Exercising Safely in the Heat: The Facts & Tips

Why Hot Weather Matters

• Heat is the leading weather‑related cause of death in the U.S., surpassing hurricanes and floods (WHO, n.d.).

• Each summer, about 600 people in the U.S. die of heat-related conditions and 65,000 visit emergency rooms due to heat illness (American Heart Association, 2019).

• Every year, around 9,000 U.S. high school athletes are treated for heat-related illness—teenagers are especially vulnerable (U.S. EPA, n.d.).

What Happens to Your Body

When you exercise in high heat and/or humidity:

• Sweating becomes less effective at cooling you, especially in humid conditions, putting you at risk of heat exhaustion or, worse, heat stroke (Johns Hopkins Medicine, n.d.).

• Core body temperature can climb between 98.6 °F and 104 °F during heat exhaustion, with symptoms like dizziness, nausea, fatigue, cramps, and headache (Wikipedia, n.d.-a).

• At the extreme, heat stroke can spike body temperature above 104 °F (40 °C), disrupt brain function, and be life-threatening if not treated promptly (Wikipedia, n.d.-b; Casa et al., 2015).

Acclimatize—Heat Training Works

• Gradual exposure to heat helps your body adapt: studies show that training at ~60 % VO₂max in 40 °C conditions for 9–12 days can boost endurance from ~48 min to 80 min (Périard et al., 2015).

• Experts recommend building up heat tolerance over 7–14 days, increasing workload slowly to allow your body to adjust without undue risk (OSHA, n.d.; Wikipedia, n.d.-c).

Smart-Planning Tips for Summer Workouts

• Exercise during the cooler part of the day: before 9 a.m. or after 7 p.m.; avoid activity if temps exceed ~90 °F or heat index crosses 103 °F (UC Davis Health, 2022).

• Hydrate proactively: water is best; aim for ~1 oz per kg of body weight and supplement with electrolytes if exercising hard or sweating heavily (Balmain Sports Medicine, n.d.).

• Dress right: choose lightweight, light-colored, breathable or moisture-wicking fabrics; use sunscreen, wear a hat and sunglasses (CDC, n.d.; The Guardian, 2022).

• Slow your pace: reduce intensity by ~15–20 % in oppressive heat; walk or bike instead of sprinting (Verywell Health, 2024).

• Use cooler activity alternatives: water-based routines like swimming, kayaking, or paddleboarding help regulate temperature while still offering a good workout (Verywell Health, 2024).

Recognizing and Responding to Heat Illness

Signs to watch for:

• Muscle cramps, fatigue, excessive thirst

• Dizziness, nausea, light-headedness, headache

• Profuse sweating, rapid heartbeat, low blood pressure, mental confusion (especially in heat stroke) (Wikipedia, n.d.-a)

What to do:

• Move to shade or an air-conditioned area; cool the body with damp towels or mist sprays

• Rehydrate with water or an electrolyte drink (if alert and able); avoid waiting until thirst hits (TIME, 2024)

• If you notice confusion, loss of consciousness, or worsening condition—seek immediate medical attention (TIME, 2024; Wikipedia, n.d.-b)

Bonus Tips to Beat the Heat

• Wet the skin before using a fan: fans alone may worsen dehydration above 90 °F; misting the skin first improves cooling significantly (Washington Post, 2025).

• Buddy up: exercising with someone means mutual monitoring for symptoms—especially important in heat (AP News, 2025).

• Listen to your body—heat speeds up fatigue, raises heart rate, and can overwhelm even experienced athletes. Pull back if needed and consider indoor alternatives or rest days (TIME, 2024; Vox, 2024).

Key Takeaways at a Glance

1. Plan smart - Workout early/late, avoid peak heat

2. Acclimatize gradually - Build heat tolerance over 1–2 weeks

3. Hydrate consistently - Water plus electrolytes if needed

4. Take it easy - Lower intensity, pace, and duration

5. Watch for warning signs - Start cooling and rehydrating ASAP

6. Use safer options - Indoor workouts or water-based activities

Sources

• American Heart Association. (2019). Exercise caution outdoors in the summer heat. https://www.heart.org/en/news/2019/07/24/exercise-caution-outdoors-in-the-summer-heat

• AP News. (2025). Summer heat safety tips. https://apnews.com/article/06ae07d432c11e768cfbd39489bcd01e

• Balmain Sports Medicine. (n.d.). Heat illness and exercise. https://balmainsportsmed.com.au/heat-illness-and-exercise/

• Casa, D. J., et al. (2015). National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses. Journal of Athletic Training, 50(9), 986–1000.

• Centers for Disease Control and Prevention. (n.d.). Heat & Athletes. https://www.cdc.gov/heat-health/risk-factors/heat-and-athletes.html

• Johns Hopkins Medicine. (n.d.). Exercise-Related Heat Exhaustion. https://www.hopkinsmedicine.org/health/conditions-and-diseases/exerciserelated-heat-exhaustion

• Occupational Safety and Health Administration. (n.d.). Heat Exposure. https://www.osha.gov/heat-exposure

• Périard, J. D., Racinais, S., & Sawka, M. N. (2015). Adaptations and mechanisms of human heat acclimation: Applications for competitive athletes and sports. Scandinavian Journal of Medicine & Science in Sports, 25(S1), 20–38.

• The Guardian. (2022). 10 ways to keep exercising in a heatwave. https://www.theguardian.com/lifeandstyle/2022/jun/15/10-ways-to-keep-exercising-in-a-heatwave

• TIME. (2024). How to help someone with heat exhaustion. https://time.com/7306526/heat-exhaustion-safety-how-to-help/

• UC Davis Health. (2022). 5 tips to exercise safely when it's hot outside. https://health.ucdavis.edu/blog/cultivating-health/5-tips-to-exercise-safely-when-its-hot-outside/2022/06

• U.S. Environmental Protection Agency. (n.d.). Heat and Teenage Athletes. https://www.epa.gov/children/heat-and-teenage-athletes

• Vox. (2024). Extreme heat and summer fitness. https://www.vox.com/even-better/421830/extreme-heat-summer-fun-exercise-mental-health-social-advice

• Verywell Health. (2024). How to exercise in hot weather. https://www.verywellhealth.com/how-to-exercise-in-hot-weather-11772189

• Washington Post. (2025). Fans and water in extreme heat. https://www.washingtonpost.com/wellness/2025/08/04/fans-heat-exhaustion/

• Wikipedia. (n.d.-a). Heat exhaustion. https://en.wikipedia.org/wiki/Heat_exhaustion

• Wikipedia. (n.d.-b). Heat stroke. https://en.wikipedia.org/wiki/Heat_stroke

• Wikipedia. (n.d.-c). Occupational heat stress. https://en.wikipedia.org/wiki/Occupational_heat_stress

• World Health Organization. (n.d.). Climate change, heat, and health. https://www.who.int/news-room/fact-sheets/detail/climate-change-heat-and-health