17. HOW TO REGULATE TRAINING INTENSITY IN THE HEAT?

Photo by Markus Spiske on Unsplash

In the last post, we saw that pro road cyclists’ maximal mean power outputs decrease when riding at very high environmental temperatures: >25°C for women and >30°C for men. So women tolerate worse high temperatures probably due to their lower sweat rates and higher % of fat mass compared to men.

Performance differences often imply also changes in ventilatory/lactate thresholds, and so in training zones. So, also power output at physiological thresholds and power training zones could move downward when riding in a hot compared to a temperate environment. This should make us think about the best method to regulate training intensity in the heat.

Does power output at thresholds change when training in the heat? And what about heart rate at thresholds?

So, how to regulate training intensity in the heat?

A study published by Ed Maunder and Colleagues from Auckland University of Technology on International Journal of Sport Physiology and Performance in 2021 tried to answer these questions. (1)

---

WHAT DID THEY DO?

• They recruited 16 trained cyclists and triathletes (mean VO2max: 57)

• At the lab of Auckland University of Technology, they have an environmental chamber, that is a room where temperature and humidity can be manually set and adjusted as you prefer.

• In this environmental chamber, the participants performed an incremental exercise test to establish power output and heart rate at the first (VT1) and second (VT2) ventilatory thresholds, in two different days and environmental conditions:

  • HEAT: 35°C

  • CONTROL (CON): 18°C

  In both conditions, rate of humidity (rH) was the same: 60%.

---

WHAT DID THEY FOUND?