Beverage Content Influences Voluntary Fluid Intake During Exercise: A Systematic Review: 2034 Board #186 June 2, 2: 00 PM - 3: 30 PM.

Abstract

Oxidative stress is known to be involved in many adverse mechanisms. Few studies have examined the effects of dehydration on oxidative stress. PURPOSE: Examine the effect of dehydration on plasma oxidative stress and antioxidant capacity in collegiate athletes. METHODS: Eighty-two athletes (56 male, 26 female) were recruited to undergo an acute dehydration (3% body weight), rehydration protocol. Subjects reported to the lab for baseline anthropometrics and blood sampling. The dehydration protocol required subjects to participate in their respective training until 3% of pre-weight body mass was lost. They reported back to the lab where a blood sample was immediately collected. Subjects then drank Gatorade until body weight was reestablished to baseline values. Plasma was collected at 80 min post full re-hydration (PFR) and snap frozen in liquid nitrogen and stored at -80 degrees Celsius until analysis. Oxidative stress was determined by measuring F2-isoprostane lipid oxidation via EIA kit. Ferric reducing ability of plasma (FRAP) was used to measure plasma antioxidant potential. Plasma osmolality was determined by freezing point depression by an osmometer. Statistical analysis consisted of 1-way ANOVA. All values are reported as mean ± SD. RESULTS: Plasma osmolality (280.9 mOsm ± 14.2) significantly elevated (286.2 mOsm ± 15.8) post exercise (p= 0.031), but returned to below normal values (282.1 mOsm ± 15.3) PFR. Plasma FRAP (uM/L ascorbate equivalents) values also increased post dehydration (pre: 0.237 ± 0.068, post: 0.286 ± 0.279), and decreased to near baseline levels PFR (0.247 ± 0.150) but only exhibited a statistical trend (P=0.08). Mean concentrations of F2-isoprostanes (pg/mL) declined from (437.6 ± 125.5) at baseline to (77.5 ± 496) post dehydration, and then rose to (699.73 ± 154.2) PFR (p<0.001). CONCLUSIONS: This study indicates that dehydration causes dramatic increases in plasma osmolality and antioxidant potential. Increased concentrations of antioxidants might be responsible for the reduction in F2-isoprostanes immediately post exercise. This decrease is followed by a large increase at 80 min post full rehydration despite normalization of plasma osmolality. The reasons for the decrease post dehydration and increase after rehydration in F2-isoprostanes warrants further examination.