Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2006
Publication Date: 5/1/2007
Citation: Horswill, C.A., Stover, E.A., Lukaski, H.C., Mjaanes, J.M., Murray, R. 2007. Electrolyte concentrations in the sweat of young soccer players. Medicine and Science Sport and Exercise. 39:S278.
Technical Abstract: PURPOSE: We examined sweat electrolyte content during training in elite young soccer players to determine whether gender or age differences existed. METHODS: Male and female subjects who were members of an elite soccer club in California representing the ages groups of 9-to-10-y (U10 y, n=5), 11-to-12-y (U13-y, n=10) and 14-to-15-y (U16 y, n=11) volunteered to participate. Samples were collected during a practice conducted by the club’s coach in the subjects’ typical training environment. All subjects provided a pre-practice urine sample to assess their hydration status via urine specific gravity (USG). Body weight measurements were taken before and after practice in either dry shorts (males) or swim suits (females). For fluid intake during training, subjects were provided drink bottles that were weighed before and after practice; the intake was used to calculate sweat rate. Sweat patches were placed on the forehead, scapula, chest, forearm, and thigh immediately after the skin sites were washed with de-ionized water. Data presented here are for back site only (consistent with site presented by Meyer et al MSSE 1995). Prior to data collection, all collection and storage materials were washed with Radiac, rinsed with de-ionized water, and dried to remove contaminating minerals. Sweat samples were analyzed for sodium (Na), potassium (K), and magnesium (Mg+2) concentrations using inductive coupled plasma mass spec. Data were analyzed using ANOVA for age effects and independent t-test for gender differences. RESULTS: Median ± SD in mEq/L U10 y U13 y U16 y Na+ 43.4 ± 14.7 63.1 ± 21.9 79.6 ± 47.7 K+ 6.1 ± 1.5 5.9 ± 0.5 6.0 ± 1.7 Mg+2 0.21 ± 0.08 0.20 ± 0.08 0.22 ± 0.48 The respective median values (mEq/L ±SD) for males and females were as follows: Na+, 77 ± 41.6 and 51.6 ± 14.5; for K+, 6.1 ± 1.2 and 5.9 ± 1.3; and for Mg+2, 0.20 ±0.07 and 0.22 ±0.08. A trend existed for an age group effect for Na+ (p=0.12) and males had a higher concentration of sweat Na+ than did females (p<0.05). CONCLUSION: Generally the sodium and potassium concentrations fell within the ranges previously reported for adults, although the sodium values were compared to those previously published on youth. Magnesium levels in the sweat of these young subjects were below the low end of the range reported in adults.