06/23/2025
Tips from Coach Bob
Determining if it is Safe to Run in the Heat
Heat increases fatigue and metabolic strain, decreases running performance, and increases the risk of injury. The body dissipates heat by increasing blood flow to capillaries in the skin where heat radiates into the atmosphere. Sweating removes heat through ev***ration from the skin by turning the water in sweat into water v***r. Humidity decreases the ability of the water in sweat to ev***rate, and heat remains in the body, which increases the risk of heat illness.
The Heat Index Chart
The Heat Index incorporates both Temperature and Relative Humidity to provide a value of how hot it feels to the human body (see chart below), and it indicates the likelihood of heat disorders with prolonged exposures and/or strenuous activities. For an example, 86-degrees F in Maimi with 80% humidity can be more dangerous than 86-degrees F Phoenix with 40% humidity.
Determining if it is Safe to Run
Check the hourly forecast for temperature and relative humidity to see what the Heat Index will be at the end of the run, but keep in mind that the Heat Index is not a perfect tool. The values are for temperatures in the shade, and exposure to full sunshine can increase the values by as much as 15 degrees F. Also consider that a runner dealing with the first heat wave of the summer may not have acclimatized to heat, and they are more likely to have an issue with heat illness than later in the summer. Heat acclimatization takes at least 14 days.
If the decision is made to run, run at a slower pace with a sports bottle and wear lightweight, light-colored clothing. Plan a course with shade or get off the roads completely with a trail run. Pavement radiates heat back at runners making it feel hotter. Consider running a shorter loop multiple times with a single aid station with a cooler, which allows runners to:
⚫ Keep additional sports bottles cold
⚫ Use bandana ice packs under a hat or on the back of the neck
⚫ Towel off frequently to help to improve sweat ev***ration
Respect the Heat and Hydrate well before, during, and post-run!