Wednesday, 16 October 2013

'The drugs don't work': And neither do sports suppliments

A paper published last year in the BMJ carefully considered the evidence underpinning sports performance products. It concluded:

'The current evidence is not of sufficient quality to inform the public about the benefits and harms of sports products. There is a need to improve the quality and reporting of research, a move towards using systematic review evidence to inform decisions.'

Despite this, health and fitness magazines continue to proclaim that I and others should embrace supplementation. These adverts are particularly prevalent for whey protein and creatine.* Creatine is a naturally occurring substance that helps supply energy to all cells in the body. Of course, oxygen is also a naturally occurring substance that helps supply energy to all cells in the body, but it doesn't mean I carry an oxygen tank while running.

Not yet anyway.




A typical sports supplement. The word 'PhD'  gives an air of scientific merit. There is none. 


There remain colossal problems behind research involving the use and effectiveness of creatine and other supplements. Companies such as PhD above annoy the hell out of me because they are able to sell something that almost certainly doesn't work**.

General problems across peer-reviewed literature assessing the effectiveness of these supplements include:
  • An overemphasis on male athletes instead of 'average people' who take exercise on a regular basis. 
  • Group sizes that are almost always in single figures and often unbalanced across conditions. Healthy men and women are not a special population so there is no reason I can find to have such a small sample size.  
  • There is therefore a high chance of false positives (i.e. finding a significant effect when there isn't one). 
  • A lack of randomised controlled trials. There is often no true control group and only a placebo.
  • Inappropriate use of parametric statistics given the reported sample sizes and large standard deviations.
  • Little/no control for changes in diet or the amount of exercise taken across a testing period.
  • Little/no control for participants taking other legal or illegal supplements (e.g.. Steroids) 

A growing number of studies are now failing to support the notion that creatine for example, has any beneficial effect on fitness or strength (e.g. Balsom, Harridge, Soderlund, Sjodin & Ekbolm 2008; Rahimi et al 2011). A meta-analysis from 2003 found a very small effect, but this seems a little out of date in light of new evidence.

Economics

The power of advertising makes people forget that they are probably paying for something that looks pretty, but does nothing. Take Maximusle for example. You're meant to start off with a loading dose of 33 grams four times a day. After the first week this drops down to a maintenance dose of 33 grams twice a day. This would cost £960 a year***.

Personally, I would take that money and hire a personal trainer for one hour a week and incorporate those sessions into part of regular exercise programme. Prices vary, but £15 an hour is typical. Fifty-two hours would cost £780 a year.

In saying that I don't suppose the evidence base for hiring a personal trainer is particularity great either, but something tells me that any behavioural intervention has got to be better than an over-priced and over-marketed alternative.



*I appreciate that these magazines are predominately funded by advertising. However, I am more likely to pay more for a publication that wasn't full of s**t.

**See the Sale of Goods Act 1979.

***A 1.1Kg tub (33 servings) costs £48

Weekly Servings
First week = 4*7 = 28 servings
Maintenance week = 14 servings

Monthly Servings
Total servings in first month = 28 + (14*3) = 28 + 42 = 70
Total servings in a regular month thereafter = 28 days * 2 servings a day = 56

Yearly Servings
Total servings in a year = 70 + (56*11) =70 +616= 686

Purchases Required
686/33 = 20 1.1Kg tubs required

Total cost for one year = 20 *48

£960


References

Balsom, P. D., Harridge, S. D. R., Soderlund, K., Sjodin, B. and Ekbolm, B. (2008). Creatine supplementation per se does not enhance exercise performance. Acta Physiologica Scandinavica. 149(4), 521-523.

Branch, J. D. (2003). Effect of creatine supplementation on body composition and performance: a meta-analysis. International Journal of Sport Nutrition and Exercise Metabolism. 13(2), 198-226.

Murphy, A. J., Watsford, M. L., Coutts, A. J.and Richards, D. A. B. (2005). Effects of creatine supplementation on aerobic power and cardiovascular structure and function. Journal of Science and Medicine in Sport. 8 (3), 305-313.

Rahimi, M., Kordi, M., Karimi, N., Gaeini, A., Samadi, A. and Moradi, N. A. (2011). The effects of whole body vibration training on creatine supplementation on lower extremity performance and balance in elderly males. Iranian Journal of Aging. 6(19).

Sterkowicz, S., Tyka, A. K., Chwastowski, M., Sterkowicz-Przybycie┼ä, K., Tyka, A.and Klys, A. (2012). The effects of training and creatine malate supplementation during preparation period on physical capacity and special fitness in judo contestants. Journal of The International Society of Sports Nutrition. 9 (41). 1-8.