Something that every trainer or coach or somewhat-athletic person will always get asked is: “what causes my muscle cramps?”
That’s an excellent question.
For some reason, a hypothesis that has claimed the fame as the culprit for these little suckers is electrolyte imbalance in our bodies because of exercise. Well, you can put down your pickle juice because that actually hasn’t been consistently proven. Many studies have even come out with evidence that it is, in fact, not the cause at all (1),(3),(4).
This actually makes sense. If you look at evidence taken from marathon runners, their sweat electrolyte loss seems to have no relationship between fitness level or their blood concentrations before the race (2). The only small relationship was that men seem to lose more electrolytes than women.
So, that just leaves us wondering why we’ve been “rehydrating” with those sports drinks all these years.
Don’t fret yet – there’s this new idea floating around the science world lately. It’s a proposal called the “altered neuromuscular control hypothesis,” which basically states that cramps could be a mess-up in the messages from the brain to the muscles, which causes them to seize up. This
is referred to as “muscle misfiring.” A study released in 2013 (5) found that when the muscles are worked really hard, they tend to be more likely to suffer from cramps. The same study then brought up the idea that tiring the muscles will cause the misfiring of the brain messages, which is why so many people seem to get cramps during, or soon after, exercise.
Another study then went at it with a different angle: measuring the energy stores for high-intensity exercise, known as creatine kinase (which we’ll call CK). This study found that marathon runners who had larger stores of CK before their race were more likely to report cramps during the run or within one week following (6). Furthermore, sled dogs were recently reported in yet another experiment to have higher levels of CK in their muscles after 2 consecutive days of endurance racing (8).
Between the ideas of messed up brain messages and CK levels in the muscle, there seems to be a correlation: heavier exercise can lead to higher CK levels, and heavier exercise can lead to greater likelihood of misfiring muscles.
And since the reason for cramping still isn’t clear, we unfortunately don’t have any fixes for it at this time. However, one study has found that the pain threshold of cramp sufferers can be raised by electrically stimulating cramps once per week in the calf muscles (7). While the only goal of this experiment was to see if the scientists could get people to suffer less from their own cramps, something else actually happened. Those who received the electrically-stimulated cramps actually stopped CK levels from rising in their muscles.
So, final stance as of now: No definite cause of cramps has been determined. The only improvement in cramps with significant effect so far is to increase the sufferer’s pain threshold to them. And there is a likelihood that high CK levels may play a role in muscle misfiring in fatigued muscles.
This topic is huge in research right now, so the best answer we can give is to be patient as science does its thing. Unless, of course, you want to see if anyone is running more of those electronically-stimulated calf experiments. But that doesn’t sound too great to me…
About the Author
Allison is a certified personal trainer & owner of www.flabstofitness.com, which is a resource targeted at living a well-rounded healthy life. She is a full-time student at the University of Texas at Austin, finishing up her senior year with two degrees: a Bachelor’s of Science in Kinesiology, and Bachelor’s of Arts in Theatre & Dance. You can find her on social media under @flabstofitness, and most likely in person somewhere outside.
- Braulick, K.W., Miller, K.C., Albrecht, J.M., Tucker, J.M., Deal, J.E. (December 6, 2012). Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency. British Journal of Sports Medicine. doi: 10.1136/bjsports-2012-091501
- Lara, B., Gallo-Salazar, C., Puente, C., Areces, F., Salinero, J.J., Del Coso, J. (July 29, 2016). Interindividual variability in sweat electrolyte concentration in marathoners. Journal of the International Society of Sports Nutrition. doi: 10.1186/s12970-016-0141
- Murray, D., Miler, K.C., Edwards, J.E. (August 2016). Does a reduction in serum sodium concentration or serum potassium concentration increase the prevalence of exercise-associated muscle cramps? Journal of Sport Rehabilitation. doi: http://dx.doi.org/10.1123/jsr.2014-0293
- Harnish, C. (n.d.). Understanding exercise-induced muscle cramps. Active. Retrieved from http://www.active.com/fitness/articles/understanding-exercise-induced-muscle-cramps
- Minetto, M.A., Holobar, A., Botter, A., Farina, D. (January 2013). Origin and development of muscle cramps. Exercise and Sport Sciences Reviews. doi: 10.1097/JES.0b013e3182724817
- Hoffman, M.D., Stuempfle, K.J. (May 21, 2015). Muscle cramping during a 161-km ultramarathon: comparison of characteristics of those with and without cramping. Springer Open. Doi: 10.1186/s40798-015-0019-7
- Behringer, M., Link, T.W., Montag, J.C., McCourt, M.L., Mester, J. (September 28,
2015). Are electrically induced muscle cramps able to increase the cramp threshold frequency, when induced once a week? Orthopedic Reviews. doi: 10.4081/or.2015.6028
- Frank, L., Mann, S., Johnson, J., Levine, C., Downey, R., Griffits, C., Wakshlag, J. (August 31, 2015). Plasma chemistry before and after two consecutive days of racing in sled dogs: associations between muscle damage and electrolyte status. Comparative Exercise Phyhsiology. Doi: http://dx.doi.org/10.3920/CEP150020