More than 70 percent of people have had a leg cramp at least once. Athletes are much more affected here. Many would probably wish they had a cramp just once and never again in their lives. A cramp can last from a few seconds to a few minutes.
Research on 2,600 endurance athletes found that two-thirds of endurance athletes get cramps. According to this examination, the calf muscles are most frequently affected.
Calf cramp: what is the cause?
There are a number of theories. The most common is that of electrolyte or fluid deficiency. Studies indicate that this deficiency – caused by heavy sweating, for example – can be associated with cramps under certain circumstances.
However, recent studies of cyclists and other endurance athletes found that athletes who lost more fluids or had lower electrolyte concentrations were not more prone to cramps than other athletes.
The role of nerves in spasms
Because the electrolyte thesis has never been fully proven, a more modern theory is gaining popularity: the fatigue thesis. The theory that the South African researcher Schwellnus developed in 1997 is primarily about the nerve cells that control the muscles. According to the thesis, malfunctions occur here before cramps occur.
In fact, the electrical activity measured in muscle during a spasm is significantly higher than that which can be developed during maximal voluntary muscle contraction.
How does a muscle cramp develop?
Muscle contractions are controlled by two "sensors": the muscle spindles and the Golgi tendon organs. When fatigued, the spindles may send out too many signals and the Golgi tendon organs too few. In the event of a cramp, the nerve cells send uncontrolled impulses to the muscle.
What causes cramps?
The better trained an athlete is, the less likely they will experience muscle cramps. This correlation has been calculated in many studies. There is no interaction between the frequency of seizures and the level of lactate in the blood. A lack of carbohydrates - the depletion of glycogen stores in the muscle - can also increase the risk of cramps. In studies, carbohydrate intake significantly increased the time under stress before cramps occurred.
Other cramp triggers can include new, unfamiliar movements, as well as blood pressure medication, cholesterol-lowering medication, asthma medication, alcohol, lack of sleep - but also the favorite drink of many racing cyclists: coffee.
Orthopedic Notes
If an athlete has frequent cramps, this can often be due to a "fault in the system", i.e. a chronic problem in the body.
For example: muscular imbalances such as shortened calf muscles, foot or pelvis defects.
Magnesium as a solution?
The fact that magnesium and other electrolytes such as potassium or sodium help against cramps is part of the traditional wisdom. But the majority of studies show that there is no relationship between cramps and the level of magnesium measured in the blood.
But here, too, there is an interpretation problem: magnesium is mainly found inside the cells, less so in the blood. A 2002 study found that well-trained endurance athletes excreted significantly more magnesium in the urine than recreational athletes. This speaks in favor of long-term prophylactic magnesium intake by people who are prone to cramps. Short-term income, on the other hand, seems to have no effect.
Sodium deficiency can actually trigger cramps. Many professional cyclists or triathletes therefore consume extra salt during a hot day of competition.
Fight cramps: how to avoid them
The risk of cramps can be reduced by exercising appropriately and avoiding overload. The first spontaneous reaction of the person afflicted by the cramp is usually the right one: stretch. This activates the Golgi tendon organs, causing them to send out signals that cause the muscle to relax.
Attention: In order to avoid activating the muscle spindles, you should always stretch slowly and carefully, not quickly and jerkily.
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