Essential Amino Acids and High Intensity Interval Training

Purpose: The primary purpose is to determine the combined effects of essential amino acids (EAA) supplementation and high intensity interval training (HIIT) on body composition, muscle characteristics, and muscle architecture in overweight men and women over the course of eight weeks. A secondary purpose is to determine the metabolic effects of EAA supplementation and HIIT on whole body protein turnover, metabolic rate, substrate metabolism, and metabolomics. A tertiary purpose is to evaluate the modulatory effects of sex on body composition, metabolism, metabolic profile, cardiorespiratory fitness, and hunger and satiety in response to EAA supplementation and HIIT. Participants: Healthy overweight and obese men and women (30-50 years) Procedures (methods): In a block randomized design, 78 healthy, overweight or obese men and women will be randomized, to one of four, eight-week intervention groups using a 2:2:2:1 group allocation design: 1) essential amino acids (EAA) supplementation (7.2 grams EAA daily); 2) HIIT, two days per week of cycle ergometry training; 3) EAA + HIIT; or 4) control (CON), receiving no intervention. Measurements of body composition, muscle characteristics, resting metabolic rate, substrate metabolism, and cardiorespiratory fitness will be measured at baseline, 4-weeks, and 8-weeks. Metabolomics and whole body protein turnover will also be measured at baseline and 8-weeks. Subjects will be asked to arrive to testing sessions following a 12 hour fast (except for water), consuming no food, caffeine, or alcohol. Participants will also be asked to abstain from physical activity for 24 hours prior to testing. Subjects will complete one electronic contact (phone/email screening) and up to 22 in-person sessions (enrollment; 5 testing sessions \[2 at base, 1 at 4week, 2 at 8week\]; 16 training sessions \[for HIIT and EAA+HIIT\]) over the course of 8 weeks.