Abstracts Health Sciences

A 60 Second Exposure of Whole Body Vibration has no Effect on Muscular Strength or Vertical Jump Height

by John D Welch

For more than 30 years, researchers have investigated the effects of whole body vibration (WBV) platforms on athletic performance. WBV is a modality in which an individual stands on a vibrating platform to obtain performance effects. Frequency and amplitude of the vibration are the commonly adjusted parameters. The use of WBV as a modality for athletes has gained traction in response to emerging evidence demonstrating significant gains in performance measures including increased jump height and muscular strength. Collective results from several studies suggest a single vibration frequency, optimal vibration frequency (OVF), exists which elicits the greatest effect on performance. However, due to large variations in methodology it remains unknown if an OVF exists and, even more importantly, how OVF for individual athletes should be determined and utilized. There is a need to further identify how various parameters (i.e., frequency or exposure time) impact OVF as a means of enhancing our understanding and utilization of OVF on performance outcomes. The purpose of this study was to determine the WBV frequency that optimizes knee extensor torque and countermovement jump height in physically active adults between 18 and 40 years of age. The central hypothesis was that a single WBV frequency (35 Hz) for optimizing knee extensor torque (KET) and countermovement jump height (CMJ) would be identified. A comparison of KET and CMJ across 1) three independently delivered whole body vibration frequencies and 2) determined if one frequency was associated with greater KET and CMJ to a greater extent than the other frequencies and a control condition. I hypothesized that one of the WBV frequencies would result in greater KET and CMJ when compared to the other frequencies and a control. Additionally, I analyzed the distribution of an individual participants increase in KET and CMJ across three different WBV frequencies. I hypothesized that a greater number of participants would exhibit a larger increase in KET and CMJ after a 60 second exposure of whole body vibration at 35 Hz. Twenty-six recreationally active adults performed pre and posttest isometric KET and CMJ after a 60 second exposure of WBV at a specific frequency. From recorded KET and CMJ height, the largest value from the trials were calculated. There were no changes in KET or CMJ after WBV treatments when compared to pretest and control values. The results suggest that a 60 second exposure of WBV has no effect on maximal KET or CMJ when coupled with a 2-hour rest period. It could be suggested that the compounding of multiple frequencies and increased exposure time within a short time period could produce an effect. To better understand if WBV affects performance, incrementally increasing exposure length with a washout period and a signal that accounts for all frequencies at once warrants being studied. Advisors/Committee Members: Hoffman, Mark (advisor), Norcross, Marc (committee member).