A runner’s racing frequency and intensity often increases during the fall marathon and cross-country season. Unfortunately for many, a longer distance and greater effort can result in painful leg cramps. In every half marathon that I have ever run, I have experienced leg cramps during the final miles of the race. I would like to avoid them, so I started doing some research into the mysteries of leg cramps and their prevention. Most of the articles that I have read point to some common myths about the causes of leg cramps but it turns out that there’s been no conclusive evidence about the causes. There also doesn’t appear to be much scientific evidence on effective cures.
Before I discuss remedies, let me review the potential causes. The most commonly mentioned cause of leg cramps is dehydration. Muscles are 60% water; our assumption, confirmed in the popular press, simply take the connection between dehydration and cramping as a given. (For example, when football players experience severe leg cramps on the field, reports from the bench invariably stress that the cause is dehydration and announcers are quick to confirm the diagnosis.) Researchers have long known, however, that there is merely a correlation between dehydration and cramping. Bob Anderson and Joe Henderson’s 1975 classic, Guide to Distance Running, doesn’t even mention water loss as a harbinger of leg cramps. New York Times health reporter Gina Kolata called into question the relationship between dehydration and cramping in an article entitled, “A Long-Running Mystery, the Common Cramp.” (http://query.nytimes.com/gst/fullpage.html?res=9F00E2D7173BF937A25751C0A96E9C8B63) Kolata cited the expertise of Dr. Schwellnus, who studied cramping athletes and found that they were no more dehydrated before or after a race than those who did not have cramps.
This leads us to a consideration of the second major theory of running cramps –– the electrolyte hypothesis. This theory rests upon one of the earliest and commonly agreed upon reasons for cramping: sodium deficiency. The Guide to Distance Running recommended salt tablets as a cure, and provided a recommended intake schedule: it seemed like a lot of salt. Sodium deficiency, however, is still seen today as a problem. How does it work? According to Dr. Michael F. Bergeron, in “A Long-Running Mystery, the Common Cramp,” when the fluid that bathes the connection between muscle and nerve is depleted of sodium and potassium through sweat loss, the nerve becomes hypersensitive and cramping results. Bergeron’s description of the cramping process accurately describes how my leg cramps have always progressed: little twitches followed by full-blown cramps. His remedy? Drink salty fluids. A sports drink such as Gatorade or Powerade should suffice. If you want to avoid excessive sugar, while getting sodium and electrolytes, try NUUN. Despite the fact that there seems to be a consensus that sodium depletion leads to cramps, Dr. Bergeron had to admit that there were not any rigorous studies to confirm the electrolyte hypothesis. In fact, despite sounding like what many of us experience, a recent examination of Iron Man triathletes and other endurance athletes found no differences in electrolyte levels between those who experienced muscle cramps and those who didn’t.
If we can’t directly attribute leg cramps to dehydration or sodium deficiency, what is the next viable theory? It’s the fatigue theory. According to Dr. Schwellnus, cramping is caused by an imbalance between the nerve signals that excite a muscle and those that inhibit its contractions. The critical imbalance occurs when a muscle grows fatigued. His recommendation is to exercise less intensely and for shorter times and to regularly stretch the problematic muscles. Interestingly enough, the Guide to Distance Running also cites fatigue as a cause of leg cramps. Too much running at too high an intensity without adequate rest essentially makes one more susceptible to cramping in subsequent runs. The fatigue theory makes some sense for those of us who only experience cramping issues while racing. My own leg cramping emerged as I quickened the pace during races. I wondered whether my endurance had outstripped my muscular-skeletal capacity, thus resulting in the ability to overstress my body during racing. Obviously, we can’t really endorse Schwellnus’ recommendation to exercise less intensely, although we can get behind additional stretching and massage.
After having assessed the prevailing theories about what causes leg cramps during running, and finding convincing evidence that there is little agreement on causes, we are still left with the pragmatic consideration of what to do. I just read an article by Pete Williams, “Mustard: A Cure for Cramps?” (http://www.coreperformance.com/daily/nutrition/mustard-a-cure-for-cramps.html) in which he suggests eating one or two spoons of yellow mustard to prevent muscle cramps. The theory is that cramps can be caused by a deficiency in acetylcholine, the neurotransmitter that stimulates muscles to work, and mustard contains acetic acid, which helps the body produce more acetylcholine. Williams points out that it is possibly the vinegar common in both pickle juice (a traditional anti-cramping remedy) and mustard that stimulates the necessary neurotransmitter. There are, of course, no scientific studies on the connection between vinegar and cramp prevention, but the anecdotal evidence convinces Williams. He also suggests that ingesting mustard packets might merely be another way of getting additional sodium. So, if you aren’t having any luck with electrolyte replacement or increasing your sodium, pick up some mustard packets for your next race.
One of the questions that emerge from this discussion is “what about well-trained, professional athletes who experience debilitating cramping episodes?” In these cases, I would suspect that athletes doing a whole lot of mileage and speed work might be going into races with tired legs susceptible to muscle fatigue despite doing all the things necessary to build muscle strength and endurance. Thus, if you experience an isolated incident of cramping during a race, it might just mean that you did not adequately taper and that your leg muscles were still stressed from previous hard workouts. I think the key to avoiding leg cramps is to have the necessary muscle strength and endurance for your chosen race distance. This, of course, is not as straightforward as it sounds, because we are often striving to go faster and longer and it is difficult to be prepared for every distance and speed, especially if you have never before tackled a specific distance. My final piece of advice: don’t get freaked out if you experience leg cramps while exceeding the limits of your speed and endurance. It merely means that you are pushing your limits; but, luckily, with additional training you can successfully push back those limits. Cramps, therefore, might be a sign that you are on the way to getting faster, a painful indicator; but, ultimately, a positive sign of improvement.
Have you experienced leg cramps while running? Under what conditions did they occur? How did you deal with them? Do you have any sure-fire remedies? Tell us all about it in the comments.