Train with CORE: Testing your Cooling Strategies

Even when heat training and using pre-cooling strategies, it is still important that you cool yourself during training and competition. Most athletes are aware of some time-honoured ways of cooling – adequately hydrating, dousing the body with water, putting ice packs inside clothing, and choosing appropriate clothing are some of the popular strategies.

A first step in calculating hydration needs can be done with a sweat rate test, and then later refined by using CORE. Dousing with water and use of ice packs, while highly effective, is also dependent on their availability on the course. Choosing the clothing that keep you the coolest is a bit more complex, and is covered in detail below.

Choosing cool clothing

Choosing the coolest clothing is challenging, as numerous environmental factors come into play. Is the air humid or dry? Will you be exposed to a strong sun? Is there a breeze (either a natural wind, or strong airflow created by the athlete, such as in cycling)? Are there parts of a course that are particularly hot (such as long, slow climb on a south-facing slope, or a stretch with a light tailwind)? Will your race start cold and become hot through the day?

Evaporation of water from the skin is the fastest way to cool the body. But in very humid conditions, there is little evaporation, and thus little cooling. This might mean that a different type of clothing works better in humid conditions than in dry air. Likewise, there may be times when you want to wear long sleeves to keep the sun off your skin, and other times leave your skin exposed to better let sweat evaporate.

The specific qualities of the fabric can also be relevant. For example, a moisture-wicking fabric will draw sweat away from the skin. However, there may be times when it is more beneficial to leave sweat at the skin so it can evaporate and cool you.

Keeping the skin cool

An important part of performing in the heat is keeping the skin cool. A greater temperature difference between core temp and skin temp means less performance decline when core temps become elevated. In devising cooling strategies, consider how to keep your skin cool. Evaporative sweat cooling? Dousing with water? Shading from the sun?

Collecting data with your CORE

With these considerations in mind, you’re now ready to test a couple of cooling strategies. A good one to start with is comparing two clothing choices (perhaps two tri suits, or two cycling jerseys, or two running singlets).

You’ll test these articles by repeating a simple workout on different days, each time wearing a different clothing choice. It’s important to be methodical about keeping every other part of the workout the same, and as close to race conditions as possible. Which means:

  • Do the workouts in weather similar to what you expect on race day. Air temperature, humidity level, sun exposure, wind conditions and time of day should all be the very similar each time you do a clothing test.
  • Another important criterion is your pre-workout hydration level. Checking your urine colour and your body weight are good ways of approximating hydration level. They should be kept constant for each workout.
  • Your starting core temp should be the same at the start of each workout.

Workout 1

Wear the first article of clothing you want to test. After a warmup, do a 45–60 minute steady-state endurance ride or run. Keep your heart rate constant, and do not take calories or fluids during the workout. Avoid using other cooling measures, such as dousing your body with water.

Monitor your core temp throughout the workout, and then load the data file into training software after the workout.

Workout 2

On a different day, wear the next article of clothing you want to test. Repeat Workout 1, keeping your heart rate the same. Monitor your core temp throughout the workout, and then load the data file into training software after the workout. Can you see a difference between your core temp in the two workouts?

Follow up workouts

It is a good idea to do several tests with each clothing item. It’s possible the data may be a bit noisy, especially if there were differences in the weather or in your hydration level. But with a few trials, you should be able to identify if there’s a clear difference in clothing items or not.

An additional set of tests involves dousing your body with water at a predetermined frequency, repeating that protocol for each article of clothing you are testing. It is possible that one item does better with water dousing than it does without.