The ergogenic effect of heat training for performance in cool conditions remains unresolved

Comment on 'Rebuttal by Lars Nybo and Carsten Lundby' DOI: 10.1113/JP271668 . Comment published online only as‘supporting information’ to the original debate. The ergogenic effect of heat acclimatization (HA) training for performance in cool conditions is yet to be consistently evidenced in studies (Nybo and Lundby 2015), which noticeably, also suffer a number of methodological inconsistencies and limitations. We highlight a key methodological consideration suggested by Minson and Cotter (2015) that may account for equivocal findings- the use of HA as either a supplemental (Lorenzo et al. 2010) or replacement (Karlsen et al. 2015; Keiser et al. 2015) training tool. From evidence to date, the former approach may be considered the most attractive for athletes living in cool conditions since it allows the maintenance of high-quality mechanical/physical training stimulus (i.e. intensity/duration parameters) in cool conditions. Perhaps the potential adaptations associated with low/moderate-intensity replacement HA on a whole cannot overcome an insufficient mechanical training stimulus for highly-trained athletes subsequently performing in cool conditions? This is similar to the limitations upon training quality during chronic high-altitude exposure (live-high train-high) (Millet et al. 2010).