Our systems are incredibly adaptable, but they need time to adapt. There are strategies to achieve heat adaptation. Studies from Racinais et al., Houmard et al., and Santiago et al. provide guidance on using a two-three-week acclimatization phase to bring all the benefits to bear to get the most out of training or competing in the heat. Racinais et al., a consensus paper on this topic, is worth reviewing.

Traditional strategies recommend training in the heat at 40-60% VO₂max for 60-100 minutes a day for 10+ days for acclimatization. This is quite the time commitment within the training period. But Houmard et al. used sessions of 75% VO₂max for 30-35 minutes to achieve equal levels of heat adaptation as compared to sessions of 50% VO₂max for 60 minutes.

The time frame for adaptation will vary based on the status going into the acclimatization training. Trained subjects adapt faster than untrained individuals, but continuing the training for two weeks can stabilize the adaptations.

Santiago et al, noted that benefits of heat adaptation “include reduced oxygen uptake at a given power output, muscle glycogen sparing, reduced blood lactate at a given power output, increased skeletal muscle force generation, plasma volume expansion, improved myocardial efficiency, and increased ventricular compliance.” And the study found that in addition to “lower blood lactate levels measured after heat acclimation in both environments (cool and hot), we are the first to report that the threshold at which blood lactate levels begin to rise also is delayed by heat acclimation.”

This delay in lactate levels rising and lower lactate levels is excellent news for those following the AGT style of A+A training.