Muscle cramps are a complicated issue. It’s easy to recognize when you have one, but so far it has proven extremely difficult to explain why, or where it came from. And it’s nearly impossible to predict when a cramp will strike, even for athletes who are prone to cramping. These inconsistencies make studies complicated to perform. In fact, it’s only been in the last 10-15 years that true breakthroughs in our understanding of cramps have occurred. Before that, researchers relied heavily on observations and incomplete, anecdotal evidence to formulate their theories. Unfortunately, this has lead to many well-established misconceptions that still exist today.
But, because cramps are complicated and misunderstood, it also requires a complicated explanation. In an effort to make this a less daunting task, we will break it up into several parts. Over the next few weeks, we will be exploring the most prevalent muscle cramp myths, and discover how they developed, the logic behind them, and what recent research suggests is actually true. This week we are investigating the dehydration myth.
But, because cramps are complicated and misunderstood, it also requires a complicated explanation. In an effort to make this a less daunting task, we will break it up into several parts. Over the next few weeks, we will be exploring the most prevalent muscle cramp myths, and discover how they developed, the logic behind them, and what recent research suggests is actually true. This week we are investigating the dehydration myth.
Part 1: Dehydration Does Not Cause Cramping!
Three of the most visited health websites in the US, WebMD, EveryDay Health, and Active list dehydration as a cause or factor in muscle cramps. The basic theory is that, as your body loses water (and electrolytes - see Myth #2 next week), your muscles become depleted of the nutrients they need to properly function. This makes them hypersensitive and susceptible to involuntary contractions and spasms. It seems to make sense. After all, water is essential for physiological function, and logic suggests that less water in your body would cause problems for your muscles.
Even elite athletes, who work with some of the best trainers, coaches, and medical staff in the world, often attribute their own cramps to dehydration. After Game 1 of the 2014 NBA Finals, in which LeBron James famously cramped and had to be physically carried off the court, he told ESPN, “I was losing [a lot] of fluids throughout the game. It was extremely hot in the building, you know, both teams, fans, everybody could feel it.”
However, study after study has shown that dehydration is likely not the cause. In 2004, Dr. Martin Schwellnus, a professor at the University of Cape Town, performed a study on runners participating in the Two Oceans marathon. After the race, the “crampers” and “non-crampers” were matched based on body mass and finishing times, and several variables were tested. The results showed that the runners who cramped lost 2.9% of their body weight on average (a rough measure of dehydration), while the non-crampers lost an average of 3.6%. Put another way, the runners who lost the most weight during the race, DID NOT cramp.
The researchers also measured the participants’ plasma levels, which is a more direct representation of hydration. The crampers had a slight increase of 0.2%, on average, while the non-crampers lost an average of 0.7%. Again, this goes against the idea that dehydration is playing a significant role. Both of these tests indicate that the cramp group was actually MORE HYDRATED than the non-cramp group.
In 2010, researchers at North Dakota State University performed a clever study to test the dehydration hypothesis. Because this was performed in a lab, rather than in the field, as Dr. Schwellnus’ study was, more variables can be controlled, and thus it is a bit easier to draw conclusions. Researchers asked participants to pedal a stationary bicycle, using only their non-dominant leg, until they lost about 3% of their initial body weight (greater than 3% is considered “significant” dehydration, while greater than 5% is “serious”).
Muscle cramps were artificially induced in the subjects’ legs, both before and after dehydration set in. In other words, the experimenters tested the leg that had done all the work, as well as the leg that had not exercised at all. Based on the results, the researchers concluded that, “Mild hypohydration with minimal neuromuscular fatigue does not seem to predispose individuals to cramping. Thus, cramps may be more associated with neuromuscular fatigue than dehydration/electrolyte losses.” The North Dakota State team did caution, however, that the effects of greater fluid loss on muscle cramping should be explored.
Well, in a 2013 study published in the British Journal of Sports Medicine, researchers did exactly that. 10 participants repeated a similar procedure to that of the ND State study, but this time they continued exercising until they reached an average body weight reduction of 4.7%. Again, the researchers concluded that dehydration did not increase the risk of muscle cramps. Instead, “neuromuscular control” (which we will get into more in the coming weeks) is a more likely hypothesis.
Three of the most visited health websites in the US, WebMD, EveryDay Health, and Active list dehydration as a cause or factor in muscle cramps. The basic theory is that, as your body loses water (and electrolytes - see Myth #2 next week), your muscles become depleted of the nutrients they need to properly function. This makes them hypersensitive and susceptible to involuntary contractions and spasms. It seems to make sense. After all, water is essential for physiological function, and logic suggests that less water in your body would cause problems for your muscles.
Even elite athletes, who work with some of the best trainers, coaches, and medical staff in the world, often attribute their own cramps to dehydration. After Game 1 of the 2014 NBA Finals, in which LeBron James famously cramped and had to be physically carried off the court, he told ESPN, “I was losing [a lot] of fluids throughout the game. It was extremely hot in the building, you know, both teams, fans, everybody could feel it.”
However, study after study has shown that dehydration is likely not the cause. In 2004, Dr. Martin Schwellnus, a professor at the University of Cape Town, performed a study on runners participating in the Two Oceans marathon. After the race, the “crampers” and “non-crampers” were matched based on body mass and finishing times, and several variables were tested. The results showed that the runners who cramped lost 2.9% of their body weight on average (a rough measure of dehydration), while the non-crampers lost an average of 3.6%. Put another way, the runners who lost the most weight during the race, DID NOT cramp.
The researchers also measured the participants’ plasma levels, which is a more direct representation of hydration. The crampers had a slight increase of 0.2%, on average, while the non-crampers lost an average of 0.7%. Again, this goes against the idea that dehydration is playing a significant role. Both of these tests indicate that the cramp group was actually MORE HYDRATED than the non-cramp group.
In 2010, researchers at North Dakota State University performed a clever study to test the dehydration hypothesis. Because this was performed in a lab, rather than in the field, as Dr. Schwellnus’ study was, more variables can be controlled, and thus it is a bit easier to draw conclusions. Researchers asked participants to pedal a stationary bicycle, using only their non-dominant leg, until they lost about 3% of their initial body weight (greater than 3% is considered “significant” dehydration, while greater than 5% is “serious”).
Muscle cramps were artificially induced in the subjects’ legs, both before and after dehydration set in. In other words, the experimenters tested the leg that had done all the work, as well as the leg that had not exercised at all. Based on the results, the researchers concluded that, “Mild hypohydration with minimal neuromuscular fatigue does not seem to predispose individuals to cramping. Thus, cramps may be more associated with neuromuscular fatigue than dehydration/electrolyte losses.” The North Dakota State team did caution, however, that the effects of greater fluid loss on muscle cramping should be explored.
Well, in a 2013 study published in the British Journal of Sports Medicine, researchers did exactly that. 10 participants repeated a similar procedure to that of the ND State study, but this time they continued exercising until they reached an average body weight reduction of 4.7%. Again, the researchers concluded that dehydration did not increase the risk of muscle cramps. Instead, “neuromuscular control” (which we will get into more in the coming weeks) is a more likely hypothesis.
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