Sweat rates, sweat sodium concentrations, and sodium losses in 3 groups of professional football players

Abstract

Context: Sweat sodium losses have never been reported in a large cohort of American football players. Objective: To compare sweat rates (SwtRs), sweat sodium concentrations (SwtNa+), and sodium losses in 3 groups of players (backs and receivers [BK], linebackers and quarterbacks [LB/QB], and linemen [LM]) to determine if positional differences and, therefore, size differences exist. Design: Observational study. Setting: Data were collected during practices in the second week of 2 consecutive training camps. The wet bulb globe temperature was 78.5°F ± 3.5°F (25.96C ± 1.9°C). Patients or Other Participants: Eighteen BK, 12 LB/QB, and 14 LM volunteered. Intervention(s): Sterile sweat patches were applied to the right forearm after the skin was appropriately cleaned. The patches were removed during practice, placed in sterile tubes, centrifuged, frozen, and later analyzed by flame photometry. Main Outcome Measure(s): Sweat rate, SwtNa+, and sodium loss. We calculated SwtR by change in mass adjusted for urine produced and fluids consumed divided by practice time in hours. Results: Other than age, physical characteristics were different among groups (P