Exercising in the Heat: Your Guide to Summer Workouts

Fact checked by Olga Sadouskaya, MD
Clinical Pharmacologist, Chief Medical Officer

When we think of the summertime, lots of us imagine all the different fun activities that you can do during this season: going to the beach, hosting a backyard barbeque, dancing at a festival, and exercising in warm weather.

There are plenty of sporty activities that you can participate in during the summer, and many of them are hard to enjoy during other times of the year. But have you ever wondered if it’s safe to exercise in the heat? What can you do to stay safe when you exercise during the summer?

Keep reading to learn more about exercising in the heat, its risks, and how to stay safe during your summer workouts.

How much does body temperature rise during exercise?

When you exercise, your body movements produce metabolic energy that is released as heat. Some of this heat is also stored inside your body, which can increase your core temperature. Research has found that heat production during strenuous exercise can even exceed 1,000 watts.

When your body senses this increase in temperature, it naturally regulates your body temperature to keep it within normal range. It does this by making you sweat and increasing blood flow to your skin. Warm temperatures can make it harder for the extra heat to dissipate from your body, which can increase your risk of certain heat-related workout injuries. In addition to the heat, moist and humid weather also makes it more difficult for sweat to evaporate and heat to dissipate.

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Just how much body temperature rises during exercise will depend on the environmental conditions and the intensity of your workout. If you’re exercising at 80–90 percent of your aerobic capacity and under conditions where heat can’t dissipate well, your core body temperature could rise by roughly 2 degrees Fahrenheit every 5 to 8 minutes.

Heat-related workout injuries and illness

Extreme temperatures — both hot and cold — can lead to health problems and injuries. Keep in mind that anyone can experience a heat-related workout injury; however, certain risk factors can make heat-related injuries more likely. Some of the risk factors include:

  • Direct sun exposure
  • Poor fitness level
  • Bad acclimatization to a hot environment
  • Dehydration
  • Age (children and seniors respond worse to heat than other age groups)
  • Obesity
  • Taking certain medications
  • Having an underlying medical condition
  • Fever

Heat exhaustion

Exercise-related heat exhaustion is a heat-related injury that happens when your core body temperature is higher than normal during a workout. If your body can’t lower your temperature, it could rise between 101 F (38.3 C) and 104 F (40 C). Common symptoms of heat exhaustion include:

  • Rapid heartbeat
  • Rapid breathing
  • Dizziness
  • Weakness
  • Fatigue
  • Excessive thirst
  • Headache
  • Nausea
  • Vomiting
  • Fainting
  • Confusion
  • Low blood pressure

Unlike more severe heat-related injuries, heat exhaustion shouldn’t cause serious neurological problems, such as delirium or coma.

Men exercising on a beach in the heat

Heat cramps

Heat-related muscle cramps are painful muscle contractions that happen while exercising in hot weather. Muscle cramps feel like painful spasms, and they commonly affect the legs, arms, and stomach muscles. The affected muscles often feel firm or hard to the touch.

Exercise-related muscle cramps typically occur when you don’t replace water and electrolytes during strenuous physical activity, which can cause abnormalities in your muscle contractions.

Heat syncope

Syncope occurs when you feel lightheaded or faint. During a heat-related syncope, you may feel lightheaded, fatigued, or dizzy during or immediately after physical activity or standing for too long in warm temperatures. In some cases, you may even faint and lose consciousness temporarily.

Heat syncope is more common shortly after starting a new physical activity, since your body hasn’t had time to adjust properly. It’s also more common among athletes who are returning to their workout routines after being injured. Certain medications, such as diuretics, which make you urinate more often, can also increase your risk of heat syncope. If left untreated, syncope can progress to heat stroke.

Heat stroke

Heat stroke is a severe heat-related injury that can be life threatening if it isn’t treated quickly. This condition occurs when your core body temperature rises above 104 F (40 C), and it represents an acute medical emergency since your body is unable to lower its temperature on its own.

As we mentioned above, heat stroke can occur as a progression of heat syncope, but it can also happen in people without a previous heat-related injury. Symptoms of heat stroke can include:

  • Dizziness
  • Nausea
  • Vomiting
  • Fatigue
  • Confusion
  • Disorientation
  • Irritability
  • Seizures
  • Abnormal heart rhythm
  • Visual alterations
  • Unconsciousness
  • Coma

Summer workout safety tips

Follow these simple tips to stay safe when exercising in the heat.

Choose workout time wisely

If you’re planning to work out during the summer, it’s always a good idea to watch the weather forecast and heat index so you can avoid high temperatures and humidity. The hottest temperatures of the day usually occur between 11:00 a.m. and 3:00 p.m. If you are used to working out during these hours, it may be a good idea to switch your exercise times during the summer. Early morning and evening hours will probably be much cooler and safer for a summer workout.

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If you can’t exercise at a different time, watch out for hot weather days so you can move your workout indoors or exercise in the shade. Avoiding direct sun exposure is also a great way to prevent heat-related exercise injuries. You could also try swimming during the summer to stay active while avoiding the heat.

Stay hydrated

Dehydration can happen quickly during a summer workout, and it plays a major role in heat-related injuries. To stay hydrated, drink plenty of fluids before, during, and after your exercise routine without waiting until you feel thirsty.

A man drinking water on a hike in the heat

You can try drinking 16–24 ounces of water before working out; consider an electrolyte drink if you’re planning an intense workout. These drinks help replace electrolytes such as sodium, potassium, and chloride, which are lost when your body sweats a lot.

Use sunscreen

Sunscreen protects your body from sunburn, which can worsen dehydration and decrease your body’s ability to cool itself. Sunscreen also helps lower your risk of developing skin cancer. You should always wear sunscreen with an SPF of at least 30 if you’re planning to be out in the sun, and you should reapply your sunscreen periodically.

Wear light clothes made of natural fabrics

When you work out, clothes made of synthetic fabrics can trap your body heat and make it harder for it to dissipate, which can increase your body temperature even higher. 

Choose loose, ventilated, lightweight clothes for your summer workouts, and if possible, add a hat with a wide brim to your outfit.

Additionally, light-colored fabrics can help reflect sunlight and keep your body temperature down, while dark fabrics will absorb sunlight and make it more difficult for heat to dissipate.

Pay attention to your body’s signals

We all have different fitness levels and tolerance to the weather, so it’s very important to pay attention to your body’s signals during your summer workout. Some people may be able to exercise longer, even in warm temperatures, while others will need to keep their workout indoors or only exercise for a short period of time. That’s okay! Keep in mind that your priority should always be to stay healthy and safe, regardless of the weather.

If you develop any symptoms of heat-related injury during your summer workout, it’s important to stop what you’re doing, lower your body temperature, and rehydrate yourself. When possible, you should also have someone stay with you to help you monitor your symptoms in case you require assistance.

In cases of heat exhaustion or heat stroke, you should remove as much clothing as possible to facilitate heat dissipation. 

The most effective way to lower your body temperature is to take a cold bath. 

You can also use fans, ice packs, or water sprays to cool down.

Be sure to call emergency services if you or someone near you is exhibiting signs of heat stroke, since this is a medical emergency that requires urgent care. You should also call emergency services if you don’t feel better within 20 minutes.

Summer workout plan: An example by WeatherWell

Your perfect summer workout will largely depend on your fitness level and the environmental conditions around you. It’s a good idea to start with a lighter workout if you’re getting acclimated to the heat or trying to improve your fitness. You can progressively increase the intensity and duration of your workouts over the course of a few days or weeks.

You can try a slow-paced activity, such as yoga or light weight lifting, to tone your muscles without straining your body. Other good ideas for summer workouts include low-impact activities such as walking, swimming, short circuit training, water sports, volleyball, and cycling.

It’s best to stop your workout if you’re feeling symptoms of a heat injury. Summer is a great time to improve your fitness, and following these tips will make it easier for you to enjoy a great summer workout while staying healthy and safe.

July 21, 2022