By Candace Chemtob, B.S. and M.S in Human Nutrition
If you have ever had a muscle cramp on the court, it is an event that will not be easily wiped from your memory. Muscle cramps have stopped many athletes in their tracks. Recently, the video footage of Rafael Nadal cramping at the US Open during a press interview went “viral” on you tube. Lucky for him, this did not happen on court.
Muscle cramping can cause excruciating pain and can bring a match to a quick end. A muscle cramp is defined as a sharp and sudden muscle pain, most often in the legs, but can occur in hands, arm, and abdomen (rib cage). The affected muscle normally feels hard or bulging. The causes of muscle cramping during exercise can be divided into three main categories: 1. Overuse injury and fatigue; 2. Nutrition related issues (electrolyte losses); and 3. Medical conditions.
Most muscle cramps are harmless and a quick recovery can be expected. Although it is rare, some muscle cramps can be caused by underlying medical conditions. If cramps are severe and recurrent, please consult your physician. Medical conditions that can lead to muscle cramping are inadequate blood supply caused by narrowing of arteries, nerve compression, medical illnesses such as nerve or kidney disease, hypothyroidism, diabetes, anemia, or low blood sugar levels. Some prescription medications may also cause cramps.
Most commonly, cramping is the result of muscle overuse or injury. Repetitive movements leading to muscle strain and fatigue can trigger cramping. A simplified explanation of this form of muscle cramping is as follows: repetitive muscle movement can cause “overstimulation” of the muscle leading to sustained contractions. Overuse muscle cramps come on suddenly—without warning. Risk factors associated with overuse injury/fatigue cramps are insufficient training, poor stretching habits, and cramping history. Overuse/fatigue muscle cramps develop suddenly and are in primarily one muscle group (often asymmetric, not on both sides of the body). Stretching, massage, and icing can lead to a quick recovery.
Muscle cramps associated with electrolyte deficits are commonly referred to as “heat cramps”. Many electrolytes have been implicated as the culprit of muscle cramps, but wrongly so. According to the American College of Sports Medicine (Bergeron, 2008), a significant loss of sodium through sweat is the primary cause of electrolyte induced cramps. Sodium is the most abundant electrolyte in sweat (followed by chloride) and is important in transmitting signals from the nervous system that initiate muscle movement. Potassium, calcium, and magnesium are also lost in the sweat but in much smaller amounts. To give you an idea of the magnitude of difference, magnesium losses in sweat are 20 to 25 times less than that of sodium.
One study found that after a 90-minute training session soccer players had sodium losses that varied from 2 g to 10 g. This illustrates two main points. First, that the amount of electrolytes lost in sweat can vary greatly from athlete to athlete. Secondly, sodium losses through sweat can be significant. To put this in perspective, the average American diet contains 6 to 8 g of sodium per day, most of which is in the form of table salt (sodium chloride). If sodium losses in sweat exceeds sodium intake from the diet, the result can be a total body sodium deficit.
Experts believe that several factors put an athlete at risk for “heat” cramps, such as prolonged exercise in a hot/humid environment, high sodium sweat content, and a lower dietary sodium intake. Muscle cramps caused by electrolyte deficiency do not develop as suddenly as overuse cramps. These cramps gradually increase in intensity and can be more symmetrical in the muscles affected. Stretching, massage, and icing may lead to some relief but it is not complete.
Heat cramps are the earliest sign of heat illness. If heat cramps are suspected, this is not a situation that should be taken lightly by players or coaches. Heat illness, untreated, can progress to heat stroke. Heat illness needs to be considered even on an air conditioned squash court. Regardless of the usual cooler playing conditions on squash courts, significant sodium losses can occur. If you suspect heat cramps, stop playing immediately, go to a cool or air conditioned spot, drink a sports drink containing sodium (like Gatorade) or simply add 1 teaspoon of salt to one quart of water, and it is advised to check body temperature (www.nlm.nih.gov).
Muscle cramps may not just be a painful inconvenience that brings your game to a sudden halt. Cramps are a way of our bodies telling us that something has to change; it cannot continue with the match or training. More than likely, muscle cramps are the result of overuse injury and fatigue and will resolve quickly. However, it is always best to be well informed and, if muscle cramps are sudden, severe, and recurrent, or you are at risk for heat cramps/ illness, please seek medical help.