Exercise-associated muscle cramping is one of the most common complaints among athletes, and the cause of these cramps is still under investigation.
Historically, it was thought that muscle cramping was the result of dehydration and electrolyte imbalance, and that consuming fluids and foods rich in electrolytes (sodium, chloride, potassium, magnesium and calcium) would help to prevent or treat cramps. However, current studies have not found significant differences in blood electrolytes, hydration status, or sweat sodium content between individuals experiencing this type of cramping compared with unaffected athletes. Instead, evidence suggests that localized muscle cramping may be more closely associated with exercise intensity and prolonged duration resulting in muscle fatigue than electrolyte imbalance.
According to this new hypothesis, when muscles are tired, the nerves that control them can get excited, leading to involuntary or uncontrolled muscle contraction or spasms—thus, muscle cramping. While this means that consuming electrolytes may not prevent or relieve cramping, exercise-associated muscle cramps can be relieved with rest and passive stretching. Ensuring adequate pre- and during-exercise fueling can also offer a preventive strategy to lessen muscle fatigue and reduce the risk of muscle cramps.
Preventing Muscle Fatigue
2-3 HOURS BEFORE EXERCISE: Eat a proper pre-exercise fueling meal balanced with lean proteins, complex carbohydrates, healthy fats, and colorful fruits or vegetables. An excellent choice would be scrambled eggs, whole wheat toast with peanut butter and a cup of fresh fruit.
0-1 HOUR BEFORE EXERCISE: Eat a light, carbohydrate-based snack such as a banana or small handful of pretzels.
DAILY HYDRATION: Drink ½ to 1 ounce of water per pound of body weight per day.
PRE-EXERCISE HYDRATION: Drink 8 to 16 ounces of water for every 100 pounds of body weight in the one to two hours before exercise so you begin your session optimally hydrated.
DURING EXERCISE HYDRATION: Calculate sweat rate to determine optimal fluid intake during exercise (pre-exercise weight minus post-exercise weight, plus amount of water consumed during exercise).
SPORTS DRINKS: Choose a sports drink instead of water when training for more than one hour, during very intense training, or in conditions of extreme heat and humidity. Look for products containing at least 110 to 240 milligrams of sodium and 15 to 20 grams of carbohydrate per 8-ounce serving to replace sodium and chloride lost in sweat, as well as to keep you adequately fueled throughout the session or competition to prevent muscle fatigue.
While there is still much left to debate regarding the cause of muscle cramping, most athletes do fall short of getting adequate amounts of calcium, potassium, and magnesium. They can still benefit from more of these nutrients, along with ensuring adequate hydration. Below are some foods rich in these electrolytes:
Dairy products – milk, cheese, and yogurt
Milk and yogurt
Beans and legumes
Bergeron, M. F. (2008). Muscle cramps during exercise-is it fatigue or electrolyte deficit? Current Sports Medicine Reports, 7(4), S50-S55.
Schwellnus, M. P., Drew, N., & Collins, M. (2010). Increased running speed and previous cramps rather than dehydration or serum sodium changes predict exercise-associated muscle cramping: a prospective cohort study in 210 Ironman triathletes. Br J Sports Med, 45(8), 650-656.
Schwellnus, M. P. (2009). Cause of exercise associated muscle cramps (EAMC) – altered neuromuscular control, dehydration or electrolyte depletion? Br J Sports Med, 43, 401-408, doi:10.1136/bjsm.2008.050401.
Noel Williams, MS, RD, CSSD, LD is a Performance Dietitian at Children’s HealthSM Andrews Institute Sports Performance Powered By EXOS. She earned both her BS in Nutrition and Dietetics and her MS in Exercise Physiology and Sports Nutrition from Montana State University. She conducted her Master’s research on cardiovascular and metabolic demands of Rocky Mountain Elk Hunting. Noel is a Board Certified Specialist in Sports Dietetics, and has taught workshops on developing positive eating behaviors in children in partnership with Montana Team Nutrition. She is also a part of the following professional organizations:
•Academy of Nutrition and Dietetics
•Texas Academy of Nutrition and Dietetics
•Sports, Cardiovascular, and Wellness Nutrition Dietetic Practice Group (SCAN)