The Truth Behind Muscle Cramps

Truth by: Nick Youngson CC BY-SA 3.0 Alpha Stock Images

Much of what is commonly understood about muscle cramps today is from studies conducted during the early 1900’s. These researchers (Edsall and Moss) attributed muscle cramping to heat exposure and chloride loss via sweating. To this day, these variables are still regarded as culprits to muscle cramping during exercise. The term “salty sweateris commonly tossed around in the athletic training field as someone who is more susceptible to muscle cramping (Miller, 2018).

Later into the 20th century, Ladell’s research involved sodium chloride injections for subjects with muscle cramping. He noted that the cramps would dissipate after the intravenous sodium chloride was administered. Moss’ research on Hoover Dam workers showed that cramping could be associated with low blood chloride levels. With Ladell’s and Moss’ findings concurring with what researchers had previously discovered, the collective thoughts on muscle cramping were that it is caused by hard labor in hot conditions and imbalances of salt levels in the muscle tissue. This became known as the dehydration and electrolyte imbalance theory to muscle cramping.

Now, let’s fast forward to the 1990s. Vanilla Ice just released Ice Ice Baby, and regular unleaded was $1.15/gal. What a time to be alive. It was also a new era of understanding for muscle cramps due to research done by the aptly named Schwellnus (not kidding, that’s the real name). Schwellnus’ group discovered that low blood chloride levels and a heavy rate of sweating were not associated with athletes with a history of muscle cramps. Even when athletes replenished fluids that matched what was lost from sweat, cramps still occurred 70% of the time. Additionally, once cramping started, an increase in the athlete’s susceptibility to more cramping was observed for up to one hour, even when no fluid was lost from sweating. Furthermore, what provides immediate relief to acute muscle cramps is static stretching, and this technique does not alter the fluid levels or blood chloride levels in the body (Miller, 2018).

So what gives? What are the hypotheses of the Ice Ice Baby era of muscle cramping research that we should be subscribing to? Should we still be suggesting that frequent crampers drink some water and eat a banana? The modern research findings suggest otherwise. With Schwellnus’ findings, we can now ascribe to the altered neuromuscular theory. In other words, it is because of fatigue-induced changes to neuromuscular control that causes muscle cramps. So muscle cramps are more likely a nervous system issue, not a fluid level issue. In the lower brain centers and spinal cord are alpha motor neurons that innervate the muscle fibers. These neurons are firing off signals to the skeletal muscle to do the work you want to do; whether it’s curling dumbbells or pressing a brake pedal, your alpha motor neurons are responsible for muscle contraction (Miller, 2018).

If you frequently get muscle cramps, then you may benefit from types of training that rely on your alpha motor neurons. For example, fitness skills such as agility, coordination, and balance are dependent on neuromuscular control. Performing exercises that target these skills can effectively prevent muscle cramps. It’s possible that risk factors for muscle cramps can vary within a given individual, so identifying your unique risks is paramount to finding the appropriate remedy.

About the Author:

Sam Skelton is an ACSM Certified Exercise Physiologist, a proud husband, and a father to two young and rowdy boys. He enjoys surfing, guitar, and date nights with his wife. While he does not suffer from muscle cramps, his young boys do plenty to cramp his style. Check out Sam’s core strengthening series on [grokker.com] Grokker.

References:

Edsall, D. (1904). Two cases of violent but transitory myokymia and mytonia apparently due to excessive hot weather. Accessed via https://search.proquest.com/openview/3fb4d59fbddfed3f6a1c5ccd6e7a44d8/1?pq-origsite=gscholar&cbl=41361

Miller, K. (2018). The Evolution of Exercise-Associated Muscle Cramp Research. ACSMceOnline.

Moss, K. (1923). Some effects of high air temperatures and muscle exertion upon colliers. Accessed via https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.1923.0031

Schwellnuss et al. (1997). Aetiology of skeletal muscle cramps during exercise: a novel hypothesis. Accessed via https://www.researchgate.net/publication/13986241_Aetiology_of_skeletal_muscle_’cramps’_during_exercise_A_novel_hypothesis

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