Researchers from the Institute of Sport and Recreation Research, Faculty of Health and Environmental Science and Auckland University of Technology in New Zealand conducted a review of existing research and their findings are published in the March 2009 (Volume 23, Number 2) edition of the National Strength and Conditioning Association’s Journal of Strength and Conditioning Research.
In an earlier article I discussed the researchers’ conclusion that WBV does not enhance speed. However, in a paper titled “Vibration Training: Could it Enhance the Strength, Power or Speed of Athletes?” the researchers found a lack of reliable evidence to support the use of WBV in other areas, as well.
Online access to the journal is provided for NSCA members only.
A common claims made in sales materials and web sites is that WBV training has a positive impact on hormonal levels, specifically that testosterone and human growth hormone (HGH) levels are raised as a result of standing on these vibrating platforms. The authors of this review discuss the results of three studies that have been done to determine the effect WBV has on the endocrine system.
A study conducted by Kvorning et al (“Effects of Vibration and Resistance Training on Neuromuscular and Hormonal Measures”, 2006) combined exercise with vibration to determine if WBV had a positive effect on the endocrine system. Twenty-eight untrained subjects were split into three groups: vibration-only, vibration and body weight squats, and body weight squats only. Testosterone levels increased similarly for the vibration/squat group and the squat-only group and there was no increase seen in the vibration-only group.
These findings are in line with two other studies. DiLoreto et al (“Effects of Whole Body Vibration Exercise on the Endocrine System of Healthy Men,” 2004) saw no increase in testosterone or HGH levels in 10 men who stood on a WBV platform for 25 minutes and Bosco (“Hormonal Responses to Whole Body Vibration in Men,” 2000) observed an increased in HGH and smaller increase in testosterone for subjects who squatted on a vibrating platform.
The findings of these researchers in this review of current and reliable studies stand in stark contrast to the claims made by companies marketing WBV platforms.
With regard to improving an athlete’s strength the authors of this review analyzed five studies; three studies observed strength benefits and two studies found no benefits. The authors of this review found a variety of study design inconsistencies that call into question the positive results.
The first study looked at sprinters; one group engaged in their regular training and performed dynamic exercises on a WBV platform while the control group just performed regular sprint training. The authors of this review wrote, “It could be expected that the WBV group would have a small strength gain compared with the control group purely because of the extra 27-53 minutes of training that this group performed each week.” Since the control group did not perform any strength training exercises the design of the study virtually guaranteed the WBV group would show an improvement in strength.
The authors also point out the obvious problem with the method of strength measurement used in this study. “Transferability of WBV training to the testing protocol in this study is questionable because they comprised different movements.” The sprinters performed squat exercises and were tested with leg-extension exercises.
The authors of the review had problems with the other studies in this group as well, writing that the validity of strength measures was questionable due to the method used to measure strength. In another study there was “no overall significant benefit (a trivial 1% decrement) to maximal squat strength after 6 weeks of vibration training compared to non-vibration group.”
The authors conclude the section on strength training and WBV by writing, “Only when further well-designed studies are conducted will we be able to make any conclusive statement about the potential efficacy of vibration training in enhancing strength of trained athletes.” The words of these scientific experts – again – stand in opposition to the hype offered up by WBV proponents.
In addition to pointing out the problems with the methodology used in WBV studies and concluding that WBV does not improve speed, the authors of this review found that WBV training does not cause any increase in the recruitment of motor units and has no positive effect on human growth hormone and testosterone levels. The best that the researchers can say is that WBV may provide athletes with "variety." So while WBV may do something, that something isn't scientifically verifiable.