Wet Bulb Temperature and Exercise Safety: What You Need to Know

As temperatures rise during the summer months, staying active outdoors can become more challenging and potentially dangerous. While traditional temperature readings give us some insight into the heat, they don’t provide the full picture of the environmental stress our bodies might face. This is where wet bulb temperature comes into play. 

What is Wet Bulb Temperature?

Wet bulb temperature (WBT) is a measure that combines air temperature, humidity, wind speed, and solar radiation to give a more accurate representation of the heat stress on the human body. Unlike the regular temperature reading, WBT accounts for the cooling effect of evaporation. When humidity is high, the body’s ability to cool itself through sweat evaporation is diminished, leading to higher WBT readings.

Why is Wet Bulb Temperature Important for Exercise Safety?

The primary way our bodies cool down during exercise is through sweating and the evaporation of sweat. When the WBT is high, the efficiency of this cooling mechanism is reduced, increasing the risk of heat-related illnesses such as heat exhaustion, heat stroke, and dehydration. Understanding and monitoring WBT can help athletes and outdoor enthusiasts make informed decisions about when and how to exercise safely.

Understanding Wet Bulb Globe Temperature (WBGT)

Wet Bulb Globe Temperature (WBGT) is a more comprehensive metric that includes WBT, along with dry bulb temperature (the regular air temperature) and black globe temperature (which measures radiant heat). WBGT is often used in occupational health and sports settings to assess heat stress and establish safety guidelines.

Safe Exercise Guidelines Based on WBT

1. Low Risk (WBT < 25°C / 77°F): Safe for most types of exercise with standard precautions such as hydration and appropriate clothing.
2. Moderate Risk (WBT 25-27°C / 77-81°F): Increased risk of heat stress. Reduce exercise intensity and duration. Take frequent breaks and ensure adequate hydration.
3. High Risk (WBT 27-29°C / 81-84°F): High risk of heat-related illness. Exercise should be limited, and extreme caution should be taken. Consider indoor alternatives.
4. Extreme Risk (WBT > 29°C / 84°F): Very high risk of heat-related illnesses. Avoid outdoor exercise. Opt for indoor, air-conditioned environments.

Tips for Exercising Safely in Hot and Humid Conditions

1. Stay Informed: Check the WBT or WBGT before planning outdoor activities. Many weather apps and websites provide this information.
2. Hydrate Properly: Drink water regularly before, during, and after exercise. Include electrolytes to replace salts lost through sweat.
3. Adjust Your Routine: Exercise during cooler parts of the day, such as early morning or late evening. Shorten the duration and reduce the intensity of your workouts.
4. Dress Appropriately: Wear light-colored, loose-fitting, and moisture-wicking clothing. Use hats and sunglasses to protect against the sun.
5. Acclimate Gradually: Give your body time to adjust to the heat by gradually increasing the intensity and duration of your workouts over a period of 10-14 days.
6. Recognize the Signs of Heat Illness: Be aware of symptoms like dizziness, nausea, excessive sweating, confusion, and rapid heartbeat. If you experience any of these, stop exercising, seek shade, and cool down immediately.
7. Use Cooling Strategies: Utilize cooling towels, ice packs, and shaded areas to help lower your body temperature during breaks.

Conclusion

Wet bulb temperature is a critical factor in understanding the true heat stress on your body during exercise in hot and humid conditions. By staying informed about WBT and following safe exercise guidelines, you can protect yourself from heat-related illnesses and continue to enjoy your outdoor activities. Remember, when it comes to exercising in the heat, caution and preparation are key to staying safe and healthy.

At Princeton Sports and Family Medicine, P.C., our doctors specialize in sports medicine services, including exercise counseling to aid in your heat acclimation.

Call or click to book a session with our professionals at Princeton Sports and Family Medicine, P.C. We offer sports performance evaluations to stop problems before they start. Plan your visit today.

Author

Peter Wenger, MD Peter C. Wenger, MD, is an orthopedic and non-operative sports injury specialist at Princeton Sports and Family Medicine, P.C., in Lawrenceville, New Jersey. He is board certified in both family medicine and sports medicine. Dr. Wenger brings a unique approach to sports medicine care with his comprehensive understanding of family medicine, sports medicine, and surgery. As a multisport athlete himself, he understands a patient’s desire to safely return to their sport.