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Muscle Cramps
Causes
What causes muscle cramps?
To move your muscles, your brain sends signals to the voluntary muscles and coordinates the movements that you want. The voluntary muscles contract as they're being used and they become tighter. The muscles then relax when the movement is complete. When the contraction/relaxation cycles are done repeatedly, as in exercising, the fibers become stronger and the muscles get larger and stronger. However, sometimes the muscles, or just a few fibers within the muscle, contract on their own, causing a muscle spasm or cramp. The difference between a spasm and a cramp is the force of the contraction. If it's a quick contraction and release of muscle, without pain, it's a spasm. If the contraction is prolonged and painful, it's a cramp. Occasionally, cramps are so intense that you can't use your muscle because it's so tight and painful. Cramps can be short-lived, a minute or less, or as long as a couple of days. When researchers tested the cramping muscles of some athletes, they found rapid repetitive muscle firing, which could be described as the muscle fibers being hyperactive, in a sense.
Cramps can happen in one muscle, like the hamstring, or they can happen in a number of muscles together, like in your hands if you have writer's cramp. They can happen once and then not again, or there can be a series of on-again-off-again cramping.
There are several reasons why muscle cramps may occur, including the most common one that is seen in both professional and weekend athletes. These are called exercise-associated muscle cramping or EAMC. These types of cramps fall under the category of paraphysiologic cramps. Those are cramps that affect normally healthy people but are brought on by an event, such as exercise.
Researchers have estimated that marathon runners and triathletes may have a 30 to 67 percent lifetime risk of developing these cramps. Although the exact cause of the cramping isn't known, researchers do believe that they can be caused by inadequate stretching, muscle fatigue, or lack of oxygen to the muscle. Other causes can also include heat, dehydration, and/or lack of salt and minerals (electrolytes). New research suggests that there may be abnormal motor neuron (nerve) activity at the level of the spine.
Researchers also have noticed that the athletes who suffer from a lot of cramping tend to be older, marathon runners, or have a high body mass index. They don't stretch regularly, and have a family history of muscle cramps.
Cramps can also happen if you use the same muscles in the same way for too long a period. This could be as you crouch down to work in the garden, type on a keyboard, or write out long lists with paper and pen. The muscles contract and cause the pain.
Occasionally, these types of cramps seemingly come out of nowhere. For example, as we stretch, we often point our toes downward. This motion contracts the muscle in the calf of the leg and can cause a severe cramp or charley horse.