Heat cramps, while likely not caused by heat alone, are a subcategory of Exercise-Associated Muscle Cramps (EAMC). The exact mechanism of muscle cramps in warm environmental conditions is unknown, but can be caused acutely by extensive dehydration and sodium losses or chronically via inadequate electrolytes in the athlete’s diet. Although heat cramps are not a cause of sudden death, it can be confused with the more serious condition, exertional sickling (see Exercise Associated Muscle Cramps vs. Exertional Sickling below).
Heat cramps are painful, involuntary cramping often in the legs, arms, or abdomen with muscle contraction. Cramping usually occurs in the preseason conditioning phase when the body is not properly conditioned and more subject to fatigue. Heat cramps can easily be treated with rest, stretching of the muscle, and replacement of fluid and electrolytes.
How do you prevent heat cramps?
It may be impossible to completely prevent cramping from occurring; however, certain factors can be modified in order to reduce the incidence of future heat cramps.
The most effective ways to prevent heat cramping in athletes include:
- Acclimatizing the athlete to warm/hot environments if their sports require exercise in hot environmental conditions can help prevent heat cramps. Heat acclimatization protocols can be found here.
- Undergoing exercise periodization where the athletes training load gradually progresses in intensity and duration before requiring the athlete to perform all out in an event or an extensive workout session.
- Educating athletes on the proper replacement of fluids and electrolytes lost in their sweat. An athlete’s whole body fluid losses can be calculated using this sweat loss equation, however individual electrolyte losses are difficult to determine without individualized testing. Each athlete slightly differs in the amount of sweat and salt losses during exercise. Keep in mind that these factors may change depending on the temperature and humidity of the ambient environments, so sweat testing should be specific to the conditions in which the athletes are exercising.
- Maintaining balanced electrolyte levels via consumption of electrolyte rich drinks before and during the athletic event or practice session will reduce the likelihood of electrolyte imbalance and dehydration, especially during activities lasting longer than one hour. Certain individuals naturally expel more sodium in their sweat compared to the average individual. These people may need to supplemental with extra sodium in their diet or fluid replacement beverages.
- Removing excess clothing during physical activity may help reduce the chance of getting heat cramps by allowing for more efficient evaporation of sweat produced, which would result in a lower internal body temperature during exercise. For example, if a field hockey goalie is performing conditioning drills during which protective equipment is unneccessary, the athlete should remove the equipment during this portion of the conditioning session.
What puts an individual at risk for heat cramps?
- Exercise in the heat when the individual is not accustomed to exercising in hot conditions
- Profuse sweating or body water loss during exercise coupled with large electrolyte losses.
- Consuming a diet that is chronically low or inadequate in the amount of sodium or other electrolytes required by the body for sweating. In other words, the daily sodium balance is not maintained as sweating demands increase in an effort to maintain a normal exercising body temperature.
- Exercising for an extended duration of time or participating in multiple practice sessions per day without properly replacing electrolyte and water losses
- Muscular fatigue
- Wearing additional layers of clothing, protective gear, or equipment
Look for these symptoms in athletes when heat cramps are suspected:
- Dehydration, thirst, sweating, transient (short term) muscle cramps, and fatigue
- Painful, involuntary muscle spasms (usually occurring in the legs) associated with exercise in the heat when athletes have been sweating profusely
- A precursor to the initial onset of cramps involves muscle twitches or fasciculations. If this occurs, remove the athlete from the heat and encourage rehydration with an electrolyte beverage
Exercise Associated Muscle Cramps vs. Exertional Sickling?
Exercise associated muscle cramping is often confused with exertional sickling but may be differentiated by the following ways.
|Pain Factor||More excruciating pain; can be pinpointed to a location||Pain is strong, however, is more generalized over body|
|State of Muscles||Muscles “lock-up”; sustained and visibly contracted and rock hard; athletes hobble to a halt or fall.||Muscles are weak; athletes slump, push through instances of collapse|
|Physical Symptoms||Athletes may writhe or yell in pain||Sickling athletes lie fairly still without yelling|
|Prodrome of Muscle Twinges||Yes||None|
|Occurrence during Workout/Session||Occurs during or after intense workouts (after 30 minutes)||Generally occurs within first half hour during intense workouts|
|Body Temperature||Athlete’s core temperature is elevated||Athlete’s core temperature is not greatly elevated|
How do you treat the individual?
- Remove the athlete from exercise session and have them rest in the shade or an air-conditioned room.
- Stretch, massage and knead the muscles that are cramping in its full-length or stretched position (joints should be extended).
- Provide the athlete with fluids, such as water and an electrolyte sports drink to replace those lost during sweating.
- Provide food high in salt content to replenish the electrolytes lost from sweat. If this is not available, consider providing a solution of 1/2 teaspoon salt dissolved in 16-20 ounces of water prior to or post cramping.
- In cases of heat cramps that persist, use ice massage on the affected muscle.
When can the individual return to activity?
Once an athlete has rested and replenished the fluids and electrolytes lost from their sweat, they can usually return to play during that same exercise session or practice. It is likely for the athlete to experience persistent cramping if fluid and electrolytes have not been adequately replaced. Determining the athlete’s sweat rate could be beneficial for their knowledge in understanding their body’s requirement of fluid during exercise and how to appropriately replenish water stores and electrolytes following exercise.
- Armstrong LE. Exertional Heat Illnesses. Human Kinetics; 2003.
- Armstrong LE, Casa DJ, Millard-Stafford M, Moran DS, Pyne SW, Roberts WO. American College of Sports Medicine position stand: exertional heat illness during training and competition. Med Sci Sports Exerc. 2007;39:556–572.
- Binkley HM, Beckett J, Casa DJ, Kleiner DM, Plummer PE. National Athletic Trainers’ Association position statement: exertional heat illnesses. J Athl Train. 2002;37:329–343.