Date of Award

Spring 2023

Document Type

Open Access Thesis


Exercise Science

First Advisor

Shawn Arent


Intro: Dehydration is common in athletes and can lead to reductions in cognitive and physical performance. While there are many commercially available hydration beverages, most contain high amounts of CHO and are marketed as functional beverages. The purpose of this study was to determine the effects of two novel hydration beverage formulas (HMAA, HM) on hydration, cognitive performance, and time to exhaustion (TTE). Methods: Sixteen subjects (n=8 women, n=8 men) completed three experimental days where they consumed one of three conditions (HMAA, HM, or placebo) assigned randomly. The experimental protocol was completed in a heat chamber at 30-32℃ and 45-50% relative humidity (RH) with a fixed-rate drinking strategy. Each visit consisted of a 75-min dehydration trial at a power output that elicited 65% VO2max, 120-min seated rest, and time to exhaustion (TTE) at 70% of the power output at VO2max. Following TTE, participants completed the NIH cognitive toolbox – Flanker Inhibitory Control and Attention (FICA) testing. Data were then analyzed using mixed effect models (MEM), area under the curve (AUC), one-way ANOVAs, and when warranted, post hoc testing. Results: No condition effects were detected for changes in PV or changes in body mass but there were significant time effects. During the 75-min dehydration trial, average percentages of max HR were significantly lower with HMAA compared to HM (p = 0.019) with a moderate effect size (d = 0.50). We detected a small effect size (d = 0.31) during TTE, but differences were not significant (HMAA: 16.2 ± 11.0 min; HM 15.0 ± 9.1 min; Placebo 13.2 ± 8.1 min). Reaction time (RT) was improved with HMAA (p = 0.003; d = -0.44) and HM (p = 0.044; d = -0.51) compared to placebo. Using incongruent stimuli, HMAA performed significantly better (p = 0.02, d = -0.37). We did not find any significant condition effects for participant reported subjective outcomes. Lastly, there were no differences in plasma electrolyte levels between conditions. Conclusions: Our findings do not support the use of HMAA or HM to enhance hydration beyond water. However, we detected greater TTE, less physiological strain, and improved cognitive performance with HMAA and HM indicating there were performance benefits compared to flavored water.


© 2023, Nathaniel David Rhoades