Daniel H. Serravite

Displacement and frequency for maximizing power output resulting from a bout of whole-body vibration.

Bedient, AM, Adams, JB, Edwards, DA, Serravite, DH, Huntsman, E, Mow, SE, Roos, BA, and Signorile, JF. Displacement and frequency for maximizing power output resulting from a bout of whole-body vibration. J Strength Cond Res 23(6): 1683-1687, 2009-Whole-body vibration (WBV) has been shown to be effective for increasing lower-body power; however, the combination of frequency, displacement, and duration that elicits the best acute response has yet to be determined. The purpose of this study was to identify the protocol eliciting the greatest improvement in power after an acute bout of WBV. Forty men and women participated in this study, in which 8 different combinations of 30, 35, 40, and 50 Hz with 2-mm and 5-mm displacements were tested over 3 days. For all protocols, randomized to reduce potential order effects, subjects underwent 30 seconds of WBV while holding an isometric squat at a knee angle of 2.27 rad. Power was assessed by countermovement jumps. Subjects performed 3 jumps before WBV, immediately afterward, and 1, 5, and 10 minutes later. The highest normalized peak power (nPP) at each time point was determined using a 4 (frequency) × 2 (displacement) × 5 (time) repeated-measures analysis of variance. Significant effects were seen for frequency (p ≤ 0.026) and time (p ≤ .0001). Post hoc analyses revealed that the 30-Hz condition (1.010 ± 0.003) produced a higher nPP than 35 Hz (1.00 ± 0.003, p ≤ 0.026) and 40 Hz (1.002 ± 0.002, p ≤ 0.028) but not 50 Hz (1.004 ± .002). We also found a significantly higher nPP for the 1-minute post-treatment time point (1.011 ± .0003) vs. all other time points (p ≤ 0.006). Our data show that an acute WBV bout can significantly increase power output at 1 minute post-treatment across all frequencies and displacements, although 30 Hz appears to have a greater effect on power output than either 35 Hz or 40 Hz, but not 50 Hz, at all post-treatment time points.

Effect of Whole-Body Periodic Acceleration on Exercise-Induced Muscle Damage After Eccentric Exercise

PURPOSE To examine the effects of whole-body periodic acceleration (pGz) on exercise-induced-muscle-damage (EIMD) -related symptoms induced by unaccustomed eccentric arm exercise. METHODS Seventeen active young men (23.4 ± 4.6 y) made 6 visits to the research facility over a 2-wk period. On day 1, subjects performed a 1-repetition-maximum (1RM) elbow-flexion test and were randomly assigned to the pGz (n = 8) or control group (n = 9). Criterion measurements were taken on day 2, before and immediately after performance of the eccentric-exercise protocol (10 sets, 10 repetitions using 120% 1RM) and after the recovery period. During subsequent sessions (24, 48, 72, and 96 h) these data were collected before pGz or passive recovery. Measurements included isometric strength (maximal voluntary contraction [MVC]), blood markers (creatine kinase, myoglobin, IL-6, TNF-α, TBARS, PGF2α, protein carbonyls, uric acid, and nitrites), soreness, pain, circumference, and range of motion (ROM). RESULTS Significantly higher MVC values were seen for pGz throughout the recovery period. Within-group differences were seen in myoglobin, IL-6, IL-10, protein carbonyls, soreness, pain, circumference, and ROM showing small negative responses and rapid recovery for the pGz condition. CONCLUSION Our results demonstrate that pGz can be an effective tool for the reduction of EIMD and may contribute to the training-adaptation cycle by speeding up the recovery of the body due to its performance-loss-lessening effect.