When spring and summer hits, many people run earlier or later in the day to avoid the heat.
Some are not so lucky to have such a flexible schedule, for many it is becoming more important to pay closer attention to the thermostat.
When it comes to acclimatizing to the heat, sweating is the name of the game. This is a skill the body naturally has, yet through technique and training, it can be improved.
Where does heat come from?
1) Metabolic heat from breaking down fuel during exercise
2) Environmental heat from the sun.
In us humans, the majority of energy generated to run is unfortunately released as heat instead of actually moving us. Not being able to dissipate this heat is a major contributor to fatigue.
How do we cool the body?
Primarily through sweat and respiration. There is not much we can do to improve respiratory heat loss. But sweating can be improved. Water requires energy to evaporate off of our skin. Heat from our body is absorbed by the water and it evaporates, cooling us in the process.
How can we improve our thermoregulation?
This mainly comes down to sweating better.
Exfoliation is the process of removing the outer layer of dead skin cells. This may help keep your skin clean and allow sweat glands to function optimally.
You can also make sure you are sweating well by not using product that reduces the ability of your body to produce sweat or let it evaporate off of your skin. Scape Sunscreen was designed to allow your body to sweat better than other sunscreens which may interfere with evaporation. Underarm antiperspirants worn during a run in the heat may also not allow the body to sweat like it should, since many of them literally close up underarm glands.
Finally, perhaps the best but most difficult method of improving your ability to keep cool in the heat, is to train your body to sweat better.
Heat acclimatization fully develops after 7 to 14 days after training in heat. Any method to induce an excessive rise in body temperature during exercise will suffice. Methods range from training in the highest heat of the day, doing hot yoga, and/or wearing layers of clothing while training.
Heat acclimatization can be fully retained for about a week after the training ends and can last in some degree for up to a month.
The changes that occur during acclimatization are heart rate, body temperature, metabolic rate, rate of muscle and blood lactate accumulation, and sweat salt all decrease during exercise. The sweating rate increases due to the increased secretory capacity the sweat glands develop during training.
How can we use this to our advantage?
Training in the heat is similar to training at elevation. You will never be as fast as you are on a cool sea level run, but the body adaptations from heat or elevation will make you a stronger runner in more favorable racing conditions.
Performing hot yoga, hanging out in a steam room, or doing some training while wearing extra clothing are all ways to warm your body up to "train" its ability to cool you.
Another method is to "Train Hot and Race Cool", where you perform easy and low effort runs in the hot periods of the day to acclimatize better. If you can, it's very important to do your key workouts, where pace matters, in the morning so you can still train to your best ability. Yes when race day comes, you'll have the improved thermoregulation from doing the very warm runs, but it will be benefiting you at a cooler morning race!