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Are cramps cramping your style?

While muscle cramps are poorly understood and difficult to predict, there are steps that runners can take to avoid them.

stomach cramps

cramping stomachBy Bobbi Barbarich

Just about anyone who moves has experienced a muscle cramp at one time or another, but runners are especially familiar with the debilitating spasms. While muscle cramps are poorly understood and difficult to predict, there are steps that runners can take to avoid them.

Here’s what we do know about muscles cramps: Running involves continuous contracting and relaxing of muscles. When the contractions become involuntary and do not relax, it’s called a cramp. Cramps can last a few seconds or several excruciating minutes, slowing your pace or even making you pull out of a race. The most accepted hypothesis is that cramps are caused by overexertion and stimulation among athletes who exert themselves to exhaustion. As a muscle tires, muscle fibres that should be working together as a unit become desynchronized from overstimulation, leading to quick-hitting pain.

So what makes the muscle’s fibres get out-of-whack? Dehydration is the most common suspect. Running causes fluid loss through sweat, as well as fluid shifts that disrupt the balance of electrolytes within contracting muscle cells also increase the likelihood of cramping. To understand how much water you need to drink while running, weigh yourself nude before and after a run – a one-kilogram weight loss is equal to one litre of water.

Well-hydrated runners can still get cramps if they have an electrolyte imbalance caused by a lack of sodium. Health-conscious athletes may restrict dietary salt to avoid high blood pressure, but a low-sodium diet can lead to cramps as sodium lost through sweat causes an electrolyte imbalance. Sodium depletion is most common in extreme endurance races, such as 100-mile trail runs, but can be a factor in runs lasting more than an hour.  To prevent low sodium, make sure you’re drinking 0.3 to 0.7 grams of salt per litre of fluid, especially in hot weather. Most sports drinks contain the right mix of sodium.

Calcium and magnesium may also play a role in the cramping equation. Low blood levels of either mineral increase nerve excitability and muscle stimulation. Calcium is also essential for muscle contraction. Renowned sports dietitian Nancy Clark says several athletes’ cramps faded after they increased their calcium intakes. “For example,” says Clark, “a ballet dancer who added yogurt and skim milk back into her diet reported her cramps disappeared. A mountaineer resolved his muscle cramps by taking calcium-rich Tums.” But Clark says exercise scientists are skeptical of calcium’s involvement in cramping. “A calcium imbalance is unlikely to be the cause of muscle cramps, since bones are a calcium reservoir and can supply the body what’s needed for proper muscle contractions.” Magnesium, on the other hand, is not stored in the bones, so low levels of this mineral may predispose runners to cramping.

Since the exact reason for each cramp is often unknown, it’s hard to find a fail-safe solution, but you can hedge your bets by staying well-hydrated, taking in some salt during longer runs and following a calcium- and magnesium-rich dietary plan. Take in at least two to three servings of low-fat, high-calcium dairy products every day, and seek out good sources of magnesium, such as nuts and whole grains. If diet isn’t the culprit, a physiotherapist or athletic trainer can assess whether running technique is a factor.

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