[Sportsandrec] How Much Water?

[Thornbury, Kelly]

I'm working on rewriting a paper I wrote a while back on hydration, but the original was over 20 pages, lots of science, and had over 150 study references...Hopefully it (the rewrite) may end up in a future issue of Competition Corner. 

So yes, drinking too much can cause death (no, not the same as drowning), however, a normally healthy body will not retain excess water, but medical conditions, medications, and extreme, purposeful over drinking (like the contest for the video game) can be exceptions. The body, without replenishment, has a certain amount of electrolytes (like sodium and potassium), which are lost through excretion (urination and sweating are the two biggest means of loss). Fluid imbalances change the concentrations of electrolytes in the body...minor imbalances can be easily controlled but extreme imbalances are hard on the body. 

Everyone is different on the amount of fluids they should consume for workouts, but general recommendations are if you are a "big sweater" you should drink more; well trained endurance athletes sweat more and at lower workloads, but their bodies have adapted to retain more water in a euhydrated state. I tell people to check the scale before and after their workouts, and drink enough fluids to be at least within 97% of their pre-workout weight (personally, I go for 100%) before ending your rehydration schedule or beginning future workouts. This is about a quart of water for every 2 pounds lost, or for us metrics, about a liter per kilogram of fluids. A typical "fat-burning" workout will not burn enough calories to lose a pound of real body weight within one session. For example, to burn the calories in 1 pound of fat would take a 150 pound person running at 6 mph almost 5 hours...so don't worry about leaving the gym weighing exactly what you weighed going in, your weight loss comes from multiple sessions through the weeks and months. 

The body also can not really absorb more than about 1 liter (1qt) of fluids per hour, which means you shouldn't try to put all the weight back on instantly, but plan on your rehydration schedule to be about 1 hour per 2 pounds lost. Room temperature water absorbs into the system faster than cold water; adding glucose (no more than an 8% solution) also speeds absorption (Gatorade is 6%); electrolytes should probably be considered for profuse sweating or for workouts lasting more than an hour. 

How much water...If your urine is really dark colored, if you feel slightly dizzy after your workout, if you sweat a lot, or you have an untypically high pulse and low blood pressure, drink more fluids. 

As for whether or not you are dehydrated...statistically, most likely, since about 3/4 of Americans are in a chronically dehydrated state. (The odds were in my favor on guessing that one :)

Kelly