If you run, it is likely that you have already felt that cramp in your calf or thigh in the middle of a long workout or the final stretch of a race. The immediate reaction of most runners is to think: “I should have eaten a banana.”
This is one of the oldest and most ingrained myths in sports. The truth is that exercise-associated muscle cramps (EAMC) rarely have anything to do with the lack of potassium from bananas. Eating a dozen bananas before the race will not save your calf if the foundation of your diet and your training are out of balance.
To say goodbye to this pain and run freely, we need to look at the true clinical causes of cramps on the asphalt.
The Potassium and Banana Myth
Why doesn’t the banana solve it? Cramping was traditionally seen only as a problem of dehydration and electrolyte loss through sweat. However, when we sweat, we lose mainly water and sodium. The loss of potassium through sweat is clinically insignificant.
The banana is an excellent fruit and a great source of energy for pre-workout, but using it as an anti-cramp “remedy” based on potassium is a physiological mistake. The real problem is usually much more related to what is missing from your plate than the lack of a specific fruit.
The Hidden Cause: Lack of Carbohydrates and an Unbalanced Diet
Here is the secret that few runners know: cramping is, in essence, a symptom of extreme fatigue. And nothing fatigues a muscle faster than a lack of fuel.
Your legs’ main source of energy during a run is glycogen (the carbohydrate stored in the muscles). If you have an unbalanced diet, low in carbohydrates, or are afraid to eat rice, bread, and pasta, you already start the run with an “empty tank”. As we detailed in our diet for beginner runners, carbohydrates are not the villain, they are your hero.
When the muscle runs out of energy, it cannot contract and relax efficiently. This energy failure alters the communication between nerves and muscle fibers. The nerve becomes “hyperactive” and fires commands non-stop, resulting in the strong and involuntary contraction that we call a cramp.
Therefore, before an important race, ensuring your energy stores with a good carbo-loading for long races is one of the best preventive strategies.
Neuromuscular Fatigue: Pace Over the Limit
In addition to the lack of carbohydrates, the other major cause of cramping is pushing a pace or a distance for which your muscles are not yet prepared. If you train to run 10km in 1 hour, but on race day you try to do it in 45 minutes, the muscle fatigues prematurely, and a cramp will be almost inevitable, no matter how good your nutrition is.
The Role of Sodium and Hydration
Although the electrolyte theory is not the only villain, the loss of sodium (not potassium) in sweat can be a problem, especially on hot days. Runners who sweat a lot and run long distances may need to replenish this mineral.
How to Actually Prevent It:
- Eat Carbohydrates: Ensure your muscle has energy so it doesn’t collapse. In workouts lasting more than 1 hour, replenish energy midway using the correct strategy of running carbohydrate gel.
- Train for the Distance: Respect the training volume on your spreadsheet.
- Drink Water with Sodium: On long workouts and hot days, plain water is not enough. Use sports drinks or replenish the minerals recommended by your sports dietitian.
Practical Verdict
Next time you get a cramp, don’t blame the poor banana. Review your training to see if you didn’t overdo the effort, and most importantly, analyze your diet. A muscle well-fed with carbohydrates, well-hydrated with water and sodium, and progressively trained is a cramp-proof muscle.
By Gabriel Bueno Bocchi, Registered Dietitian / Sports Nutritionist (University of Campinas – UNICAMP)