Tuesday, June 22, 2010

Things Learned from the Philly Bike Race: Part II

I get a lot of questions about cramps. Muscle cramps. Leg cramps. Can you stop my cramping? Sure, but first let's review one of the most common cause of cramping and how to figure out if you need to look further into your cause of cramping. There are several causes of muscle cramps including altered stretch receptors, lactic acid build up, hyperventilation and sodium loss. By far, the most common are lactic acid build up and sodium loss. Let's focus on sodium for now. Sodium is an element in the body that exists bound to chloride to make sodium chloride, also known as table salt. The balance of sodium and potassium ions keep many cells alive and functioning well. Sodium plays a large role in muscle function to make muscles contract.
Sodium unfortunately has a been given a bad rap for its role in high blood pressure. As we look to cut sodium from our diets, we sometimes have a hard time keeping up with our sodium losses. If you've ever tasted your sweat, you know that there is a lot of salt in sweat. If you've ever tasted commercially produced uber-scientific electrolyte drinks, you know that they don't contain as much salt as they'd like you to believe. Different people have different amounts of sodium in their sweat, some more than others, some a lot more than others.

How do you know if you are a salty sweater? Your clothes are caked with salt stains. Look at this guy. He's a pro rider on the Jittery Joe's-Mountain Khakis team. Pay close attention to the salt stains on his sleeves.

Here's a closer picture of his salt stains. If I can see your salt, you qualify as a salty sweater.

Back to cramping.

When salt loss occurs, muscle contraction doesn't work very well. For some, the smaller muscles in the hands and face start to twitch. For others, muscles contract and can't relax.
There are about 10 grams of sodium stored in the body at any given time. A salty sweater may lose all of that salt over the course of long race. When that happens, the cramps come on.

What to do?
If we know how much sweat you lose in an hour of exercise (every pound lost equals 16 ounces of sweat) and we can collect and measure the sodium concentration in that sweat (lab testing), we can figure out how much salt you are losing. From there, we can replace not only the fluid you are losing, but also the salt you are losing. Cramps go away. You are happier than this guy.

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