Saturday, August 18, 2007

Hyponatremia

I've had this problem for a while now: When I exercise, be it cycling, swimming, or even yoga, I'll often find myself later in the day developing spontaneous muscle cramps.

Essentially, it's any prolonged endurance sport, but oddly it doesn't matter the pace. I went on a ride with Kristine to Buda and focused on keeping a gentle pace, spinning the pedals at a high cadence with relatively low load (it's really good for my knees) but even then, later in the day I was sitting and playing a board game and one of my hamstrings seized up. I spent the next ten or twenty seconds trying to act like everything was OK while straightening my leg very slowly under the table.

This has been going on for a while. I know cramps are usually caused by electrolyte imbalances, but I think I eat a reasonable amount of salt in my diet. Before exercising I usually have some carbohydrates that inevitably include some sodium, and if it's anything of any serious intensity or duration, I'll bring a bottle of energy drink, and I pick brands that have more sodium than most, because I know my sweat is saltier than average. After exercising, my skin is like a salt lick. But I just didn't think that could be the problem.

I started stretching after exercise, a little yoga sequence that thoroughly stretches the legs, shoulders, and hips. It didn't really seem to help a whole lot.

Finally, on a whim, after a challenging ride, I put 2 whole tablespoons of salt in my protein shake. It tasted absolutely revolting, but lo and behold, no cramps.

Ian suggested salt tablets, so I googled around, looking for information on athletes taking sodium supplements. I discovered that a state of sodium deficiency is called hyponatremia, and leads to headache, cramps, and malaise. Bingo. But the websites said that hyponatremia is not a condition normally experienced as a result of normal exercise, and that rarely do athletes need to explicitly supplement their diets with additional sodium.

Nonetheless, I've been drinking a glass of salt water (maybe a tablespoon of salt or slightly less) after all substantial exercise and the cramping is gone, as are the headaches I always just assumed were normal, a result of the heat, or neck strain, or something. I guess not! I know my mother has a thyroid disease that she takes medication for, and one of its symptoms is an increased craving for -- and legitimate physiological need for -- more sodium in her diet. And thyroid disease is congenital. Maybe I have a mild case of that.

Come to think of it, I've always suffered from cold extremities due to low blood pressure, and I've always heard an excess of sodium is correlated with increased blood pressure, so maybe that's related, too.

On the upside, I don't need to worry about moderating my sodium consumption.

Now, if only there were an analogous condition for a deficiency of ice cream. And if only I suffered from it.

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