Date of Award

Spring 2018

Document Type

Thesis Restricted

Degree Name

Master of Science (MS)



Committee Chairperson

Sandra Fowkes Godek, Ph.D., ATC

Committee Member

Katherine Morrison, Ph.D., ATC

Committee Member

Christine Karpinski, Ph.D., RD


Context: Racial differences in the renin-angiotensin-aldosterone system (RAAS) have been implicated in the disparity in the prevalence of hypertension in Americans. The RAAS is a primary mechanism for sodium conservation during exercise. Purpose: To investigate racial differences in the RAAS and its relationship to sweat and urine electrolyte losses during exercise. Methods: Data was collected before the first pre-season practice and during football and soccer practice on day 10 of practices. Eight Caucasian and 8 African-American male division II collegiate football and soccer players volunteered and did not differ in physical characteristics. Venous blood samples (8 mL) were drawn before the first pre-season practice (baseline) and on day 10 of practices. Sweat and urine electrolyte concentrations (mmol/L) were analyzed by ion-selective electrodes. Results: Significant differences were found in renin at baseline (Caucasian: 1.22 ± 0.56 ng/dL/hr, African-American: 0.57 ± 0.22 ng/dL/hr, p = 0.013) and at pre-practice (Caucasian: 1.30 ± 0.51 ng/dL/hr, African-American: 0.77 ± 0.34 ng/dL/hr, p = 0.042). Post-practice concentrations of urine sodium (Caucasian: 48.8 ± 33.7 mmol/L, African-American: 97.7 ± 40.1 mmol/L, p = 0.029) and chloride (Caucasian: 95.2 ± 49.7 mmol/L, African-American: 151.5 ± 42.7 mmol/L, p = 0.039) also differed. Correlations between between electrolyte losses and measurement of the RAAS were found to be significant in both races, but never simultaneously. Conclusions: These results suggest a potential racial difference in the influence of these hormones on the mechanism by which electrolytes are lost and need to be replaced in African-American versus Caucasian athletes.