Muscle cramps during exercise can drastically affect performance and are a common problem amongst endurance athletes. These cramps are common during or after exercise and can range from a minor cramp in a small muscle that passes quickly on its own, to a very painful cramp in a large muscle that remains causing pain for hours. The causes of cramps are not fully understood, but there are a few of causes that have been identified (see ‘What causes muscle cramps in exercise?’).
One of the suggested causes of muscle cramps is electrolyte imbalance. This would occur as a result of mostly sodium losses in sweat. There is no question that electrolytes are needed for normal function of muscles and are used in the process of contraction and relaxation of muscles. Therefore, it is tempting to think that depleting these electrolytes could result in disrupted and uncontrolled muscle contraction (i.e. cramping). Having said that it is surprising that we have extremely limited evidence that this is actually the case and the only studies that are always referred to are very old studies in mineworkers who worked long days in very hot mines.
We have extremely limited evidence that depleting electrolytes could result in disrupted and uncontrolled muscle contraction (i.e. cramping)
Nevertheless, the risk of cramping may be reduced by maintaining a good electrolyte balance, which can be achieved through consuming electrolytes during exercise (most notably sodium). Trying to match the amount of electrolytes lost in sweat with the amount ingested is not necessary, but avoiding large losses at the end of exercise is recommended. What very large is, is not exactly known but a loss of 5 grams of sodium is unlikely to be a problem and this is a very large loss.
Training specificity will be crucial in the prevention of muscle cramps
Electrolyte imbalances are probably only explaining a small percentage of cases of muscle cramping. Poor conditioning of the muscle is far more important. Training specificity will be crucial in the prevention, both in terms of exercise duration and intensity. Because competition is usually just a little more intense and just a little more effort than the hardest training sessions, cramps are more likely to occur in this situation. Also, changing position on a bike, for example, may change recruitment patterns and will engage previously "less trained" muscles. This can increase the risk of cramps, at least anecdotally.
Reducing exercise intensity
Once a muscle has started to cramp, there are few things that can be done to treat it. Many cramps will resolve themselves, lasting just a few seconds or perhaps minutes. If they occur during exercise, then allowing the muscle to relax by resting or reducing your speed for a short time while the cramp fades may be sufficient for minor cramps. If the cramp is in a muscle not being used (e.g. a cramp in the arm while running), then you may not even need to slow down to wait for this to resolve itself.
If cramps occur during exercise, then allowing the muscle to relax by resting or reducing your speed for a short time while the cramp fades may be sufficient for minor cramps
Of course, many cramps are too painful to simply ignore or may last for too long to simply stop and wait to resolve. Stretching is often suggested as the best way to resolve a cramp, which is supported by some case studies as well as anecdote. Stretching of the muscle activates a part of the muscle known as the ‘golgi tendon organ’. Activating the golgi tendon organ signals the nerve that controls the contraction of the muscle to reduce contraction, which should reduce the intensity of a cramp. However, the research into stretching to resolve muscle cramps is less supportive.
Therefore, although the evidence is not very strong for stretching, it is one of the few tools in the arsenal to treat a painful or long-lasting cramp.
Studying muscle cramps is difficult, because they are unpredictable and hard to trigger. Cramps can be triggered in the laboratory using electrical stimulation, and two studies failed to show that stretching could treat cramps caused by this stimulation. However, it is not clear that these contractions are functionally the same as the contractions that occur during exercise. Some very small studies and case studies have effectively used stretching to treat muscle cramps around exercise, but because so many cramps resolve themselves quickly on their own, it is not possible to be certain that the stretching helped resolve them. Therefore, although the evidence is not very strong for stretching, it is one of the few tools in the arsenal to treat a painful or long-lasting cramp.
A number of different foods and drinks have been suggested to be helpful in treating cramps, despite very limited evidence, including homeopathic and folk remedies, which speaks to the power of the placebo effect. Interestingly, drinking a tiny amount of pickle juice has been shown to reduce the length of muscle cramps by around ⅓. Although pickle juice contains sodium, it did not affect electrolyte balance. It was suggested that its high acetic acid content (and the sharp, unpleasant taste) might have activated nerves in the mouth that triggered the brain to slow down the contraction of the cramping muscle. This study was small and imperfectly designed, so pickle juice should not be used for treating cramps. However, it does suggest that there may be future avenues for treating cramps in interesting, non-traditional ways.
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