By Dr Catherine Gonzalez *

Ever seen the exhausted runners staggering around Hoàn Kiếm Lake, Hà Nội, on a hot summer evening? Outdoor exercise can be challenging when the temperature soars and the pall of humidity descends on the city. So stay safe during hot-weather exercise by drinking enough fluids, wearing proper clothing and timing your workout to avoid extreme dehydration.

Even during that friendly round of golf, you might not notice the temperature rising — but your body will. If you exercise outdoors in the heat, use caution and common sense to prevent heat-related illnesses.

Exercising in hot weather puts extra stress on your heart and lungs. Both the exercise itself and the air temperature increases your body temperature. To dissipate heat, more blood circulates through your skin. This leaves less blood for your muscles, which increases your heart rate. If the humidity is high, your body faces added stress because sweat doesn’t readily evaporate from your skin — which only pushes your body temperature higher.

Under normal conditions, your skin, blood vessels and perspiration level adjust to the heat. But these natural cooling systems may fail if you’re exposed to high temperatures and humidity for too long. The result may be a heat-related illness, such as heat cramps, heat exhaustion or heatstroke.

How to avoid heat-related illness

To keep “cool” during hot-weather exercise, keep these basic precautions in mind:

1.        Slow and Easy. If you’re used to exercising indoors or in cooler weather, take it easy at first. As your body adapts to the heat, gradually increase the length and intensity of your workouts. If you have a chronic medical condition or take medication, ask your doctor if you need to take additional precautions.

2.       Drink plenty of fluids. Your body’s ability to sweat and cool down depends on adequate rehydration. Drink plenty of water while you’re working out — even if you don’t feel thirsty. Consider sports drinks for longer work outs. These drinks can replace the sodium, chloride and potassium you lose through sweating. Avoid caffeine or alcohol, which both actually promote fluid loss.

3.       Dress appropriately. Lightweight, loose-fitting clothing promotes sweat evaporation and cooling by letting more air pass over your body. Avoid dark colors, which can absorb the heat. Wear a light-colored hat.

4.       Avoid midday sun. Exercise in the morning or evening — when it’s likely to be cooler outdoors — rather than the middle of the day.

5.       Wear sunscreen. Sunburned skin decreases your body’s ability to cool itself. If you’re concerned about the heat or humidity, stay indoors. Work out at the gym, walk laps inside the mall or climb stairs inside an air-conditioned building.

How do I know when I need to stop exercising?

During hot-weather exercise, be on the lookout for heat-related illness. Signs and symptoms may include: Weakness, headache, dizziness, muscle cramps, nausea or vomiting. Rapid heart beat. If you suspect a heat-related illness, stop exercising and get out of the heat. Drink water, and wet and fan your skin. If you don’t feel better within 30 minutes, contact your doctor. If you develop a fever higher than 102^oF (38.9^oC) or become faint or confused, seek immediate medical help.

Regular physical activity is important — but don’t let hot-weather workouts put your health at risk.Be sensible about exercising in the heat. — Family Medical Practice Vietnam.

*Doctor Catherine Gonzalez is a General Practitioner at Family Medical Practice Hanoi.

For more advice on any medical topics, visit Family Medical Practice Hanoi on 298 Kim Mã, Ba Đình or call (024) 3843 0748. Email: hanoi@vietnammedicalpractice.com

FMP’s downtown HCM City location is at Diamond Plaza, 34 LêDuẩn, District 1; Other facilities are at: 95 Thảo Điền Street, District 2. Tel: (028) 38227848. E:hcmc@vietnammedicalpractice.com

FMP Danang is located at 96-98 Nguyễn Văn Linh Street, HảiChâu District, Đà Nẵng. Tel: (0236) 3582 699. E: danang@vietnammedicalpractice.com.