Evaluation of Exercise With Overdressing to Induce Heat Acclimation in an Average Fitness Warfighter

A randomized, crossover trial examining five days of exercise \& standardized overdressing versus exercise alone.

Inclusion Criteria: * Male or female, age 18-45 (17 if active-duty military). * In good health as determined by the Office of Medical Support \& Oversight (OMSO) General Medical Clearance. * Performs aerobic exercise at least 2 times per week and 2 mile run time is between 14:30 and 20:00 minutes. * Willing to abstain from exercise and alcoholic beverages for 24 hours before each study visit. * Willing to abstain from caffeine for 12 hours prior to all study visits. * Willing to abstain from food for 2 hours prior to all study visits. * Have supervisor approval if permanent party military or a federal employee at U.S. Army Natick Soldier System Center. Exclusion Criteria: * Frequent hot bath or sauna users (e.g., more than three times a week for the past month). * Females who are pregnant or planning to become pregnant during the study. * Females who are menopausal or postmenopausal * Taking dietary supplements, prescriptions, or over the counter medication, other than a contraceptive (unless approved by OMSO \& PI). * Any nicotine or recreational drug use (unless quit 1 month prior to the start of the study) * Abnormal blood count during OMSO medical screening (For example: hemoglobin (Hb) outside of the typical normal values reported by LabCorp in accordance with OMSO (Normal \[Hb\] Males = 12.6-17.7 g/dL; Females = 11.1-15.9 g/dL) or hematocrit (Hct) outside of the normal ranges (Normal Hct Males = 37.5-51.0%; Females = 34.0-46.6%) levels, presence of abnormal blood chemicals (hemoglobin S or sickle cell traits). * Any history of pulmonary, cardiovascular, or renal disease (unless approved by OMSO \& PI). * Uncontrolled asthma. * Current or recent respiratory tract or sinus infections (\< 2 weeks prior). * Blood donation (i.e., 550 mL whole blood) during the study or 8 weeks before and after the study * History of heat stroke or orthostatic intolerance. * Diagnosed and/or treated for fluid/electrolyte imbalance within the last 30 days. * History of obstructive disease of the gastrointestinal tract including (but not limited to) diverticulosis, diverticulitis and inflammatory bowel disease, peptic ulcer disease, Crohn's disease, ulcerative colitis. * Scheduled MRI during testing. * Allergies to adhesives (e.g., medical tape).