Cramping was once thought to be caused by dehydration or electrolyte depletion, according to experts. However, no studies have been conducted to link the assumption that dehydration or electrolyte depletion is the reason one athlete cramps while another does not. There isn’t enough experimental evidence to support either theory. Researchers from the University of Cape Town examined 209 Ironman triathletes before and after a race in 2011 to see whether there were any differences between the 43 who suffered muscular cramps and the 166 who did not (1).
The main conclusion was that there was no significant difference in dehydration or electrolyte loss between the two groups, calling into question the commonly held electrolyte-depletion hypothesis of cramps.
The same research team examined serum electrolyte levels in Ironman South Africa athletes, and while the fall in sodium concentrations was significant, the difference compared to a control group was within the normal clinical range of post-race serum sodium concentrations (2). They were unable to link a drop in sodium concentration to an increase in exercise-induced muscular cramps. “Acute EAMC in ironman triathletes is not related with a larger % body mass loss or clinically relevant variations in serum electrolyte concentrations,” they concluded. Cramping muscles’ higher EMG activity may imply increased neuromuscular activation.”
Later that year, Schwellnus and his colleagues published a study in the British Journal of Sports Medicine that looked at 49 runners in the 56K Two Oceans Marathon in Cape Town (3). Those who cramped were more likely to have started too fast for their fitness level and to have trained more in the final week before competition, leaving their muscles weary.
The hypothesis of “altered neuromuscular control” is now being studied by researchers, who attribute much of the blame for muscle cramps to factors such as training, recovery, and pacing, as well as genetic vulnerability. In other words, muscle exhaustion causes aberrant functioning of the muscle contraction mechanism at the spinal level.
Here are some methods for preventing cramps:
* Prepare for the conditions (pace, terrain, temperatures, duration, etc.) in which you intend to compete
* Maintain a regular stretching programme
* Work on correcting any muscle imbalances or incorrect movement patterns; develop an efficient technique required for your sport
* Consume enough carbohydrates before, during, and after events lasting more than 2 hours; the amount will vary between individuals, but aim for 250 – 400 calories per hour during the event
If you have a cramp, do these things:
* Slow down and reduce the intensity of your activity
* Stretch and try to relax the afflicted muscle(s)
* Apply pressure to the affected muscle group(s) to get the muscles to “release”
References
- Schwellnus MP, Drew N, Collins M (2011) Increased running speed and previous cramps rather than dehydration or serum sodium changes predict exercise-associated muscle cramping: a prospective cohort study in 210 Ironman triathletes. Br J Sports Med. 2011 Jun;45(8):650-6. doi: 10.1136/bjsm.2010.078535. Epub 2010 Dec 9.
- Sulzer NU, Schwellnus MP, Noakes TD. Serum electrolytes in Ironman triathletes with exercise-associated muscle cramping. Med Sci Sports Exerc. 2005 Jul, 37(7):1081-5.
- Schwellnus MP, Allie S, Derman W, Collins M (2011) Increased running speed and pre-race muscle damage as risk factors for exercise-associated muscle cramps in a 56 km ultra-marathon: a prospective cohort study. Br J Sports Med. Nov;45(14):1132-6. doi: 10.1136/bjsm.2010.082677. Epub 2011 Mar 13.