Cramps

Cramps are spasmodic, painful, involuntary muscle contractions. This page is focused on Exercise Associated Muscle Cramps (EAMC), though there are other types. Many runners suffer from cramps, and sometimes cramps can be severe enough to prevent the completion of an event, or catastrophically impact performance. What causes cramps and how can they be prevented? Sadly, no one seems to know, but here is what I’ve found out.

1 Hydration and Electrolytes

Conventional wisdom is that dehydration and/or electrolyte depletion causes cramping. The science does not back up this idea. A study of the 2000 South Africa Ironman Triathlon showed no correlation with dehydration or electrolyte levels with cramping. A study in 2005 showed that a carbohydrate/electrolyte drink delayed cramps in athletes that have a history of cramping. However the study had a small sample size of 13, and 7 cramped with the drink, 9 without the drink.

2 Altered Neuromuscular Control & Stretching

There is some support for the idea that cramps are neurological in origin. Altered neuromuscular control means that there is a disruption of the nervous control of the muscle, rather than a problem purely with the muscle itself. There is some evidence that muscles that are cramping have a higher level of electromyographic (EMG) activity and that a return of the EMG level to baseline correlates to recovery. The level of EMG is also reduced by static stretching, which has lead to an interesting theory. This theory is based on the idea that a cramping muscle loses its inverse stretch reflex. This inverse stretch reflex is stimulated by a prolonged stretch and causes the muscle to relax. If a muscle’s inverse stretch reflex becomes weakened, it will tend to contract strongly. The theory also explains why cramps are more likely to occur in muscles that are contracting in a shortened position (calf, hamstring). This theory suggests that stretching will help with cramping, not because of increased flexibility, but because it will reinforce the inverse stretch reflex. This theory also suggests to me that runners whose muscles are not fully extending while running may be more prone to cramping, but I have seen no mention of this elsewhere.

3 Exercise Level

Cramps are more common in runners who go further or faster than they are accustomed to. There is a belief that cramping is related to exhaustion of the cramping muscle, rather than overall fatigue. Higher levels of training may help prevent cramping.

4 Heat

It has been widely noted that cramping is more common in hot conditions. While this does not directly offer a way of preventing cramping, it is possible that Heat Acclimation Training may help.

5 Hypokalemia

There does appear to be a link between Hypokalemia (low potassium) and cramping, but is actually very unusual without medication or a serious medical condition such as kidney problems or AIDS.

6 Recommendations

There are no solid recommendations I can make, but here are some suggestions that may help.

• Stretch regularly using static stretching
• Perform Heat Acclimation Training for races that may be warm
• Stay hydrated; it won’t help with the cramping, but it’s still important! Practical Hydration