Editor’s Note: John T. Weatherly has helped with conditioning programs and research at the U.S. Olympic Training Center in Colorado Springs. John is also a frequent commenter, and now contributor, on the Russells’ Blog. Today’s topic is vibration plates. These plates vibrate like a truck on a highway, supposedly making you fitter. See the video below. Weatherly exposes the unreliable studies that NSCA and others have published on vibration platforms.
On The Take With Power Plate? Part 1
The idea of using a certain dose of vibration in therapy for various conditions has been around a long time. In 2003, the American College of Sports Medicine (ACSM) published a review article by Cardinale and Bosco covering the use of vibration as an exercise modality (2). Vibration is thought to work similar to plyometrics. For example see this video.
For detailed potential mechanisms see Cardinale and Bosco (2) or Donaldson and Ross (4). While vibration can be delivered to the body in various ways (i.e., superimposed on a pulley cable), the review by Drs. Cardinale and Bosco seemed to spur research and commercial interest in the use of vibration platforms or plates. This has been termed whole body vibration (WBV). Scores of WBV studies have been published since 2003. Additionally, WBV platforms are now found in commercial, athletic, rehabilitation, and even military settings (i.e., see powerplate.com). But, what does this WBV research actually say?
To answer the above question, we need to understand there are different types and brands of WBV platforms (4,8). Some move side to side like a teeter-totter (i.e., Galileo), others vertically (i.e., Nemes or the original steel Power Plate), and are even advertised as being tri-planar now (i.e., newer and lighter weight Power Plate). The material the platforms are made of can vary considerably from steel (original Power Plate) to plastic. Regardless of the type or brand, WBV platforms move a certain distance up and down (amplitude) and at a certain frequency or speed. Amplitude is measured in millimeters (mm) while frequency is measured in Hertz (Hz) (8).
Imagine you were a researcher doing a study on a WBV platform. Your untrained subjects range in body weight from 110 to 300 lbs. You are going to train the subjects three times a week for 8 weeks on this WBV platform at a frequency of 40 Hz and 2 mm amplitude. The results of the WBV group will be compared to a sedentary control group at the end of the study. The manufacturer of the WBV platform you are using tells you the platform is accurate for a wide range of loads but you have not seen any independent testing of this particular brand and model of WBV platform in your review of the WBV literature. This seems odd to you as there is information on other devices used to track movements (i.e., 10). See “Validity and reliability of GPS for measuring instantaneous velocity during acceleration, deceleration, and constant motion.”
Are you, as a research scientist, going to do a pilot study and test the WBV platform yourself? Or, perhaps you could have independent engineering tests done on the platform to make sure it works as advertised for a wide range of loads? That would take a lot of time and possibly money to do this though. If you don’t do either of these and there’s no information in the scientific literature about this particular brand and model of platform, you really won’t know if all the subjects in your study are exercising on the WBV platform at a frequency of 40 Hz and amplitude of 2mm. Those WBV platform people sure seem nice. Heck, they may have given you the platform and funds to do the study in the first place. What are you, as a research scientist, going to do?
Reliability and Validity
Any university researcher knows what reliability and validity mean. Reliability, in our example, is the consistency of the WBV platform(s). Imagine stepping on your bathroom scale and weighing 200 lbs only to find out your weight on the same scale is 100 lbs the next day (not reliable!). Validity is simply measuring what we intend to measure. Whenever a device such as a WBV platform is used to collect data we need to be sure the WBV platform performs as it is supposed to so we are measuring what we want to measure. Otherwise, the data collection methods are erroneous and the data analyzed will be invalid.
Research Papers – The Methods Section
So, how do we know if WBV researchers did pilot studies themselves or had independent engineering tests done on the WBV platforms used in their studies? They should state this in the methods section of their peer reviewed journal articles. If other researchers have tested the exact same brand and model of platform and found it reliable and valid, that should be cited. Research papers have four main sections: introduction, methods, results, and discussion. If the methods section does not explain procedures clearly (such as testing WBV platforms under different loads), then the study can’t be replicated and confirmed by other researchers. The data is invalid if nobody tested the WBV platforms under various loads because nobody would know if the data obtained was reliable and valid (just trusting what the manufacturer said).
Studies on Power Plate’s Own Site
I downloaded and read the methods section for all 41 studies on Power Plate’s site. I didn’t see ANY that reported pilot testing or having independent engineering tests performed on the Power Plate WBV platforms used in their studies.
Out of the 41 studies on Power Plate’s own site, I found Roelants (8) et al. and Delecluse (3) et al. measured accelerations of the platform with an accelerometer. Interestingly, these two studies were published in 2004 and 2003. They appear to have been conducted on the older steel Power Plate platforms and not the plastic or light weight models Power Plate has marketed recently. See, “Amplitude is Everything.”
Lowell et al. stated the portable platform used in their study had a limited amplitude (5). Marin et al. reported measurements with a 70 kg load on the platform (6). This Marin et al.(6) study is the only one I found on Power Plate’s site that even mentioned a measurement with a load prior to doing a study. I wonder why Marin et al. (6) chose a 70 kg load instead of 100 kg or other heavier load?
One group of researchers (1, p.238) states:
“A key reason for inconsistencies in scientific data regarding the effects of WBV may be that protocols vary from study to study. Different frequencies and amplitudes have been applied to different populations with varying recovery periods. Each of these parameters has the potential to impart biological response to vibration training and, therefore, the effects of vibration training on strength and power performance.”
Ironically, Adams et al. (1) didn’t mention the platforms themselves. This is peculiar.
How bad has the WBV Research Been?
The WBV research has been so bad that the International Society of Musculoskeletal and Neuronal Interactions had to publish a paper in 2010 on how to conduct WBV studies. Rauch et al. (7, p.193) state:
“A scientific study can lead to scientific progress only if the resulting study report can be understood by others. This requires a common language and consistent use of well-defined terminology. It is also critical that the methodologies of the study is described accurately and with sufficient detail for others to replicate the study.”
It’s shocking to think of all the invalid studies that have contaminated the WBV literature. Here are actual quotes of Power Plate researcher David Bazett-Jones, provided by Vibra-Train’s Lloyd Shaw:
As far as having engineering reports done on the machines, I would argue that it is the ethical responsibility of the manufacturer to do the testing and report the results. The blame is not on the researchers but the manufacturers.
As far as my (Power Plate) study in 2005, we only measured the accelerations (which were different than the manufacturer’s claimed accelerations). This was done without an individual standing on the plate.
I also feel that there are some researchers (myself included) that would like to perform product testing so that consumers can be informed of the specs.
We are testing it loaded and unloaded. Believe it or not, you are not the only one who has wondered if the Power Plate, being made of a softer material than steel, affects the vibration characteristics.
I agree that all plates should be tested before (and while, to go above and beyond) they are being used for a research study…..I can only wish that I had thought of this prior to doing the study.
I am more concerned about the errors/limitations of my research than you are. This was years of planning, testing, and analyzing that I put into this project. I could not account for limitations in the study that I was not aware of at the time.
Where is the Peer Review Process?
Out of 41 studies on Power Plate’s own site, only one mentioned testing the platform under load (70 kg) and that was the only load tested (6). Are we to believe all these researchers and journal reviewers simply missed the elephant standing in the middle of the room? See this video by Lloyd Shaw.
These are supposed to be intelligent and highly trained researchers, right? The 41 studies on Power Plate’s own site represent several journals but the NSCA’s Journal of Strength and Conditioning Research (JSCR) is represented well. I counted 12 studies from JSCR out of the total of 41 studies.
This contamination of the literature has allowed marketers and salespeople to take advantage of the situation amidst all the confusion. For example see this video, contrasted with “Vibration Training: The Truth.”
I have had people on different continents (one a well-known researcher) tell me some Power Plate models lost specifications at 80-85 Kg loads and really bogged down at 100 Kg and above. The Australian Institute of Sport has also reported this in a pilot study (4).
(Next check out Part 2 of John Weatherly’s On the Take With Power Plate?)
About the Author: John T. Weatherly has undergraduate and graduate degrees in exercise science. He was a research assistant to the former Head of Sports Physiology for the US Olympic Committee (USOC) and has helped with conditioning programs for athletes in Olympic sports as well as professional baseball, college football, and an NBA player. In the 90’s, John published and reviewed articles for the NSCA and was an NSCA media contact on the sport of baseball. He helped initiate the first study on a rotary inertia exercise device at the University of Southern California (USC) and has consulted with the exercise industry on various topics, including vibration.
1) Adams, JB, Edwards, D, Serviette, D et al. Optimal frequency, displacement, duration, and recovery patterns to maximize power output following acute whole body vibration. J Strength Cond Res (23) (1): 237-45, 2009.
2) Cardinale, M and C Bosco. The use of vibration as an exercise intervention. Exer. Sport Sci Rev (31) (1): 3-7, 2003.
3) Delecluse, C, Roelants, M, and SM Vershueren. Strength increase after whole body vibration compared with resistance training. Med Sci Sports Exerc. (35) (6):1033-1041, 2003.
4) Donaldson, C and A Ross. Whole body vibration – useful or useless for athletes. Power Point.
5) Lowell, R, Midgley, A., Barrett S, et al. Effects of different half-time strategies on second half soccer-specific speed, power, and dynamic strength. Scand J Med Sci Sports:1-9, 2011.
6) Marin, PJ, Herrero, AJ, Sainz, N et al. Effects of different magnitudes of whole body vibration on arm muscular performance. J Strength Cond Res (24) (9):2506-2511, 2010.
7) Rauch, F, Sievanen, H, Boonen, S, et al. Reporting whole-body vibration intervention studies: Recommendations of the International Society of Musculoskeletal and Neuronal Interactions. J Musculoskelet. Neuronal Interact (10) (3):193-198, 2010.
8) Roelants, M, Delecluse, C, and SM Vershueren. Whole body – vibration training increases knee -extension strength and speed of movement in older women. Journal of the American Geriatric Society (52):901-908, 2004.
9) Varley, M, Fairweather, I, and R Aughey. Validity and reliability of GPS for measuring instantaneous velocity during acceleration, deceleration, and constant motion. Journal of Sport Sciences (30) (2):121-127, 2012.