The Lab: “Differential Sweat and Urine Electrolyte Responses in Collegiate Football Players With Sickle Cell Trait”
ABSTRACT
PURPOSE: To determine the effects of sickle cell trait (SCT) on hydration status and body temperature regulation in collegiate football players during 17 days of pre-season training.
METHODS: Twelve players were recruited to two groups: 6 with the SCT and 6 position-matched control players (CON). Body weight was measured and urine collected pre- and post-practice to examine urine color, specific gravity (USG), and electrolytes (Na+, K+, and Cl-). Sweat was collected using gauze covered by a waterproof patch on the lower back. Each player ingested a core temperature pill 4-6 hours prior to practice. Ambient and black globe temperatures and humidity were collected pre-and post-training to assess wet-blub globe temperature (WBGT).
RESULTS: Mean WBGT was 28.6±3.1°C (24.1-33.5°F). Average weight loss was -1.1±1.0kg (mean±SE). Weight loss, maximal core temp and heat storage (change in core temperature per hour) were similar in CON and SCT (P>0.05). However, SCT had significantly higher sweat sodium and chloride levels (Na+: 60.79±7.18 mmol/L; Cl-: 51.57±6.49 mmol/L) compared to CON (Na+: 47.54±7.17mmol/L; Cl-: 40.53±6.48 mmol/L; P<0.001 for both). CON had higher post-training USG (1.028±0.007) than SCT (1.018±0.007; P<0.001). Urine electrolytes were significantly higher for CON than SCT in all pre and post measurements (Pre Na+:164.06±8.74 mmol/L vs. 100.31±9.10 mmol/L; Pre-K+: 52.84±4.43 mmol/L vs. 36.50±4.59 mmol/L; Pre-Cl-: 151.36±8.50 mmol/L vs. 87.61±8.80 mmol/L and Post-Na+:118.47±8.79 mmol/L vs. 70.26±9.07 mmol/L; Post-K+: 62.74±4.61 mmol/L vs. 35.48±4.73 mmol/L, Post-Cl-: 99.06±5.14 mmol/L vs. 51.78±5.59 mmol/L, respectively; P<0.001 for all).
DISCUSSION: Sweat electrolyte levels were higher in the SCT group whereas urine electrolytes and USG were higher in CON for all measures. Future research should investigate whether the dissimilarities in sweat and urine electrolytes in SCT are meaningful and result in altered sodium or fluid balance concerns. Funded in part by the Robert and Patricia Hines Endowed Professorship in Kinesiology, LSU, and unrestricted funding provided in part by a gift to the Tiger Athletic Foundation.
RESEARCHERS
Lemoine Jr., Nathan P.1;Owens, Michael E.1; Wang, Haoyan1; Marucci, Jack1; Mullenix, Shelly1; Calvert, Derek1;Nelson, Arnold G., FACSM1, Castle, Ralph R.1; Irving, Brian A.1,2; Spielmann, Guillaume1; Rood, Jennifer2; Church, Timothy S.2; Harrell, Brian3; Johannsen, Neil M.1,2 (Sponsor: Arnold Nelson, FACSM1)
REFERENCE
Lemoine, N.P., Owens, M.E., Wang, H., Marucci, J., Mullenix, S., Calvert, D., Nelson, A., Castle, R.R., Irving, B., Spielmann, G. and Rood, J., 2018. Differential Sweat and Urine Electrolyte Reponses in Collegiate Football Players with Sickle Cell Trait: 2985 Board# 268 June 1 3. Medicine & Science in Sports & Exercise, 50(5S), p.742.