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EFFECTS OF 100% ORANGE JUICE CONSUMPTION ON HYDRATION MEASURES FOLLOWING EXERCISE IN THE HEAT

Abstract

Melani R. KellyƗ1,Dawn M. Emersonǂ1, Evan J. LandesƗ1, Evan R. Barnes*1, Philip M. Gallagherǂ1 1University of Kansas, Lawrence, Kansas

INTRODUCTION: In comparison to commonly consumed carbohydrate electrolyte beverages (CEB), 100% orange juice (OJ) has a similar carbohydrate content, less sodium, and an increased amount of potassium, vitamins, and minerals, making it a viable option for hydration. PURPOSE: To investigate 100% OJ, water (W), and CEB on hydration measures following exercise in the heat. METHODS: A randomized controlled, single blind design determined the effects of OJ, W, and a CEB on urine specific gravity (Usg), fluid volume (Fvol), urine volume (Uvol), heart rate (HR), blood pressure (BP), and core temperature (Tc). Participants (n = 26, 20 male, 6 female, age: 22.1 ± 3.3 years; weight: 72.9 ± 10.0 kg; height: 174.3 ± 7.9 cm; VO2max: 48.8 ± 7.3 mL/kg/min) consumed 237 mL of assigned beverage on 5 consecutive days following 80 minutes of cycling at 70% of their VO2max in a hot, humid environment (30.1 ± 0.2°C, 51.6 ± 4.0% relative humidity). Dependent measures were taken pre-, during, post-, and 1 hour post-cycling (1hr). RESULTS: There were no significant differences between conditions at any time point (pre-, during, or post-cycling) for Usg, Fvol, Uvol, HR, BP, or Tc. Further, there were no significant differences in dependent measures pre-cycling between conditions for Days 4-8. All participants began exercise euhydrated (Usg = 1.011 ± 0.00) and did not significantly change to post-cycling but significantly increased from post- to 1hr post-cycling (1.009 ± 0.01 to 1.013 ± 0.00, P < .001). Overall, participants excreted significantly less urine during 1hr rest compared to during exercise (778.0 ± 283.3 mL to 476.3 ± 228.3 mL, P < .001). Overall, HR significantly increased pre- to post-cycling (76.0 ± 12.2 bpm to 141.3 ± 9.7 bpm, P < .001), and significantly decreased from post-cycling to 1hr (76.1 ± 7.8 bpm, P < .001). Likewise, systolic BP significantly increased pre- to post-cycling (120.9 ± 8.4 mmHg to 131.7 ± 8.8 mmHg, P < .001) and significantly decreased from post-cycling to 1hr (118.3 ± 8.1 mmHg, P < .001). Tc significantly increased pre- to post-cycling (36.7 ± 0.3°C to 37.6 ± 0.3°C, P < .001) and decreased during 1hr (36.9 ± 0.2°C P < .001). CONCLUSION: Consuming 8 ounces of 100% OJ on multiple days after intense exercise in the heat maintained hydration, cardiovascular, and core temperature levels similar to using W or CEB.

This study was funded by a grant from the Florida Department of Citrus (#STE0075600).

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