Running and hyponatremia

I’m back to running outside again, now that the weather is reasonably nice and feeling like some exercise would be a helpful thing for improving my mood.
Things have been going quite well, on the whole, as I’ve expanded my routes to include parts of Rock Creek Park, which has some very nice trails. It’s gratifying tracking one’s progress and routes on www.gmaps-pedometer.com, but I was disappointed to find that a number of the trails in the park are not included on the site. Which is a shame because it’s generally more interesting to run on trails in the woods than it is running on a flat paved surface. And since I no longer have the problems with my ankles (spraining them easily), I definitely would prefer more varied terrain.
The good news is that I’ve run just about 50 miles so far in March, which I’m quite pleased with. The bad news is that I went for a longish run yesterday (11 miles at a moderate pace, in an hour and forty-five minutes), not too different from a run I did on Friday. However, I failed to eat lunch before going (since I left at around two) and didn’t fully realize what that would do. I felt okay during the actual run, but after I got home I started feeling rather unwell.
They’ve turned on at least some of the water fountains in the park, which is nice, but I think I ended up with my electrolytes badly out of balance. Apparently it’s called hyponatremia (lack of sodium), and in extreme cases has led to people dying. My case was clearly not that severe, but I did feel quite unwell, and couldn’t really eat too much at dinner (out with Beth’s family as usual on a Sunday night). After dinner we went to Beth’s parents’ house in order to file our taxes (sadly not getting as much of a refund as we’d hoped, but it will certainly help), where I drank some gatorade, which seemed to help a fair bit.
By the time we got home in the evening (and skyped Josh to wish him a happy birthday and see Henry jumped up on birthday cake), I thought I was feeling a little better and had some more to eat, but it was a short-lived thing, and by the time we went to bed I wasn’t really feeling able to sleep at all, and I ended up passing a fair bit of the night reading about energy gels and salt tablets and what I should be doing when running in the future. And I’m stuck at home today because I feel pretty thoroughly rotten.
I don’t know what kind of selection (of energy gels and salt tablets etc) I’ll be able to find at a grocery store, so I may have to go to to a specialty store, or just order online. I think that in general I should perhaps be putting a bit more thought into my runs and spend at least a little time reading some training guides for half-marathoners and marathoners. It certainly wouldn’t hurt, and seeing as I have ended up pretty much stuck in bed for today, I have conclusively demonstrated that failing to think about these things can hurt.
I think that a lot of the problem comes from the fact that I’m not used to running/cardio workouts that are in the region of two hours, uninterrupted. I’m going to have to find some way to bring fluids and energy with me on these runs if I’m going to avoid this kind of problem in the future. I definitely need to find some way to carry water/gatorade/something with me on these runs. I suspect a trip to Roadrunner will be required shortly.

Interestingly, one might think that the high-sodium diet which is ubiquitous in the US would lead to avoiding these sorts of problems. However, apparently if you have high sodium in your diet normally, you will end up with saltier sweat as a rule (because your body is trying to get rid of the excess), which then means that you will lose all the more when you’re sweating lots on a long run. The better thing to do is to move to a low-sodium diet in general and make sure you have enough when working out. At least, that’s the impression I’ve gotten from the light reading I’ve done so far; as I said, I need to examine all this in more detail.