The Lab: “Sweat Rates and Electrolyte Losses of Football Players During Training Camp”
ABSTRACT
PURPOSE: Local sweat rates (LSR) and Na+, K+, and Cl- losses were investigated during the 2 week training camp in collegiate football players.
METHODS: Sweat was collected on 37 football players (20±1y; BSA=2.4±0.2m2; 7 OL, 5 WR, 4 RB, 3 TE, 1 FB, 8 DL, 3 CB, 3 LB, 3 S) using electrolyte-free cotton gauze covered by a waterproof dermal patch on the lower back. LSR was calculated by the change in gauze weight corrected for total patch surface area (g/cm2·hr). Sweat was extracted by centrifugation, electrolyte concentrations were determined by ion-selective electrodes, and total electrolyte loss was estimated by adjusting for LSR.
RESULTS: 179 sweat samples were collected during the study. Mean LSR were 0.38±0.22 g/cm2·hr (0.02–1.26 g/cm2·hr) and mean electrolyte losses were 42.1±20.5 mmol/L (8.2–107.2mmol/L, 4.6±0.9mmol/L (2.8 – 7.8 mmol/L), 39.2±18.5mmol/L (10.3–96.2 mmol/L) for Na+, K+, and Cl-, resp. Mean WBGT was 25.5±4.2°C (16.9–31.9°C). WBGT and BSA were correlated with LSR (P<0.001 both). Sweat Na+ and Cl- losses increased with an increase in LSR (P<0.001); however, K+ losses decreased (P<0.001). After adjusting for WBGT, a trend for acclimatization was observed in LSR (P=0.07).
DISCUSSION: Larger players and higher environmental heat stress produced greater sweat and Na+ losses. Sodium losses were highly variable and, in combination with large fluid losses, could result in Na+ depletion very quickly. Partial funding from the Robert and Patricia Hines Endowment in Kinesiology.
RESEARCHERS
NP. Lemoine, Jr.,1 AB. Simoneaux,1 MC. Scott,1 KS. Early,1 S. Mullenix,1 J. Marucci, 1 A. Barker,1 TS. Church,2 RR. Castle,1 NM. Johannsen,1,2; 1School of Kinesiology and Dept. of Athletics, Louisiana State University and 2Pennington Biomedical Research Center, Baton Rouge, LA
REFERENCE
Lemoine NP Jr., Simoneaux AB, Scott MC, Early KS, Mullenix S, Marucci J, Barker A, Church TS, Castle RR, Johannsen NM. Sweat Rates and Electrolyte Losses of Football Players during Training Camp. Poster at SEACSM 2016