Contrary to what we’ve been led to believe, no one knows what causes muscle cramps. The common lore is that the culprit is electrolytes, but this is highly doubtful. Much of the sports nutrition industry, however, is based on this myth. The first product I recall ever seeing that strongly promoted the myth was called E.R.G. (Electrolyte Replacement with Glucose). I sold it in my running store back in the early 1980s (Foot of the Rockies in Fort Collins, Colo.). It was a powder that came in a tear-open container which you mixed with water and drank before and during the competition.
Others companies with similar products have taken up the electrolyte battle cry in the last 30 years. A boatload of money is spent by these companies to keep us convinced that we must take in sodium, chloride, magnesium, potassium and/or calcium during exercise or run the risk of cramping. Dehydration has also been linked to muscles knotting up during exercise. So sports-drink companies, especially, have had a field day with cramping. They’ve done a great job of convincing us with nothing to show as proof other than myth. In fact, there have been a number of studies over the past quarter century showing that electrolytes and dehydration are not the cause [1,2,3,4,5,6]. But the myth refuses to go away.
So why do athletes continue to believe that cramps are caused by low electrolyte concentrations? Part of the answer is that the myth has a long history. Around the start of the 20th century dock workers were known to experience cramps while loading and unloading ships. Scientists back then took a look at the sweat of the workers who cramped and found chloride, which makes up about half of the salt in sweat. Without testing the sweat of the workers who did not cramp, they jumped to the conclusion that cramping was related to electrolyte loss and that heat and humidity were also involved. The myth was born.
It has been perpetuated over the decades by athletes who swear that when they take in electrolytes they don’t cramp. Or the opposite: When they don’t have access to sodium (or whatever) they do cramp. Sport is replete with such individual mythology. Athletes have their lucky coin, a spit before stepping into the batter’s box, a pair of socks worn when they’ve won or a mantra they must recite before the race begins. I once read about a famous American distance runner of the 1980s who had a lucky singlet and so wore it in every race – with great success. But when chosen to be on the U.S.A. team for international competition he had to wear the team uniform. His solution was to get a hotel room with a window that overlooked the race course and hang the lucky singlet in the window to ‘watch’ the race. I don’t recall how he did.
And there's more… I discovered about 10 years ago, after a great deal of research with n=1, that putting on my left shoe first is necessary to having a good race or workout. I’ve known this for a long time (and now you know it, too). To this day I always put my left shoe on first. And it’s worked. I have proof. Now it may not work for you, but it sure does for me.
Maybe putting on the left shoe and taking in electrolytes really does work. There’s this thing called the ‘placebo effect,’ which I’m sure you’re aware of so I won’t go into a discussion of it here. (If you’d like to know more about the placebo effect go here.)
So if it’s not a low electrolyte concentration or dehydration that causes muscles to cramp, what is the cause? Well, as mentioned at the start, no one really knows. There are theories. I’ll get into these in an upcoming post.
1. Brouns, F., E. Beckers, A.J. Wagenmakers and W.H. Saris. 1990. Ammonia accumulation during highly intensive long-lasting cycling: Individual observations. Int J Sports Med 11(S2): 278-84.
2. Maughan, R.J. 1986. Exercise-induced muscle cramp: A prospective biochemical study in marathon runners. J Sports Sciences 4(1): 31-34.
3. Miles, M.P. and P.M. Clarkson. 1994. Exercise-induced muscle pain, soreness, and cramps. J Sports Med Phys Fitness 34(3): 203-216.
4. Miller, K.C., G.W. Mack, K.L. Knight, J.T. Hopkins, D.O. Draper, P.J. Fields and I. Hunter. 2010. Three percent hypohydration does not affect the threshold frequency of electrically-induced cramps. Med Sci Sports Exerc March 2010 [epub ahead of print].
5. Schwellnus, M.P., J. Nicol, R. Laubscher and T.D. Noakes. 2004. Serum electrolyte concentrations and hydration status are not associated with exercise associate muscle cramping (EAMC) in distance runners. Brit J Sports Med 38(4): 488-92.
6. Sulzer, N.U., M.P. Schwellnus and T.D. Noakes. 2005. Serum electrolytes in Ironman triathletes with exercise-associated muscle cramping. Med Sci Sports Exerc 37(7): 1081-85.