RESUMO
This study documented 20 h rehydration from intermittent running while concealing the primary outcome of rehydration from subjects. Twenty-eight male team sports athletes (age 25 ± 3 y; predicted VÌO2max 54 ± 3 mL kg-1 min-1) were pair-matched to exercise (EX) or rest (REST) groups. To determine hydration status, body mass, urine and blood samples were collected at 08:00, pre-intervention (09:30), post-intervention (12:00), 3 h post-intervention and 08:00 the following morning (20 h). The intervention was 110 min intermittent running (EX) or seated rest (REST), with ad-libitum fluid provided in both. Subjects completed a weighed diet record and collected all urine for the 24 h. Changes typical of hypohydration were apparent in EX following the intervention period (body mass: EX -2.0 ± 0.5%; REST -0.2 ± 0.3%; serum osmolality: EX 293 ± 4 mOsmâkgH2O-1; REST 287 ± 6 mOsmâkgH2O-1; P ≤ 0.022). Fluid intake during the intervention period (EX 704 ± 286 mL, REST 343 ± 230 mL) and fluid intake within the first 3 h post-intervention (EX 1081 ± 460 mL, REST 662 ± 230 mL) were greater (P ≤ 0.004), and 24 h urine volume lower (EX 1697 ± 824 mL, REST 2370 ± 842 mL; P = 0.039) in EX. Compared to baseline, body mass remained lower (-0.6 ± 0.5%; P = 0.030) and urine osmolality elevated (20 h: 844 ± 197 mOsmâkgH2O-1, 08:00: 698 ± 200 mOsmâkgH2O-1; P = 0.004) at 20 h in EX. When games players drank fluid ad-libitum during exercise and post-exercise in free-living conditions, a small degree of hypohydration remained 20 h post-exercise.