Heat cramps are the intermittent, involuntary spasm of muscles that occur in an individual who is physically active (for example, working or exercising) in hot or humid weather. They are often associated with dehydration. Heat cramps usually affect the major muscles that are being stressed in the hot environment.
Most often these are the thigh and leg (quadriceps, hamstrings, gastrocnemius), the core muscles (abdominal wall and back) and the arm muscles (biceps, triceps).
Heat cramps can also occur after the activity has been completed. For example, construction workers or roofers can develop cramps a few hours after their work shift is over.
Who is at risk for heat cramps?
While heat cramps tend to affect those who are active in a hot environment, it should be noted that heat cramps are one of the symptoms associated with heat exhaustion as part of the spectrum of heat-related illness.
Those individuals who have impaired temperature control mechanisms are at higher risk for developing heat-related illness. The body’s most effective way of cooling itself is through sweat, and then the sweat evaporates into the environment. Those at most risk for heat cramps include:
- Infants and young children because they depend upon others to avoid the heat, dress them appropriately (avoid swaddling an infant since it prevents air movement over the skin to promote sweat evaporation) and provide enough fluid to drink
- The elderly because they may have underlying medical conditions, including heart and lung disease, and they can easily become dehydrated
- People who live by themselves or who cannot afford air conditioning are at higher risk for heat related illness
- A variety of medications can impair the body’s sweat and heat regulation. Examples of drugs include medication prescribed for psychiatric conditions, including antipsychotic medications and tranquilizers. Over-the-counter cold medications and antihistamines also impair the body’s temperature control mechanism.
- Alcohol consumption
What causes heat cramps?
While it was thought that dehydration and electrolyte imbalance was the cause of muscle cramping, there are alternative theories as to why muscles cramp when the body is exposed to heat.
Since heat cramps begin after significant exercise in a hot environment where the affected individual begins sweating profusely, the theory was that muscles were depleted of water and sodium affecting their ability to contract and relax.
Some new research suggests that as the muscles tire from excess activity and work, the ability for the muscle to regulate its own contraction is lost and this is called altered neuromuscular control.
Regardless of the cause, the diagnosis and treatment for heat cramps remain the same.
How do you prevent heat cramps?
It may be impossible to completely prevent a cramp 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.
Similar to heat acclimation, acclimating to exercise by gradually progressing intensity and duration before requiring the athlete to perform all out in an event or extensive workout session healp prevent heat cramps.
This process may also help prevent athletic injuries!
Educating athletes to replace fluids and salt lost in their sweat. This can be done by calculating whole body sweat loss during exercise using this sweat loss equation.
Each athlete slightly differs in the amount of sweat and salt losses during exercise. Also keep in mind that these factors change depending on the temperature and humidy of the ambient environments, so sweat testing should be specific to the conditions in which the athletes are exercising.
Maintain a balanced electrolyte level by consuming electrolyte rich drinks before and during the athletic event or practice session if physical activity lasts longer than one hour in duration.
Certain individuals naturally expel more sodium in their sweat compared to the average individual. These people may need supplemental/extra sodium in their diet.
Removing excess clothing during physical activity may help reduce the chance of getting heat cramps by allowing for greater evaporation, keeping core body temperature lower 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.
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.
When should an individual seek medical care for heat cramps?
Heat cramps can usually be treated when and where they occur. The affected individual should stop all activity and find a cool place to rest. The muscle cramps and spasms can be overcome by gently stretching the cramped muscle(s).
Individuals can often replace their fluid loss by drinking a combination of water, sports drinks, or other electrolyte replacement solutions.
If the cramps cannot be controlled, the affected individual should seek medical care. There is no specific condition that differentiates heat cramps from heat exhaustion.
The symptoms of these conditions form a spectrum from mild to moderate heat-related illness and symptoms can overlap. Severe heat cramps may actually be heat exhaustion.
This is especially true if the person has nausea or vomiting and cannot replace the fluid loss, if they have significant fatigue and weakness, or of they have profuse sweating that does not stop when placed in a cooler environment.
Heat stroke is a true medical emergency and can be deadly. The body’s ability to cool itself no longer functions, and as the temperature spikes, sometimes greater than 106 F (41 C), confusion and coma can occur.
Emergency medical services should be activated (call 911) immediately if an individual is thought to have heat stroke. While waiting for help to arrive, the person should be moved to a cool place, clothes should be removed to help air circulate over the body, and cool water should be sprayed or sponged onto the body to attempt to cool it.
Prevention is the key to avoiding heat cramps, or other heat-related illness. A person who has had heat cramps is more prone to developing them again.
Some professions are at higher risk for heat cramps, for example, construction workers and roofers are potentially exposed not only to the heat from the sun but also from the radiant heat from the hot shingles and liners on the roof.
It may be helpful to acclimate to the hot environment over a period of days to allow the body and its muscles to adapt to its water and electrolyte needs.
How are heat cramps diagnosed?
The diagnosis of heat cramps is usually made after taking the patient’s history. It is important to know about the environment where the person affected by heat cramps was working, exercising, etc..
How do you treat the individual?
Remove the athlete from the exercise session, workout, or practice and have them rest in the shade or an air-conditioned room.
Stretch, massage and knead the muscle that are cramping in its full-length position (joints should be extended).
Provide the athlete with cold fluids, such as water or an electrolyte sports drink to replace sweat losses.
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.
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 after exercise.
What are the complications of heat cramps?
There are few long-term consequences of heat cramps, however, once a person experiences heat cramps, they may be at risk for future episodes.