Sweat rate and fluid turnover in American football players compared with runners in a hot and humid environment.
OBJECTIVE
To determine sweat rate (SwR) and fluid requirements for American footballers practicing in a hot, humid environment compared with cross country runners in the same conditions.


METHODS
Fifteen subjects, 10 footballers and five runners, participated. On the 4th and 8th day of preseason two a day practices, SwR during exercise was determined in both morning and afternoon practices/runs from the change in body mass adjusted for fluids consumed and urine produced. Unpaired t tests were used to determine differences between groups.


RESULTS
Overall SwR measured in litres/h was higher in the footballers than the cross country runners (2.14 (0.53) v 1.77 (0.4); p<0.01). Total sweat loss in both morning (4.83 (1.2) v 1.56 (0.39) litres) and afternoon (4.8 (1.2) v 1.97 (0.28) litres) practices/runs, and daily sweat losses (9.4 (2.2) v 3.53 (0.54) litres) were higher in the footballers (p<0.0001). The footballers consumed larger volumes of fluid during both morning and afternoon practices/runs (23.9 (8.9) v 5.5 (3.1) ml/min and 23.5 (7.3) v 13.6 (5.6) ml/min; p<0.01). For complete hydration, the necessary daily fluid consumption calculated as 130% of daily sweat loss in the footballers was 12.2 (2.9) litres compared with 4.6 (0.7) litres in the runners (p<0.0001). Calculated 24 hour fluid requirements in the footballers ranged from 8.8 to 19 litres.


CONCLUSIONS
The American footballers had a high SwR with large total daily sweat losses. Consuming large volumes of hypotonic fluid may promote sodium dilution. Recommendations for fluid and electrolyte replacement must be carefully considered and monitored in footballers to promote safe hydration and avoid hyponatraemia.
Godek
S Fowkes
SF
Department of Sports Medicine, West Chester University, 214 Sturtzabecker Health Science Center, West Chester, PA 19383, USA. sfowkesgod@wcupa.edu
Bartolozzi
A R
AR
Godek
J J
JJ
D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology; D001835:Body Weight; D004326:Drinking; D005538:Football / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007010:Hyponatremia / Q000517:prevention & control; D010806:Physical Education and Training; D012420:Running / Q000502:physiology*; D013546:Sweating / Q000502:physiology*; D014556:Urine / Q000737:chemistry; D014882:Water-Electrolyte Balance / Q000502:physiology