Extinguishing the dehydration debate: it’s heat baby!

With the unofficial end of summer upon us, I wanted revisit the great hydration debate. I saw many posts this summer about struggles with the heat, along with numerous other responses about drinking as the solution to most of the problems. Much of the advice was just the usual non sense about drinking and keeping cool, while other advice was bordering dangerous.

Most recently, my favorite site for misinformation, Competitor, had a coach discussing beating the heat Iron distance tris using hydration guidelines a decade out of date. Most significantly, and potentially dangerous, was the recommendation to “stay ahead” of your thirst. Based on the amount of contradictory and poorly researched information on Competitor sites, I recommend looking carefully at the author and be skeptical! I also take issue with Competitors claims that they have too many contributors to offer any articles on XTerra training, when any articles are simply reprinted. But I digress on this point, because I can find other sites to write for.

Now it is Labor Day and the hydration debate raged all summer but after a recent bad run I went back to baseline to get answers that didn’t surprise me. If its warm or hot and you feel terrible, I will guarantee that you’re not “dehydrated”, at least not significantly. I will bet that your body temp is higher (103+ d). Yesterday was hot but not the hottest day. My test run for my upcoming 1/2 marathon steadily degraded to terrible. In one hour, I lost over 3 lbs, or 1.5 L of sweat; this is my usual sweat rate, but I have about 30% higher rate on Brick runs. After my cool down walking and jogging the last mile (ie, cooling down), my body temp was a whopping 104.6 d! I did not drink during the run, but I also did not feel overtly thirsty, the major symptom of dehydration. But personal experience has shown me that drinking would not have done a thing.

My final word on hydration for this summer is don’t sweat it. I find that people use water as a crutch; if your exercising less than 45 min leave the bottle home. Sure, it’s nice to have drink on longer runs, but don’t fool yourself into thinking it will let you run faster or prevent overheating. Drink to thirst, and remember, carrying water on runs is more weight/work for the body because the driving force for heat gain is metabolic activity (HR is a good gauge here). Bring a small bottle and refill along the way. As for cycling, cooling is far greater due to evaporation, but at a given metabolic rate (ie, HR), sweat rates are similar (according to my experiments). For those interested, I have provided a link to the IMMDA Guidelines on hydration.

Happy Labor Day!

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