As it warms up it is good to know a little bit about how your body cools itself and the way to maximise the cooling effect and allow you to get the most from your training.
The body exchanges heat with the environment in 4 ways. Conduction, Radiation, Convection and via the cooling properties of sweat. Air being a poor conductor means conduction is negligible and can be ignored, radiation is the body’s primary form of heat loss when the air temperature is cooler than the body but when it is a similar temperature +- it is negligible. Convection helps with heat transfer and is most significant when the air is moving; on a strongly windy day the convection heating effect (if air is 37C and above can cancel out the cooling from sweat.
Sweat cools your body due to the physical properties of water which, when it evaporates, requires energy from the environment to allow the change of state (from liquid to gas) (Latent heat of vapourisation).
Sweat is the ONLY cooling mechanism available to the body once the air temperature exceeds the body’s (37C).
In low humidity conditions (encourages more evaporation) sweat can cool a 38C surface to 20C so sweat can actually make your skin feel cold if the air is dry. In higher humidity the results are less strong but still significant.
For us, as residents of a country, where the temperature is high and we are relying on sweat to keep us cool it is essential to consider a few things
- In hot weather the sweating water requirement is significant. In air of 38C you will need at least 700ml of water per hour for sweat. This figure will be higher if you exercise and higher if it is windy. At Bootcamp we expect you to bring at least 1.5litres of water to a summer session.
- Sweat that drips off your body does not cool you. It is wasted. That is why wicking undergarments work. They force the sweat you produce to evaporate and cool you. Consider some 2XUs from Go Sport.
- There is no real need for sports “isotonic” drinks unless training exposed to the heat for 3-4 hours. Mostly they are just sugar.
- Drink cool water. It helps cool you down
- Pre hydrate – on the day of training stay well hydrated throughout the day. That way your reserves are well stocked up for when you need them
- If extremely hot then pour some water on your head. It can boost the cooling impact (especially if the water is cool)
A key element in staying cool in the hot weather is acclimatisation. People exposed to heat become better adapted at dealing with it and in fact produce more sweat than someone new to the environment. If new to training outdoors take this into account.
