant group-by-time interaction (F1,46=0.03, P=.87). In addition, there was no difference between the pretest and posttest values (pretest=61.76+/-14.81 ms, posttest=59.24+/-12.28 ms; P=.18) and no difference between the training and no-training groups (training group=59.10+/-12.18 ms, no-training group=61.79+/-15.18 ms; P=.43).

CONCLUSIONS: Although latency measurements were consistent with previous studies, the plyometric training program did not cause significant change in the peroneus longus reaction time.