Previous research suggests that specific preconditioning activities such as whole-body vibration (WBV) and resistance training may play an important role in ensuing dynamic activities. The purpose of this study was to examine the effects of 2 preconditioning activities, WBV and power cleans (PC), on acute sprint performance. Two studies were conducted in which 14 (WBV) and 9 (PC) male track and field athletes were subjects. The WBV treatment consisted of 4 bouts of 5 seconds of high-knee running on a vibrating platform at 0, 30, 40, or 50 Hz. The PC treatment consisted of 3 PC reps at 90% 1RM. In both cases, acute sprint performance was the dependent variable of interest. For WBV, split times were recorded at 10, 20, and 40 m. Reaction times (RXN) as well as 5-, 10-, and 40-m split times were recorded for the PC study. Results indicated no significant differences between treatment and nontreatment groups for both studies. However, significant correlations were present between RXN and 5-m splits (r = 0.65) and RXN and 10-m splits (r = 0.63), although they decreased as a function of sprint distance to r = 0.43 at 40 m. These results suggest little efficacy for the use of WBV and PC as a means of augmenting acute sprint performance. However, a trend within the 30-Hz protocol may suggest that WBV as part of a warm-up for sprinting activities greater than 40 m (i.e., 100 m) could potentially result in a decreased sprint time of nearly 1/10th of a second, which is worth future consideration.

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INTRODUCTION:The neuromuscular system assists with ankle stabilization during unexpected perturbation of the ankle. However, few studies have investigated the neuromuscular response to sudden ankle perturbation during gait. A deeper understanding of the neuromuscular response to dynamic ankle perturbations could provide insight into ankle sprain injury avoidance strategies. PURPOSE: To compare lower extremity muscle activity across perturbed and normal walking gait conditions. METHODS: 11 healthy volunteers walked along a walkway embedded with two trapdoors that elicit sudden inversion, or inversion and plantarflexion. Participants performed trials of walking gait during normal walking (NW), inversion (INV), and inversion/plantarflexion (PF) conditions. EMG was collected on the dominant peroneus longus, tibialis anterior, soleus, gluteus medius, and contralateral gluteus medius. Peak EMG (pEMG) was calculated in the 200ms after heel strike of the dominant limb. Data were normalized to the maximal voluntary contraction for each muscle. Repeated measures ANOVAs assessed differences in peak activation of each muscle across conditions. RESULTS: No significant differences in pEMG were found across conditions for any of the muscles [