Consistently high urine specific gravity in adolescent American football players and the impact of an acute drinking strategy.
The purpose of this study was to determine whether high-school football players showed risks of fluid deficits during two-a-day training (Part 1), and whether implementing a drinking strategy could acutely improve the markers of hydration (Part 2). In Part 1, pre-training urine specific gravity (USG) and pre- and post-training body weight were measured at the morning session for 5 consecutive days of two-a-day practices to monitor the hydration status of 13 varsity players. The mean pre-training body weight was consistently lower (mean decrease of 0.5 kg, p<0.05) following the first day of measurement. Pre-training USG values remained consistently high each day (range for daily means: 1.022+/-0.003 to 1.024+/-0.005). Part 2 consisted of assessing hydration status in 46 varsity and junior varsity players prior to morning training during two-a-day training before and following implementing a drinking strategy. In association with the strategy, mean body weight increased 0.5 kg (p<0.01) and mean USG decreased from 1.021 to 1.016 (p<0.01) following the drinking protocol. The slight decline in body weight and consistently high USG (Part 1) suggested that standard fluid replacement strategies were less than optimal for a majority of the players. Implementing a drinking strategy appeared to improve hydration status based on changes in body weight and USG (Part 2).
Stover
E A
EA
Gatorade Sports Science Institute, Barrington, IL 60010, USA.
Zachwieja
J
J
Stofan
J
J
Murray
R
R
Horswill
C A
CA
D000293:Adolescent; D001835:Body Weight / Q000502:physiology; D003681:Dehydration / Q000503:physiopathology / Q000517:prevention & control; D004327:Drinking Behavior / Q000502:physiology*; D005538:Football / Q000502:physiology*; D018882:Heat Stress Disorders / Q000503:physiopathology / Q000517:prevention & control; D006801:Humans; D008297:Male; D013046:Specific Gravity; D013546:Sweating / Q000502:physiology; D014556:Urine / Q000737:chemistry*; D014882:Water-Electrolyte Balance / Q000502:physiology