Date of Award

January 2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Kinesiology & Public Health Education

First Advisor

Joshua Guggenheimer

Abstract

Purpose: Despite the catabolic effect of cortisol on bone metabolism, and the potentially counteracting anabolic effect of whole body vibration (WBV) on bone, only a few studies have explored the effects of WBV on cortisol, the findings of which have

been inconclusive. Therefore, the purpose of this study was to determine the effect of an acute bout of WBV on salivary cortisol levels in women. Method: This study utilized a randomized cross-over design, consisting of two individual treatment days: the vibration

intervention (V) and the non-vibration control (NV), with a washout period of 2-3 days between the two. Participants consisted of a convergence sample 12 women (19 to 30 yrs. old) with varying levels of physical activity. WBV consisted of a 30-sec bout of isometric

squatting with 1100 knee flexion followed by 30-sec rest. WBV parameters were set to a frequency of 30 HZ and an amplitude of 4 mm. Saliva was sampled both before and immediately after exposure to each of the conditions. Differences between pre- and posttest values for each condition were compared using a paired samples t-test. Significance was set at p < 0.05; with a 95% confidence interval.

Results: paired-samples t-tests for both the experimental and the control group showed no significant difference between pre- and post-test data (t (13) = 0.154, p = 0.88, and t (13) = -11.314, p =0.451). Discussion: The main finding of this study was that an

acute bout of WBV did not appear to have a significant influence on salivary cortisol. It may have been that the chosen volume of WBV was inadequate to provide a significant stimulus to result in an endocrine response. Future WBV research should be focused on determining the optimal workload needed to induce hormonal changes in both women and men.

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