Give or take a degree or two, your core body temperature should be around 37°C. If it climbs (or drops) just a few degrees, you’re in trouble. Exercise in hot conditions triggers a number of bodily reactions – the most important are increased blood flow to the skin (you may have returned home with a red face after a run) and sweating (you’ve certainly returned home sweating!).
Sweating is the fastest and most effective way for your body to rid itself of heat, but sweat must evaporate to have any beneficial effect. In high humidity (found nearly all the time in Singapore) sweat evaporates less easily; the result is that although we runners sweat profusely, our bodies do not cool off as quickly as they would in less humid conditions.
And as you continue to run in hot conditions, with your body producing more and more heat that cannot be dissipated, your internal core temperature can rise. At a certain point – 38-40°C – your body will overheat, sometimes with serious consequences, but at the very least, impairing your performance.
So what’s the best strategy for coping with hot and humid conditions?
• Try to pick the coolest time of day. In Singapore there’s not always a coolest time, but a few degrees can make a big difference.
• Hydrate all the time. Since your body cannot replace the fluid it sweats away during a run quickly enough, you need to be well-hydrated before you go out.
• Carry water, even on runs of only an hour.
• On long runs, choose a course that takes you past a place where you can regularly find water fountains, or buy cold water or a sports drink.
• Wear clothing that “breathes” and pulls the sweat away from your body.
• If you find yourself running slower than you did when you set your PB in Tokyo in February, don’t worry. It’s hot, you’re running slower. So what? At least you’re out there.
• If you get in trouble, stop and walk. Then find water as fast as possible. Then, get home as quickly as possible. There’s no shame in carrying taxi money. Lots of top runners do.
– Jeri
[First published on RUN Singapore, October 2019]