Heat Training

MUSINGS FROM A COACH - 8 APRIL '25

I’ve never been a fan of exercise “fads” or “shortcuts” to training or physical adaptations. While cold plunging (getting in cold water) may have some “potential” physiological benefits, I suggest focusing our attention on heat training and its potential to improve our performance.

What is it? 

Heat training creates an environment that either during, after, or even outside of training, causes the body’s internal temperature to rise, leading to physiological changes.

What is the goal? 

We are seeking to promote a physiological adaptation to heat that can lead to improved endurance performance in hot conditions and, as recently proven, in normal conditions. Our primary objective is to achieve a lower body temperature at the same intensity.

• Normal body temp: 37ºC (98.6ºF)

• Functional Range: 35º - 41ºC (95-105.8ºF)

• >39.5ºC (103.1ºF) Negatively impacts performance

And there are additional benefits as well.

What does it do to us physiologically? 

When we follow a heat training plan effectively, our body undergoes adaptations that enable it to sweat earlier and more profusely. This heightened sweating enhances its evaporative cooling capabilities, effectively lowering skin temperature. Additionally, there’s an increase in plasma volume, which immediately dilutes the red blood cells (hematocrit) in our blood. In response, our body compensates by producing more red blood cells, thereby expanding our oxygen-carrying capacity. This results in improved endurance, stamina, and aerobic performance.

Physiological adaptations of heat training:

• Lower body and skin temperature

• Earlier and increased sweat rate

• Reduced electrolyte loss

• Reduction of heart rate 

• Expansion of plasma volume

• Expansion of body water

• Reduction of lactate accumulation during submaximal exercise 

How do we implement it?

For simplicity, let's break implementation down into two categories: Active and Passive.

• Active heat training is exercising in a hot environment or wearing apparel during exercise that increases our internal body temp (~45-60min+).

• Passive heat training is typically training first, then quickly following with time in a sauna or hot tub (~30min+). Passive heat training can also be done outside of training, but the time recommendations change (~45min+).

Two methods of implementing are: a 2 week adaption period or a maintenance period.

• Adaptation Period: 2 weeks leading into an event, you want to shoot for 12 sessions out of the 14 days (1 session per day).

• Maintenance Period: Outside of 3 weeks, then we shoot for 3+ sessions out of 7 days.

What does it look like?

• 60+ min. of exercise outdoors in ambient heat (80+ F)

• 60+ min. of exercise outdoors overdressed (pants, sleeves)

• 60+ min. of exercise indoors without fan/AC

• 30+ min. sauna (160-180 F) after exercise (enter <10’ after)

• 30+ min. hot bath (104-108 F) after exercise (enter <10’ after)

• 45+ min. sauna (160-180 F) removed from exercise

• 45+ min. hot bath (104-108 F) removed from exercise

Heat exposure is a stressor, so adjust your training accordingly. Begin an adaptation period 2 weeks prior or a maintenance period in advance (≥3 weeks) and maintain this adjustment. Choose the approach that best suits your training and travel schedule and monitor your exercise sessions using the Rate of Perceived Exertion (RPE) or heart rate (HR). Avoid inducing strain beyond what would be typically done. If you use a sauna, hot bath, or any other heat mode after training, plan to refuel and hydrate before starting. Heat training can increase body water, leading to a slight increase in body weight. However, this is a small price to pay! ;)