Originally Posted by
big john
I agree with most of your post with a couple of exceptions. First, I think hyponatremia is extremely rare with cyclists. I've heard of it, once with a friend who was part way through RAAM and had to be hospitalized and another time with a guy who was doing a 150 mile climbing ride on a hot day and he wasn't eating. I think if a cyclist is eating or at least taking electrolytes the risk is minimal. I know people have died from it during marathons, but these are people who spend 6+ hours running with nothing but water.
The other thing is the "drink only when thirsty" idea. This may work for some but certainly not everyone every time. When I do a hot climbing ride I cannot keep up with the fluid loss and have to start forcing water early in the ride. I typically come home from a hot ride (6 hours, more or less) 5 or 6 pounds lighter. I tried to ration water once, still drank a bunch, and was 11 pounds lighter after the ride. To me, thirst doesn't enter it and I must make a conscious effort to drink.
The adage still applies: "eat before you're hungry and drink before you're thirsty". That's because it takes a while for nutrients and moisture to get into the muscles or other places they're needed. A lot times, by the time you feel thirsty it's too late as your body fluid level is quite low and your electrolyte balance is out of kilter. The risk increases if in order to try and restore your electrolyte balance, which plain water won't do, you drink copious quantities of water which can cause hyponatremia.
If you add salt to your water you MUST add potassium too because without the potassium the salt is worse than nothing. I use half 'N' Half available in the baking section of most grocery stores. I add it to the water only when I need it.
Cheers