Safely Cycle in the Summer Heat

It’s summer in South Florida and that means it’s hot and humid.  While others may stop all outdoor activities that don’t include dipping into a body of water, that isn’t really an option for an avid cyclist.

Riding in the heat isn’t for the faint of heart and to do it safely, it is important to follow these tips.


Perhaps not surprisingly, this is at the top of the list. When the temperature climbs, your body keeps from overheating through evaporative cooling – in other words, sweating. When it is humid, however, this process is much less effective which causes the body to produce even more sweat. This leads to quick depletion of your bodies fluids.

Dr. Carolyn Kienstra, an expert at the University of Miami Sports Medicine Institute, explains that dehydration as little as two percent can affect your performance.

As (dehydration) gets more severe, it can affect your ability to think clearly.

“It also decreases your body’s ability to deliver nutrients to your cells and remove waste,” she says. “So prolonged dehydration can cause damage to your muscles and organs.”

In order to protect yourself from dehydration, you need to drink lots of water and not just during your ride. Ideally, you should start drinking water at least two hours before you start exercising – and after.  Even better, start drinking plenty of fluids the day before your ride. The American Council on Exercise recommends:

  • 17-20 ounces of fluid within the 2 hours before exercise
  • 7-10 ounces every 10-20 minutes during your workout
  • 16-24 ounces per pound of body weight lost during exercise

Kienstra adds that these are only guidelines. “Each individual’s sweat rate varies, and your own sweat rate can be variable from day to day based on internal and environmental factors,” she says.

As you sweat, your body also loses electrolytes, which you need. Athletes are at risk of hyponatremia, or low sodium in the blood, if they only replace the water they are losing.  Both dehydration and hyponatremia have similar symptoms, so it can sometimes be difficult to determine if you need more water or more electrolytes.

In general, athletes who develop vomiting or are urinating with increased frequency tend to be hyponatremic and need electrolytes, says Kienstra.  “Another way to assess your own fluid and electrolyte replacement is to weight yourself before and after exercise (in the same clothes, before you rehydrate),” she adds.  “You should weight mildly less after your exercise session.  If your weight is the same or higher than before exercise, this may be a sign that you are getting too much water without enough electrolytes.”

Stay cool

Another danger of cycling during the dog days of summer is heat-related illnesses. You can stay cool by hitting the road earlier in the day – the temperature at six in the morning can be ten to 15 degrees cooler than 3 in the afternoon.  Also, map your route to include lots of shaded areas if possible. Take lots of water breaks in those shaded areas.

You can also train your body to endure the heat more – or acclimatize.  Don’t start out by going on a three-hour ride in ninety degree weather.  Start with thirty minutes and let your body get used to the higher temperatures.

Even with acclimatization, some days it may be better to stay off the road. The heat index is a useful tool that can help determine those days.  Using the temperature and relative humidity, this chart advises how likely a heat related illness like heat exhaustion or heat stroke is to occur.

Dr. Kienstra explains that heat exhaustion develops when your body temperature compromises your ability to continue to exercise and that heat stoke occurs when your body temperature begins to compromise your thinking and brain function.  “Symptoms include confusion, headache, and irritability, and can progress to altered consciousness or seizures,” she says.  “On exceptionally hot days, it may be best to bike with a group so that you can watch each other for these symptoms.”

Dress for success

Wearing the right clothes can make a huge difference when you are cycling in the sun.  You want to wear tight clothes that wick away moisture.

Loose-fitting clothing actually doesn’t keep you cooler, as it traps air between the cloth and your skin.  This layer of air acts as insulation and reduces evaporative cooling. Wearing-form fitting shirts and bicycle shorts made of wicking material moves the sweat from your skin to the air where it can evaporate.

For cyclists, this type of clothing can also help to prevent painful “saddle sores,” which are abrasions on your buttocks that can turn into abscesses.

Saddle sores are more common as we sweat more, says Dr. Kienstra.  “There are many different creams to help prevent and treat them,” she advises.  “It is also a good idea to remove wet clothes as soon as you finish your ride and change into dry shorts for your post-ride meal or drive home.”


Natasha Bright is a contributing writer for the UMiami Health News blog. Her writing has also been featured on the Huffington Post and Scary Mommy websites.