## 3 Whole-Body Washdown
Arrows signify a reduction or no change in sweat electrolyte concentration following HA. From the [PERSON] et al. (2021 and 2022) study, participants performed both an HAz and HA protocol, resulting in two separate time points of adaptation measurements: post-HAz and post-HAz + HA. The HAz protocol involved self-directed summer training for approximately 109 \(\pm\) 9 days. Following this, participants completed a 5-day HA protocol. Significant reductions were noted in Na\({}^{+}\) and Cl\({}^{-}\) post-HAz + HA compared to both baseline and post-HAz measurements, demonstrating adaptations from HA [42]. However, no significant differences were seen between the baseline and post-HAz, suggesting HAz may not be a strong enough stimulus by itself to induce sweat electrolyte adaptation. Indeed, the HAz protocol involved participants performing self-directed summer training and average WBGT temperatures were -22.5 \({}^{\circ}\)C, thus potentially not being a strong enough stimulus [42]. From the same overall study, intermittent heat training (IHT) was implemented to combat decay and maintain physiological adaptations following HAz + HA [43]. Participants completed 0, 1, or 2 days of heat training per week for a total of 8 weeks, with adaptations being measured after 4 and 8 weeks. Interestingly, there was no sweat electrolyte concentration maintenance for Na\({}^{+}\) or Cl\({}^{-}\) with both IHT protocols [43]. K\({}^{+}\) was maintained throughout the 8 weeks; however, this conservation did not seem to be because of the IHT as even the control group experienced the same K\({}^{+}\) maintenance. At the week 4 and 8 time points, Na\({}^{+}\) and Cl\({}^{-}\) concentrations were higher compared to post-HAz + HA across all conditions. These findings suggest that IHT may not be effective in maintaining sweat electrolyte adaptations, but K\({}^{+}\) may be maintained after HA even without IHT [43]. [PERSON] et al. (1987) found no adaptations following a summer HAz protocol, for both sweat and plasma electrolyte concentrations [44]. Highly trained distance runners trained during the summer months in the northeastern United States for 14.5 weeks. Although no adaptations were noticed, this was likely due to the moderate temperature conditions not being hot enough to induce appropriate stimulus for adaptation to occur. Indeed, only 3 days of the 14.5 weeks HAz had a maximum daily temperature above 30.3 \({}^{\circ}\)C, with most of the mean maximum temperatures ranging between -20 and 30 \({}^{\circ}\)C. Most HA research utilizes temperatures above 35 \({}^{\circ}\)C in order to induce adequate stimulus for adaptation [64]. Extended time with an internal body temperature above 38.5 \({}^{\circ}\)C is suggested to be a factor in inducing physiological adaptations for performance in the heat [64]. This may partly explain why no physiological adaptations, including sweat and plasma electrolyte concentrations, were seen in this study. In contrast, [PERSON] et al. (1988) saw a decreased concentration of sweat Na\({}^{+}\) following a 10-day HA protocol, but no significant decrease in K\({}^{+}\)[45]. The sweat electrolyte adaptation is likely linked to the improved core temperature that the control group experienced from the HA protocol.