Heat Cramps

Heat cramps usually affect the major stressed muscles in a hot environment.

Heat cramps are the intermittent, involuntary spasms of muscles that occur in a physically active individual (for example, working or exercising) in hot or humid weather. They are often associated with dehydration. Heat cramps usually affect the major stressed muscles in a hot environment. Usually, these are the thigh and leg (quadriceps, hamstrings, and 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.

While it was thought that dehydration and electrolyte imbalance were the cause of muscle cramping, there are alternative theories as to why muscles cramp when the body is exposed to heat.

Some research suggests that as the muscles tire from excess activity or work, the ability of the muscle to regulate its contraction is lost, and this is called altered neuromuscular control. Regardless of the cause, the diagnosis and treatment for heat cramps remain the same.

Heat cramps are the earliest symptoms of the spectrum of heat-related illness:

• There is usually significant sweating with involuntary spasms of the large muscles in the body.
• The muscles that cramp are usually those that have been stressed.
• Runners and football players tend to get leg muscle cramps, but people who lift objects as part of their job can get cramps in the muscles of the arms or the core trunk muscles like the abdominal muscles (rectus abdominus).
• Heat cramps usually begin after a significant activity has occurred, but they also can occur hours after the activity has been completed.

If an individual has other signs or symptoms such as lightheadedness, weakness, nausea, vomiting, and headache he or she may be suffering from heat exhaustion. Affected individuals who have stopped sweating or who develop a fever and become confused may be developing heat stroke, which is a true medical emergency.

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 of developing a 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
• Elderly individuals may easily become dehydrated if they have underlying medical conditions, including heart and lung disease
• People who live by themselves or who cannot afford air conditioning are at higher risk for heat-related illness
• Taking certain 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

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. 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 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 if 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 a 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 illnesses. 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 to 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.

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 hot was it?
• How humid was it?
• Was there adequate air circulation?
• What activity was being performed and for how long?
• When did the cramps start? What muscles were involved?
• Was there associated sweating?
• Had the affected individual been acclimated to the hot environment?
• Was the person drinking enough water? One sign of heat cramps or a heat-related illness may be the color of urine. When the body becomes dehydrated, the kidneys conserve water and the result is concentrated, strong-smelling darker, yellow urine. If there is adequate water in the body the urine tends to be clear.

Often the physical examination will be relatively normal. The cramped muscles may be sore to touch and if there hasn't been adequate fluid replacement, the muscle may cramp again when taken through its normal range of motion. The physical exam may find signs of dehydration such as a dry mouth and tongue, lack of sweat in the armpits and groin, and decreased urine output. The vital signs can be a clue (for example, low blood pressure) and rapid heart rate (tachycardia). The affected person's blood pressure may be much lower upon standing compared to lying down (orthostatic hypotension).

Most first aid treatments for heat cramps can occur before seeking medical care:

• Stop the activity being performed
• Get to a cooler place
• Drink plenty of fluids
• Gently stretch the muscles that are cramping.

At the health care professional's office or a hospital, medical care focuses on symptom relief.

It makes it difficult to replace body fluids if the patient has nausea or vomiting, so intravenous fluids may be administered. Anti-nausea medications like promethazine (Phenergan), prochlorperazine (Compazine), droperidol (Inapsine), or ondansetron (Zofran) may be used to control those symptoms.

Painful muscles may be treated with over-the-counter anti-inflammatory medications, such as ibuprofen (Advil, Motrin, Nuprin, and others) or naproxen (Aleve, Anaprox, Naprosyn, Naprelan). Though it is a non-prescription medication, it is important to remember that there may be side effects or interactions with prescription medications. When you are not certain which medication to consider, consult your health care professional or pharmacist as a helpful information resource.

Heat cramps resolve with relatively simple treatments including rest, hydration, and stretching. It is important to remember that heat cramps are the initial presentation of heat-related illness and may progress to the more serious conditions of heat exhaustion or heat stroke.

There are few long-term consequences of heat cramps, however, once a person experiences heat cramps, they may be at risk for future episodes.

Prevention is the best treatment for heat cramps:

• If possible, try to avoid working or exercising in the heat of the day, but if it is required, acclimating to the hot weather is important.
• Drink plenty of fluids and if the activity lasts a prolonged period, consider using sports or balanced electrolyte drinks. This is especially true if significant sweating occurs and electrolytes are lost through sweat.
• Try to rest in cool or shaded areas whenever possible.