4.1. Dehydration
dehydration, BM loss, PV loss
DEHYDRATION, HEAT
At a 2% BM loss, PV loss was not significantly different under passive versus active heat stress; however, at a 3% BM loss, PV had decreased significantly more from passive than active heat stress-induced DEHydration. In addition, ΔBM accounted for 84% of the variance in PV changes during DEHydration in passive heat stress but only 42% in active heat stress, indicating that the method of dehydration appears to modulate the relationship between PV and BM changes under temperate conditions. Similar findings have been reported by [The ∆PV and ∆PAnother major finding was that, after controlling for hydration status, passive vs. exercise heat stress had a similar effect on PV and PA larger fluid shift into the vascular space, in response to active relative to passive DEHydration, could be explained by higher concentrations of vasopressin, angiotensin II, renin and aldosterone, which increase water and sodium reabsorption, and for vasopressin, may induce acute fluid shifts from extravascular compartment into intravascular space [The apparently similar effect of passive vs. exercise-heat stress on PV and PWhen rehydrating to restore BM loss, PV was incompletely restored under passive and exercise-heat stress, yet PConsistent with previous reports, heart rate increased more in dehydration than in euhydration; however, this heart rate drift was smaller than in previous studies, i.e., heart rate increased ~2 b/min per % ∆BM in this study in contrast to the 4–6 b/min per % ∆BM observed by others [