-- Marathon Running Information, Coaching and Advice from Coach Joe English

Training — Dehydrate A Muscle and Lose Performance

running-advice-bugOne of our sharp-eyed readers watching the film Moneyball (perhaps on their new iPadHD) picked up on something on a wall and asked me a question about it. The movie relates to baseball and on the wall behind one of the players talking in the film there is a piece of paper with some statistics about dehydration on it. Apparently this would have been the Athletic Trainer’s way to remind their players to drink more fluid. The question that I was asked is whether the statements were true or if they were just Hollywood props on the wall of a movie set.

First, here is what the piece of paper actually said:
“Dehydrate a muscle by 3%
10% loss of contractile function
8% loss of speed
Performance dries up.”

Well, here’s my answer. First, many times Hollywood film-makers use consultants or do pretty good research in dressing out spaces and this is one of those cases. The facts that on the paper are correct. In a really good article on the website of the National Council of Strength and Fitness on Maintaining Proper Hydration those same statistics appear. The article starts by defining dehydration as a loss of 1% or greater of body weight due to fluid loss.

Here’s what the article has to say about those claims on the Moneyball poster: “Training in a state of dehydration can have dramatic effects on performance. Dehydrate a muscle by only 3% and you cause about 10% loss of contractile strength and an 8% loss of speed.” This is most likely the source of the poster on the wall.

The article then goes on to say something really interesting, which I’ll quote for you: “A study conducted at Ball State University showed a 7% drop in speed over 10 kilometers by runners who were dehydrated by just 2%-3%. That’s only 3-5 lbs. for a 165 lb. runner.” Think about this for a minute. Runners frequently lose 3-5 pounds on a long training run from fluid loss. And not only does this help illustrate how performance loss can happen during a run, it helps us remember why it is so important to re-hydrate after a long effort — because without re-hydrating after that effort the next day’s performance will definitely suffer as well.

A drop in performance of 7% over 10KM is a great deal for a performance athlete. This would be enough not only for the athlete to feel it, but to see it on their watch in a hard track session or tempo run. So perhaps the next time you’re feeling flat, or not hitting your pace targets, ask yourself if you’ve been drinking enough fluid and whether you feel like you’ve done a good job re-hydrating after your long runs.

Thanks to Moneyball for giving us another opportunity to bang the drum: nutrition and hydration are key to performance. Keep on eating and drinking runners.

Coach Joe English, Portland Oregon, USA
Running Advice and News


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