Heat adaptation is a beneficial but limited tool that should not compromise the quality of your key sessions; it is preferable to reserve heat exposure for easy runs and prioritize cooler conditions for high-intensity training.

noli's read

Science supports the idea that heat training induces physiological adaptations (such as increased plasma volume and earlier onset of sweating), documented by meta-analyses such as that by Périard et al. in 'Sports Medicine'. However, this literature also highlights that these benefits are transient and lost rapidly after exposure ceases. It is widely accepted in observational evidence and expert recommendations that training in extreme heat decreases the ability to maintain high intensity, thus risking the degradation of the specific quality of interval sessions. The notion that heat replaces altitude is widely considered an oversimplification, as the mechanisms for responding to hypoxia differ fundamentally from thermoregulation. The r/AdvancedRunning community converges on a pragmatic consensus: do not sacrifice overall performance for thermal adaptation that is only necessary if the target race is potentially hot. In summary, the trade-off between effort and adaptation is real, and the risk of overtraining or excessive fatigue is often underestimated by runners.

the sources

1. 1Périard JD, Eijsvogels TMH, Daanen HAM 2021
2. 2Tyler CJ, Reeve T, Hodges GJ, Cheung SS 2016
3. 3Racinais S, Alonso JM, Coutts AJ, et al. 2015
4. 4r/AdvancedRunning