The effect of hypohydration before and different rehydration strategies after severe intensity exercise on...

We examined the effect of 12 h of fluid deprivation before, and three different rehydration strategies (none, fixed volume, and ad libitum drinking) after exercise on post-exercise hypotension (PEH) in 12 normotensive Asian men. The participants underwent four experimental trials, comprising euhydration (Eu), dehydration only (De), dehydration with fixed fluid intake (De + Fixed) and dehydration with ad libitum fluid intake (De + Ad). The participants completed one of the dehydration trials at the severe intensity domain until volitional exhaustion. All other trials were strictly matched for the time to exhaustion reported in the dehydration trial (698 ± 179 s), with a 1-h recovery in all trials. The dehydration trials (De, De + Fixed and De + Ad) induced higher resting plasma osmolality (291 ± 4, 294 ± 6, 294 ± 4 vs. 287 ± 4 mOsm/kg, respectively), urine specific gravity and haematocrit (all P < 0.03) than Eu. The peak reduction in post-exercise diastolic blood pressure was larger in De (- 12 ± 2 mm Hg) than in Eu (- 6 ± 1 mm Hg), De + Fixed (- 4 ± 2 mm Hg) and De + Ad (- 5 ± 2 mm Hg), as was the reduction in mean arterial pressure (De: - 11 ± 2 vs - 7 ± 1, - 5 ± 1 and - 5 ± 1 mm Hg, all P < 0.05). These reductions did not differ across Eu, De + Fixed and De + Ad (all P > 0.80). No effects of dehydration on systolic pressure were observed (P = 0.06). Dehydration exacerbated PEH whilst fixed and ad libitum drinking during the post-exercise period were equally effective at mitigating hypotension in Asian men.