New ideas behind muscle cramping

We can all relate to the football player who goes down on the field holding his calf as it cramps. The next step is always to try and stretch and loosen up the muscle. These painful contractions of the muscle usually subside in seconds to minutes but why do they occur? The mechanism behind the muscle cramping had been believed to be dehydration and lack of electrolytes until recently.

Newer research now suggests that the "cramp" contractions are associated with repetitive firing of the motor unit action potentials. This essentially equates to dysfunction in the nervous system and the electrical signals that the nerves send to the muscles to contract. As a muscle fatigues it changes the amount of electrical input needed to contract the muscle, which can possibly put the muscle at higher risk of cramping.

The main risk factors for exercise-associated muscle cramps include family history of cramping, previous occurrence of cramps during or after exercise, increased exercise intensity and duration, and inadequate conditioning for the activity. From a physical therapy perspective this demonstrates that we need to focus on proper training and strengthening of muscles and not necessarily as much on the diet when trying to prevent muscle cramping.

Lukas Mehling PT, DPT

Resources

Minetto, Marco Alessandro, et al. "Origin and development of muscle cramps." Exercise and sport sciences reviews 41.1 (2013): 3-10.

Miller, Kevin C. "Rethinking the cause of exercise-associated muscle cramping: moving beyond dehydration and electrolyte losses." Current Sports Medicine Reports 14.5 (2015): 353-354.

Mills, Stanley L. "Treating and inhibiting recurrence of muscle cramps." U.S. Patent Application No. 13/681,006.