What you need to know about working out where it's hot and humid

November 13, 2017

Bangkok is hot. So hot, in fact, that it earned the title of World's Hottest City based on annual mean temperature, according to the World Meteorological Organisation (WMO). When you combine the extreme heat with oppressive humidity that can top 90 percent on some days, Bangkok can certainly be an uncomfortable place to be.

The combination of heat and humidity also poses certain health risks — dehydration, heat exhaustion and heatstroke, to name a few — when you're working out or engaging in physical activity. Here is what you need to know to keep your workouts safe and avoid potential health issues.

How the body cools itself

Our bodies have a built-in cooling system that relies on perspiration to keep us cool and avoid overheating. The process of sweating pushes heat to the skin, and the heat gets carried away by the cooler outside air passing over the skin.

When it's hotter outside, the body must work harder and use more fluid to speed up the rate of perspiration. And when the humidity is high, it takes longer for the perspiration on the skin to evaporate. That's why we feel warmer when the humidity is high and don't feel the usual cooling sensation even though we're sweating more than usual.

Six tips for safer workouts in Bangkok — or wherever it's hot and humid

1. Be early or late: Avoid activity during the hottest part of the day, from around 11:00 am to 15:00 pm, when the mid-day sun brings the day's hottest temperatures. Whether you choose to work out indoors or outdoors, the early mornings and evenings are the coolest (and safest) times of the day for a healthy workout. If you prefer evening exercise, try to finish your workout at least four hours before your usual bedtime to avoid potential sleep problems.

2. Remember the sunblock and sunglasses: Before heading outside during the day, be sure to apply sunblock to protect against skin cancer. Wear authenticated UV protected sunglasses to prevent injury to eyes from direct sunlight.

3. Bring the workout indoors: When it's hot and humid outside, the safest place for a workout is inside where it's cool and air-conditioned. Bangkok's high heat and humidity can trap air pollution , so keeping the windows closed will help keep the indoor air as pollution-free as possible.

4. Stay hydrated: The hot and humid conditions force your body to use more of its stored liquid to try to keep the body cool, so it's critical to drink plenty of water — before, during and after working out — in order to replenish the lost fluids. Water is clearly the optimal drink-of-choice for staying hydrated; sports drinks might offer some added electrolytes and minerals that your body loses during sweating, but these types of drinks contain significant amounts of added sugar, artificial flavors and colors that are best avoided. Fresh fruits and vegetables are rich in vitamins and minerals, which makes them the best source for replenishing the vitamins and minerals the body loses during a workout.

5. Don't push your limits: The heat and humidity force your body to work harder to keep you cool, so you should protect your health by adjusting your workout intensity and duration. A 30-minute workout is long enough to stay fit and healthy; workouts beyond 60 minutes in high heat and humidity can push the body beyond its ability to stay cool and increase the risks of potentially-dangerous heat-related health problems.

6. Know the danger signs: Dehydration, heat exhaustion and heatstroke are the primary health threats related to excessive physical exertion in hot and humid conditions, when the body becomes unable to keep itself cool and loses too much fluid.


Dehydration tends to be the first, and least serious, issue related to working out in high heat and humidity. Its most common symptoms include fatigue and weakness, dizziness, fainting and dark-colored urine; if you are dehydrated, move to a cooler place, if possible, and drink more water. If your body temperature doesn't cool down, or if you have a fever, you should seek medical attention.

Heat exhaustion

Heat exhaustion is more serious than dehydration and is related to either water depletion or salt depletion. Its symptoms may include confusion, cramps, dizziness, fainting, nausea or vomiting, extreme sweating, and a rapid heartbeat. Heat exhaustion requires quick action: find a cooler place (preferably air-conditioned) to rest, drink plenty of water, remove unnecessary clothing, take a cool bath or shower, and use a fan or ice packs for further cooling.


If you don't feel significant relief within about 15 minutes, seek medical help right away, as heat exhaustion can progress to heatstroke . Heatstroke can cause brain damage, do harm to vital organs and, in the most serious cases, may be fatal. Dial +66 2011 5222 to call Bumrungrad’s Emergency Center to coordinate help.

Before starting a new exercise or workout regimen, it's always a good idea to talk to a doctor. To make an appointment at Bumrungrad, call +66 2066 8888, or book an appointment online via the Bumrungrad website.

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