Of note, from the first study I included:
" Performance in cool environment
The observation of enhanced aerobic performance in cool conditions by Lorenzo et al. (2010) supports previous findings that heat acclimation improves V˙O2max
in untrained (13%) and unfit (23%) individuals in cool conditions (Shvartz et al., 1977). It also reinforces the 32% increase in run time to exhaustion noted in fit individuals by Scoon et al. (2007) after acclimation via post‐exercise sauna bathing, and the observation that swimmers training in a tropical climate (30 °C, 80% RH) in 30 °C water had greater improvements (10%) in performance when returning to a temperate environment (27.1 °C pool water) than swimmers who kept training in a temperate environment (Hue et al., 2007). Other studies have also observed that team‐sport athletes participating in preseason (Racinais et al., 2014), in‐season (Buchheit et al., 2011), and off‐season (heat and altitude; Buchheit et al., 2013) training camps in the heat (∼34 °C) improve performance by 7% and 44% (Yo‐Yo Intermittent Recovery test level 1 and 2, respectively) in temperate conditions (∼22 °C). The mechanisms modulating the transfer between hot and cool conditions could be linked to a variety of ergogenic responses, with cardiovascular/thermoregulatory (Lorenzo et al., 2010) and cellular (Bruchim et al., 2014) adaptations. As recently highlighted by Corbett et al. (2014), heat acclimation may provide a stimulus for improving performance in nonthermally challenging environments via improvements in V˙O2max, lactate threshold, and economy. Interestingly, it has also been suggested that heat acclimation may serve to preserve or enhance performance at altitude (White et al., 2014). The purported pathways for such a response include plasma volume expansion, improved cardiac efficiency, and involve the up‐regulation of hypoxia‐inducible factor‐1 in boosting oxygen delivery. Currently, however, additional research with well‐designed protocols (e.g., sufficient participants and control groups) is required to elucidate the mechanisms associated with improvements in performance at altitude and in cool conditions, as well as fully substantiate the ergogenic benefits of heat acclimation on performance in these environments. "