Table 2.

Factors to consider when determining the protocol of heat acclimation.

Heat acclimation (HA) modes		Exercise in the heat	HWI	HWI after exercise	Passive hot air	Passive hot air after exercise
Considerations
	Adaptive potential	Likely largest stimulus for adaptation (for complexity, systems, impulse)	Large thermal stimulus		Difficult to achieve air temperature sufficient to drive Tc strongly (unless sauna), but warm Tsk may aid cardiovascular effects
		Validity in elite, i.e., already adapted?	Little evidence	Prolong stimulus or alter adaptive stimulus from preceding exercise?		Prolong stimulus or alter adaptive stimulus from preceding exercise?
	Quality and quantity of regular training	Absolute intensity of training reduced beyond first ~15–20 minutes. Factor in to total training volume	Likely little effect due to passive nature	Maintain regular training	Likely little effect due to passive nature	Can maintain regular training
		Vs. regular training? When/how to periodise?	Effect on training quality when engaging in HA and training on same day?	Effect on quality of subsequent training? Impact previous adaptive stimulus?	Effect on training quality when engaging in HA and training on same day?	Effect on quality of subsequent training? Impact previous adaptive stimulus?
	Time efficiency	Large heat production	Strong conduction of heat so potent thermal stimulus	Can combine with regular training	Weaker thermal stimulus (unless sauna), so increased duration required	Can combine with regular training
		Vs. regular training? Especially considering likely financial and other burdens (e.g., environmental)		Relative benefit vs. other recovery modes (e.g., sleep/nutrition/cold)		Relative benefit vs. other recovery modes (e.g., sleep/nutrition/cold)
	Recovery	May cause muscular fatigue	Could promote muscle recovery	Could promote muscle recovery	Little evidence	Potential for impaired glycogen resynthesis
				Alter adaptive stimulus from preceding exercise?	Potential for impaired glycogen resynthesis	Alter adaptive stimulus from preceding exercise?

The considerations a practitioner must take into account when designing and implementing a heat acclimation program are highlighted with respect to the most common modes of heat acclimation. The first row (color designation) corresponds to the evidence available to suggest implementing the mode of heat acclimation, in the context of the given training/athletic consideration. Black, gray, and white correspond to highly useful, moderately useful, or not useful, respectively. The assessments are made based on the information in the rows below, and the evidence presented in Figure 4 and throughout the review. The first row highlights the positive and/or negative elements of the given heat acclimation mode for the given consideration, respectively. The second row provides notes for future research considerations. The table is intended as a brief practical guide and summary of evidence, as some caveats exist: i) The importance of the above adaptations are based on the physical requirements of the sport and the physiological adaptations that would enhance performance within hot and humid environments; ii) the training foci during this period may likely change and the individual situation must be considered; and iii) the effect each mode of heat acclimation has on the training foci (e.g., exercise in the heat impairing quality of the following training session) has not currently been investigated and the current perspectives are based on preliminary understandings of these modes; v) the mode of heat acclimation used will depend on factors additional to those mentioned above (e.g., time, equipment) [170], but mentioned throughout the review. Tc, core temperature.