| Abstrakt: |
Runners are unlikely to consume fluid during training bouts increasing the importance of recovery rehydration efforts. This study assessed urine specific gravity (U SG ) responses following runs in the heat with different recovery fluid intake volumes. Thirteen male runners completed 3 evening running sessions resulting in approximately 2,200 ± 300 ml of sweat loss (3.1 ± 0.4% body mass) followed by a standardized dinner and breakfast. Beverage fluid intake (pre/postbreakfast) equaled 1,565/2,093 ml (low; L), 2,065/2,593 ml (moderate; M) and 2,565/3,356 mL (high; H). Voids were collected in separate containers. Increased urine output resulted in no differences (p > .05) in absolute mean fluid retention for waking or first postbreakfast voids. Night void averages excluding the first void postrun (1.025 ± 0.008; 1.013 ± 0.008; 1.006 ± 0.003), first morning (1.024 ± 0.004; 1.015 ± 0.005; 1.014 ± 0.005), and postbreakfast (1.022 ± 0.007; 1.014 ± 0.007; 1.008 ± 0.003) U SG were higher (p < .05) for L versus M and H respectively and more clearly differentiated fluid intake volume between L and M than color or thirst sensation. Waking (r = -0.66) and postbreakfast (r = -0.71) U SG were both significantly correlated (p < .001) with fluid replacement percentage, but not absolute fluid retention. Fluid intake M was reported as most similar to normal consumption (5.6 ± 1.0 on 0-10 scale) after breakfast and equaled 122 ± 16% of sweat losses. Retention data suggests consumption above this level is not warranted or actually practiced by most runners drinking ad libitum, but that periodic prerun U SG assessment may be useful for coaches to detect runners that habitually consume low levels of fluids between training bouts in warm seasons. |
