What is the real cause of cramp?
Dr. Ross Tucker answers:
Well, a few specific questions can help identify causes.
Two questions to ask: Where are you most likely to cramp, and when? The answer is in the muscles you are using most (in running, the hamstrings, quads and calves); and as for the when, cramping happens during races, towards the end of the event, and is more likely to happen on challenging, hilly courses.
There is also the recent finding that runners who cramp are those who are over-extending themselves relative to their training. Runners were asked to predict their performance for an upcoming race based on their training, and the likely crampers turned out to be the ones who went off too hard, racing faster than their training suggested. That leads to muscle fatigue, and happens more on challenging courses – and only in the exercised muscles.
The simple answer, then, is fatigue. At a complex level, cramping is the result of a ‘malfunction’ of sorts in the neural control of the muscle – the nerves controlling the muscle fire inappropriately, and the result is a painful muscle spasm when the muscle should be relaxing.
Strength and pacing discipline. Strengthening delays and prevents fatigue, keeping the cramp at bay. This includes training for the race situation.
Then, pacing is crucial – don’t ask more of your muscles than you’ve prepared them for.
Dr Ross Tucker has a BSc (Med) (Hons) Exercise Science Degree and PhD from the Sports Science Institute. Visit him at