Have a question about running? You're in the right place. Every Tuesday, world-renowned coach, author and athlete Hal Higdon posts and answers athlete questions here. You can submit your question by joining the discussions on Hal Higdon's Virtual Training Bulletin Boards.
Why is it that the longer I run in the heat, the less I sweat? I start out dripping sweat from every pore. But after an hour or so, my sweating seems to decrease dramatically. I feel like I'm drinking plenty of water. Is it just that my body needs to adapt to the heat?
Yes, our bodies do seem to adapt to the heat. Somewhat. Thus, we are discomforted by warm weather less toward the end of the summer than at the beginning of summer. Or maybe we learn to manage the heat better: slowing down, drinking more, running at times of the day that are cooler and without the sun beating down on our heads.
But a red flag just went up, because what you describe (no sweat) is the early stage of dehydration, which can lead to heat stroke. Sorry to scare you, but sweat is an important part of our body’s air conditioning system. We sweat. The sweat evaporates. This cools us. We need to drink to maintain this air conditioning system. Fluid out requires more fluid in. Unfortunately, under very warm conditions, the body cannot process fluids fast enough to match sweat loss. Sweating decreases—as you have discovered. As a result, body temperature increases. In extreme conditions, the body temperature may rise to dangerous levels. You need to slow down, stop, get off the course, find shade, sit down, seek help. It’s 9-1-1 time. Dehydration can prove fatal.
Dry skin, the result of no sweat, very definitely signals a dangerous condition—a red flag—that we need to learn to recognize, both in ourselves and in other runners around us.