We’ve all had it happen. The workout is going great – then all of a sudden, from out of nowhere, a muscle begins to feel “twitchy” and seizes up. You slow down, hoping it will go away. It does, but as soon as you start pouring on the power, it comes back. The promise of a stellar workout is gone.


Muscles seem to knot up at the worst possible times – seldom in training, but frequently in workouts. The real problem is that no one knows what causes cramps. There are theories, the most popular being that muscle cramps result from dehydration or electrolyte imbalances. These arguments seem to make sense – at least on the surface. Cramps are most common in the heat of summer, when low body-fluid levels and decreases in body salt due to sweating are likely to occur.


But the research doesn’t always support these explanations. For example, in the mid 1980’s, 82 male runners were testes before and after a marathon for certain blood parameters considered to be likely causes of muscle cramps. Fifteen of the runners experienced cramps after 18 miles. There was no difference, either before or after the race, in blood levels of sodium, potassium, bicarbonate, hemoglobin, or hematocrit. There was also no difference in blood volume between the crampers and non crampers, nor were there significant differences in the way the two groups trained.

Note that we are talking about exercise induced cramps here. In such cases of cramping, the knotted muscle is almost always one that is involved in movement in the sport. If depletion of electrolytes was a cause of cramping during exercise, why wouldn’t the entire body cramp up? Why just the working muscles? Electrolytes are lost throughout the body, not just in working muscles. We know that people who become clinically hyponatremic by losing a great deal of body salts (not exercise-induced) cramp in all of their muscles. It’s generalized, not localized.


It should also be pointed out that when someone cramps, the “fix” is not hurriedly drinking a solution of electrolytes, but rather stretching the offending muscle. For example, a runner with a calf cramp will stop and stretch the calf muscle by leaning against a wall or other object while dorsiflexing the ankle against resistance – the standard “runners stretch.”


In fact, what is known is that sweat, with regards to electrolytes, is hypotonic. That means the concentration of sodium, potassium, magnesium, chloride, and calcium is weaker than it is in the body. This indicates that more water is lost in the sweat than electrolytes. So if the body lost more of its stored water but not as much of its electrolytes, what would happen to electrolyte concentration in the body? The concentration should increase. So during exercise when you dehydrate and lose electrolytes, their concentration in the body is greater than it was before you started to exercise. The body functions based on concentrations, not on absolute amounts.  That alone presents a great problem for the argument that the cause of cramping is the loss of electrolytes that must be replaced.


So if dehydration or electrolyte loss through sweat doesn’t cause cramping, what does? No one knows for sure, but theories are emerging. Some researches blame poor posture or inefficient biomechanics. Poor movement patterns may cause a disturbance in the activity of the Golgi tendon organs – “strain gauges” built into the tendon to prevent muscle tears. When activated, the organs cause the threatened muscles to relax while stimulating the antagonistic muscle – the one that moves the joint in the opposite way – to fire.


There may be some quirk of body mechanics that upsets a Golgi device and sets off the cramping pattern. If that is the cause, prevention may involve improving biomechanics and regularly stretching and strengthening muscles that seem to cramp, along with stretching and strengthening the antagonistic muscles.

Another theory is that cramps result from the burning of protein for fuel in the absence of readily available carbohydrate. In fact, one study supports such a notion: Muscle cramps occurred in exercising subjects who reached the highest levels of ammonia release, indicating that protein was being used to fuel the muscles during exercise. This suggests a need for greater carbohydrate stores before, and replacement of those stores during, intense and long-lasting exercise.


When you feel a cramp coming on, there are two ways to deal with it. One is to reduce your intensity and slow down – not a popular option in an important workout. Another is to alternately stretch and relax the affected muscle group while continuing to move. This is difficult if not impossible to do in some sports and with certain muscles.

There is a third option some athletes swear by: pinching the upper lip – it may work for you the next time a cramp strikes.

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