What Causes Cramps?

For a long time, the theory was that it was a shortage of magnesium or other electrolytes, and taking supplements would prevent cramp. However, research carried out in the last 10 years, including at the Two Oceans marathon, has shown that crampers do not have lower electrolyte levels than non-crampers, so there is no reason why taking electrolytes should help. Instead, recent work by researchers from the University of Cape Town at the Iron Man triathlon has hinted at another possible cause. Drs Martin Schwellnus and Malcolm found that athletes who were ambitious and set performance goals that were beyond their capabilities were far more likely to cramp than athletes who set realistic goals. It seems that cramps may be brought on by fatigue as a result of over-exertion, relative to training. The theory, according to Schwellnus, is that the neural control of the muscle is adversely affected by fatigue, causing the muscle to go into spasm, or cramp. So what should you do? Stretch the muscle immediately. This removes symptoms and it lowers the electrical activity in the muscle, showing that it actually relaxes the muscle.

Runner Dr Ross Tucker has a BSc (Med) (Hons) Exercise Science Degree and PhD from the Sport Science Institute of Cape Town and works closely with “running professor” Tim Noakes