Year of Award
2020
Document Type
Thesis
Degree Type
Master of Science (MS)
Degree Name
Health and Human Performance (Exercise Science Option)
Department or School/College
Integrative Physiology and Athletic Training
Committee Chair
Brent C. Ruby
Commitee Members
John C. Quindry, Richard W. Willy
Keywords
Hydration, Thermal Stress, Carbohydrate Oxidation
Publisher
University of Montana
Subject Categories
Exercise Physiology | Exercise Science | Kinesiology | Nutrition
Abstract
Introduction: Wildfire suppression is characterized by high total energy expenditures and water turnover rates. Hydration position stands outline hourly fluid intake rates. However, dose interval remains ambiguous. We aimed to determine the effects of micro- and bolus-dosing water (MW, BW) or carbohydrate-electrolyte (MCE, BCE) solutions on fluid balance, heat stress, and carbohydrate oxidation during extended thermal exercise. Methods: Males (n=12), in a repeated measures cross-over design, completed 4, 120-minute treadmill trials (1.3 m.s-1, 5% grade, 33°C, 30%RH) wearing a USFS uniform and 15kg pack. Fluid delivery approximated losses calculated from a pre-experiment familiarization trial, providing 22 doses.h-1 or 1 dose.h-1 (46±11,1005±245 ml.dose-1). Body weight (pre-, post-exercise) and urine volume (pre-, during, post-exercise) were recorded. Heart rate, rectal temperature, skin temperature, and steady state expired air samples were recorded throughout exercise. Differences were determined via repeated measures ANOVA’s with statistical significance set at p<0.05. Results: Total body weight loss (n=11, -0.6±0.3 kg, p>0.05) and cumulative urine output (n=11, 677±440 ml, p>0.05) were not different across trials. Exercise sweat rate was lower in the MCE trial than the BCE, BW, and MW trials (n=11, 0.86±0.22, 0.93±0.21, 0.91±0.23, 0.89±0.22 ml, respectively, p<0.05). PSI was lower at minute 60 than 120 (3.6±0.7, 4.5±0.9, p<0.05), with no differences across trials. Carbohydrate oxidation was higher in the CE trials than the W trials (1.5±0.3, 0.8±0.2, g.min-1, p<0.05), with no differences between identical composition dosing styles. Conclusions: Varied fluid delivery schedules of equal volume did not affect fluid balance, PSI, and carbohydrate oxidation during extended thermal work.
Recommended Citation
Rosales, Alejandro M., "EXOGENOUS FLUID DELIVERY SCHEDULE AND COMPOSITION ON FLUID BALANCE, PHYSIOLOGIC STRAIN, AND SUBSTRATE USE IN THE HEAT" (2020). Graduate Student Theses, Dissertations, & Professional Papers. 11590.
https://scholarworks.umt.edu/etd/11590
© Copyright 2020 Alejandro M. Rosales