Hydration: How Much Do You Consume?

[Edit- this article is going to require more research.  As such, don't follow this advice yet.  :-)  ]

Figuring out how much liquid to consume is a topic of debate among runners. There are quite a few opinions out there, many involving a variety of formulas. I prefer to take a more individual approach- calculate your own needs. This is how I do it:

1. Before a run, strip naked and weigh yourself.

2. Go for a 5 mile run at your anticipated race pace without consuming anything.

3. Immediately after the run, weigh yourself (naked, of course).

4. Multiply your weight loss in pounds by 16, then divide by 5. That indicates the number of ounces you should consume per mile you run.

This is only a rough estimate and is dependent on training, temperature, and exertion level. Ideally you should drink enough to maintain body weight. If you're gaining weight during a run, you're drinking too much and run the risk of hyponatremia. Some weight loss is okay as slight dehydration isn't dangerous.

Other Measures

I do this five mile exercise occasionally to get a rough estimate of my fluid needs in conditions similar to race day. During races, I also use urine frequency and color as an indicator. In humid conditions, I know I typically urinate about once every 90 minutes and it looks like light yellow lemonade. In dry conditions, that time extends to about 120 minutes. In 100 milers, I've also brought a scale along to make sure I'm not gaining weight.

What About Drinking When Thirsty?

Many people use this method, and it usually sucks. Thirst is rarely an accurate indicator of hydration status. In my experience, most people over-drink if drinking when thirsty. Furthermore, the fatigue late in races tends to mess with your sense of thirst.

One last tip- lay off the ibuprofen. It messes with your kidney function. If you need pain medication to get through an ultra, you probably need to do a little more training.

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