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What Causes Muscle Cramps?

If you have ever had a muscle cramp, you know the little evil contained in each little spasm. It can take you from cruising along to huddled on the ground questioning your very existence. But why do muscle cramps happen and what should we do to fix or prevent them?

We have all heard the advice for curing cramps:

- Eat a banana every day

- Drink pickle juice

- Don’t start out too fast – slow down

- Your electrolytes are too low – drink a gatorade

- You got overheated – stay cool

You may have even tried some of these remedies with varying degrees of success! I’m sure there are plenty of other wild remedies for cramps that I haven’t even thought of or listed here.

What is a muscle cramp?

The prevailing theory behind muscle cramping is a breakdown of the neurological and chemical firing sequences. Basically, your muscle has a serious miscommunication with the nerve that leaves the “switch” stuck in the “on” position. When this happens, the muscle refuses to let go and can spasm and squeeze with a severe intensity.

What can we do about a muscle cramp when it is happening?

This is where the folktales come alive! Slamming a jar of pickle juice. Chugging a Gatorade. Having a friend stretch out your calf to make it relax. Eating 8 bananas as fast as you can. Massage the muscle vigorously. Take a gel pack. Take a specially formulated “cramp buster” supplement drink. The remedies vary and can have different rates of success per person, and we don’t really know which truly help everyone.

Why do cramps happen?

A study performed last year tried to assess the differences physiology among those runners who cramped in a road marathon. These researchers examined 88 marathoners and their levels of body weight change, urine concentration, sodium, and potassium levels. Among these 88 marathon finishers, 20 (24%) of them cramped during or right after the race.

If we want to believe the prevailing theory of electrolyte depletion as a cause of cramping, then we should see a significant difference between crampers and non-crampers for sodium and potassium levels. However, that was not the case. There were no differences between these two groups for electrolyte levels.

What about dehydration levels? Maybe they just lost enough water that they started to cramp? Well, the urine and body weight differences were non-existent as well. Both groups had similar changes.

Since these values didn’t reveal any clues, the researchers dove deeper. They examined creatine kinase and lactate dehydrogenase levels. These chemicals are markers of cellular damage. Interestingly enough, the cramping group had significantly higher levels of these chemicals versus the non-crampers. So, what do we make of this? Well, it appears that the crampers had some level of muscle damage that accompanied the cramps. Do we know if the damaged caused the cramps or the other way around? We do not. However, there is one more clue.

Between the crampers and non-crampers, there was nearly a significant difference between those who performed regular strength training and those who did not. Guess which group performed more strength trainig prior to the marathon? You guessed it. The non-crampers. They collectively had 47.6% of the group perform strengthening, while the cramping group only had 25% perform strength training. Now, admittedly, this is not a statistically significant difference. However, it does give us pause.

What should we do to avoid cramping?

It would appear that strength training may have a protective effect on cramping during a race. The statistics for electrolyte and dehydration where essentially the same between two groups, so it appears that this is not a primary cause for cramps.

Perhaps the cramps experienced were a result of extreme muscle fatigue, and even damage, which is why the markers for cellular damage were elevated in those who cramped. Perhaps the prior strength training the non-crampers did before the race protected them from extreme fatigue. Perhaps going out too fast and cramping has less to do with hydration and electrolytes and more to do with hitting your extreme fatigue point, sooner.

Anecdotally, I can tell you that in the clinic a simple rule applies. The weaker a person is, the more likely they are to cramp during an exercise. This is nearly a golden rule.

So, in summary, if you would like to avoid cramps, maybe we can put away the pickle juice and instead pick up the barbell. Your performance will thank you!

Thanks for reading,


Martínez-Navarro, I., Montoya-Vieco, A., Collado-Boira, E., Hernando, B., Panizo, N., & Hernando, C. (2020). Muscle cramping in the marathon: dehydration and electrolyte depletion vs. muscle damage.


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