When riding this time of year, cyclists should not only be checking the temperature, but also the relative humidity levels, and looking at these levels on an hourly basis.  In parts of Canada and the United States located close to lakes, the weather websites will also provide an additional reading, that is known as the humidex level.  For those of you who aren’t familiar with humidex readings, it is a reading that tells you what the temperature actually feels like once you factor in the level of moisture (or humidity) in the air.  For example, on a very humid day the temperature may read 30 degrees Celsius but then depending on the relative humidity levels, the temperature could actually feel more like 38-39 degrees.  Therefore, if you are one who struggles with these conditions, be sure to check these levels, and be aware that humidity levels are generally higher in the morning, and lower as the day goes on, unless there are thunderstorms in the area, in which the relative humidity will stay high until the storm has passed through.


When you ride, your core body temperature will naturally rise and as a result you will sweat, this is the bodies cooling mechanism.  However, humidity prevents the sweat from evaporating, and cooling your body down.  So, the heat remains on and inside the body.  The next time you are riding in humid conditions, just feel your skin, and you will see the skin is still wet.  If the body heats up too much it will go into survival mode to maintain blood flow to the organs and to your skin.  Smaller riders, myself included, have a more difficult time in dissipating heat via sweat from their bodes quicker and more efficiently, while those who are smaller, with short limbs, overheat quicker, as they do not have the large surface area which allow the body to dissipate the heat.


In addition, another important message I give to all my coaching clients is, to watch how the bodies heart rate responds to the high temperatures and humidex levels.  Monitor this by taking your “standing pre-ride heart rate” if it is 5-10 beats higher before you begin your ride, this indicates the body is already working harder to cool itself, so a decrease in intensity is advised.  Also, constantly monitor your body while out on the road for breathing troubles.  Many cyclists in very high humidity conditions will struggle with breathing, and the breathing may become very shallow and laboured.  The reason for this, is the amount of moisture in the air is very high, and results in less oxygen getting through the breathing passages.  The air is so heavy with moisture, it will almost feel like you are in a pool of water, gasping for a full breath.  This is another sign your body is not tolerating the humidity very well, so slow down and back off your intensity.  Humidity can also produce an immune response causing an asthmatic like attack.  If you are prone to chest and bronchial aliments, be aware of this, and proceed on humid days with caution.


Below is a list of things you can do to help you continue to ride in these conditions

  • Wear a cycling hat underneath your helmet, to help keep the sun off the head.
  • Sun-sleeves worn on the arms to minimize the impact of the sun
  • Light mesh undershirt to wick away the sweat that pools on the bodies core.
  • Gradually expose yourself to the warmer temperatures, by building the time spent riding in these conditions.  It generally takes around 2 weeks to acclimatize to hot and humid conditions.
  • If high temperatures is your concern, ride early or late in the day, and choose shadier ride routes to cut down on the effects of the suns intensity.
  • Wear light coloured clothing, especially your jersey, as this will help reflect the sun and reduce overheating of the bodies core.
  • Carry sufficient fluids on very hot and humid days, with an extra bottle in your jersey and/or carry money to purchase additional fluids while out on long rides.
  • Take more frequent rest breaks on your rides, or if you are a cyclist who does not stop to eat or top up fluids, adapt by inserting 1 or 2 brief stops under a shaded area.
  • Heat and humidity can also cause you to feel sluggish, this doesn’t mean you are lacking the desire to ride, it’s your body’s physical response to the stressful environment.
  • Signs of heat exhaustion is fatigue, nausea, tingly skin, dizziness, headache and confusion.  Usually it will start with the nausea and then the tingly skin, and progress from there.  If you begin to feel these symptoms stop riding and seek shade, and electrolytes and cool the body with water.
  • Carry a cell phone with you, if you are cycling alone, in case you need assistance or you just can’t continue the ride.

After adapting many of the suggestions I have listed above, you may also want to consider preforming the very intense ride workouts such as intervals and tempo rides indoors on the trainer, on the extremely hot and humid days, as these rides are much harder to adjust the intensity, as in order to reap the benefits of these types of workouts, a certain level of intensity is required.   By doing this you will still be getting outside for the endurance and recovery rides, but you will be minimizing the negative impacts on the body by doing the higher intensity rides in and out of the extreme conditions.


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