Expert Voices: What You Need to Know About Exercising in Hot Weather

At LifeSpeak, we recognize that physical activity plays a crucial role in supporting overall wellbeing, including productivity, mental health, and resilience in the workplace. But as warmer weather arrives, many employees and organizations face an important question: how can we stay active safely when temperatures rise?

To help answer that, we turned to LifeSpeak expert and strength coach Tom Toth, who shares practical, evidence-based strategies for staying safe, preventing heat-related risks, and maintaining healthy exercise routines during the hotter months — whether employees are commuting by bike, participating in workplace wellness initiatives, or simply staying active outside of work.

Let’s talk about exercising in the blazing heat! I have started training more and more of my clients outside, and things like hydration and overheating in warmer weather can become serious concerns. It is absolutely worthwhile to try to maintain a workout routine through the hot months of the year, but precautions must be taken.

How does heat affect the active body?

When you exercise, your body burns extra calories that generate internal heat. This process raises your core temperature, and the body sheds this excess heat by radiating it away to the outside through the skin and sweating. The human body functions in a very limited temperature range: just a few degrees increase can cause serious damage to our internal organs and the brain. This is one reason why high fever is so dangerous; it is the same for exercising in hot weather.

Heat is only one of the two factors that can affect you: the other is humidity. High humidity makes it very difficult to cool yourself through sweating since your sweat can’t evaporate off your skin. Very humid weather can cause heat-related issues even if the temperature is moderate, especially if you are outside for an extended period.

In addition to the physical risks, it’s important to remember that heat can also contribute to added mental and emotional stress. Regular exercise has been shown to help reduce stress and support wellbeing, even when external conditions become more challenging.

“There is nothing to be gained by pushing yourself more.”

Signs you are affected by the heat

The early signs that you may be overheating are muscle cramps, headache, and higher-than-usual fatigue. You will probably also feel intensely thirsty as your body sheds water to try to cool you. If you are outdoors exercising and are starting to experience these symptoms, get inside and cool down. There is nothing to be gained by pushing yourself more.

If you continue to overheat, the next stage is heat exhaustion, when your core temperature actually starts to elevate. In addition to the above symptoms, you can also have unpleasant effects such as fainting, dizziness, rapid heartbeat, low blood pressure, and fast breathing. Definitely not something you want to experience!

The last stage in the unfortunate journey of overheating is heatstroke. This is an extremely serious condition that can be fatal if left untreated. With heat stroke, the body’s attempts to cool itself have failed. Core temperature rises as high as 41℃/106℉. Seizures, confusion, and coma are all possibilities. If you encounter someone who you suspect is having heatstroke, you must call 911 immediately, because the person requires medical intervention!

Another potential, though less dangerous issue is called “heat syncope”, which is dizziness or fainting associated with rapid positional changes while exercising in heat. When you start overheating while exercising, your blood pressure drops, resulting in less blood supply to the brain. Standing up suddenly can result in light-headedness or even fainting. While not a serious condition, keep this in mind, for example, if you are gardening or sitting down between rounds of tennis. Golfers can experience this while picking up the ball or while kneeling to get the lay of a putt. If you cross-train outside (doing CrossFit, for example), be aware of circuits that require you to lie down and then stand back up in rapid succession.

Steps you can take to avoid overheating while exercising outside

Build tolerance slowly

Like all environmental stresses, the body is able to build up a tolerance to exercising in warm temperatures. Current research shows that it takes about 10-14 sessions to build up your heat tolerance. Start with no more than 20 minutes a day, slowly increasing either your intensity or your time. Heat exhaustion can come on quickly, so I highly recommend exercising with a friend for added safety. Also, make sure you have your cell phone with you and carry plenty of liquids. For a quickest acclimatization, try to exercise every day for about a week.

“Heat exhaustion can come on quickly, so I highly recommend exercising with a friend for added safety.”

Take frequent breaks 

If you are engaging in a longer-duration activity like hiking, golf, or a bike ride, make sure you take hydrating breaks, preferably in shade. Letting your body cool down between bouts of movement will help prevent overheating. Use these breaks to assess how you’re feeling. Avoid the temptation to push ahead if you think you are starting to fatigue or overheat. I’m sure you want to get everything out of your paid-for round of golf, but collapsing on the 18th hole is not going to make for a memorable outing. Well, at least not for the reasons you would prefer…

In addition to rest and hydration, mindfulness practices like meditation can also support overall wellness during the summer months.

Avoid the hottest part of the day 

If it is very hot outside and you want to exercise, try to do it either early in the morning or in the evening. The hottest part of the day tends to be between 11 am and 4 pm, and mornings tend to be the coolest. This might be a good time to get into a “pre-work” routine for your walks, runs, or cycles. Humidity extends the heat considerably, especially if it is over 80%. Make sure you account for it.

Drink lots of liquids 

This tip might seem self-explanatory, but you have to understand that if you are prone to sweating and it is very hot and humid, you might be losing more than half a gallon (2 liters) of water an hour! This is far more than what most people generally carry with them. Staying hydrated is critical to avoid side effects from the heat. You can use this hydration calculator to help estimate how much water you should be drinking while exercising. Just remember that if you tend to sweat a lot, those numbers may even need to be higher. In this case, I highly recommend investing in a large-volume water carrier that you wear as a backpack or waist pack.

Another big concern with dehydration is the loss of electrolytes. Contrary to popular belief, sports drinks aren’t actually that high in electrolytes, and may not provide enough replacement for extensive outdoor sports activities in hot weather. This is a serious issue for endurance athletes. If you fall into this category, consult a competent endurance coach who has experience in hot weather events.

Preparation is key 

Simple things like checking the weather forecast, planning a route with plenty of break possibilities, buying a larger water container, and actively working on acclimatizing can all help avoid trouble. If you or someone you are with does suffer from a heat-related issue, try the following (remember to call 911 if you suspect heatstroke):

• Immediately move to a cooler area (or at least shade)
• Sit or lie down to help even out your blood pressure
• Keep drinking liquids slowly
• Remove unnecessary clothing, including shoes
• If available, cold compresses can help bring the body temperature down

Safe exercising!

Supporting safer summer wellness for your workforce

Encouraging physical activity is a valuable part of any corporate wellbeing program, but summer heat brings additional challenges that require awareness and preparation. By educating employees on how to build heat tolerance, stay hydrated, and recognize signs of overheating, organizations can foster a safer, healthier culture of wellness. Prioritizing safe exercise habits not only protects physical health but also supports mental clarity, energy levels, and overall job performance. As always, LifeSpeak is here to help organizations empower their people to make informed, healthy choices all year long.

Looking for ways to support employee wellness year-round?

LifeSpeak Holistic Wellness offers expert-led guidance on physical activity, mental health, nutrition, and safety, helping organizations empower employees to stay healthy, productive, and resilient in every season. See it in action. 

Tom Toth is a strength coach, movement specialist, and fitness educator based in Toronto, Canada. Since earning his degree from the University of Waterloo in 2003, Tom has achieved over 15 advanced certifications in areas including strength and conditioning, Olympic weightlifting, sports nutrition, and medical exercise. With a focus on injury recovery, chronic conditions, and elite athletic performance, Tom is dedicated to helping individuals move better, feel better, and live healthier lives. His extensive experience supports people of all fitness levels in building safe, sustainable exercise routines that enhance overall wellbeing.

Frequently Asked Questions

Q: What are the risks of exercising in hot weather?
Exercising in hot weather increases the risk of dehydration, heat exhaustion, heat syncope (fainting), and potentially life-threatening heatstroke. High humidity can make it harder for sweat to evaporate, further raising core body temperature.

Q: How can I safely start exercising in the heat?
Start slowly and allow your body to gradually build tolerance to hot conditions over 10–14 sessions. Begin with shorter workouts of 20 minutes or less, increase intensity or duration gradually, and always stay hydrated.

Q: When is the best time of day to exercise during hot weather?
The cooler parts of the day — early morning or late evening — are generally safest for exercising in the heat. Avoid peak heat hours between 11 a.m. and 4 p.m. whenever possible.

Q: How much water should I drink when exercising in hot weather?
Hydration needs depend on individual factors like sweating and activity level. In extreme heat and humidity, people may lose up to 2 liters of water per hour. It’s important to drink fluids regularly before, during, and after exercise.

Q: Can heatstroke happen quickly while exercising?
Yes. Heatstroke can develop rapidly if the body can’t effectively cool itself. Early warning signs like cramps, dizziness, and extreme fatigue should not be ignored. If heatstroke is suspected, seek immediate medical attention.

Q: What precautions should employers take to support employee wellness in hot weather?
Employers can encourage safe practices by educating employees on hydration, scheduling outdoor activities during cooler hours, providing shaded rest areas, and promoting gradual heat acclimatization.