Date of Graduation

Spring 2026

Degree

Master of Science in Kinesiology

Department

School of Heath Sciences

Committee Chair

Ryan Gordon

Abstract

Glucagon-like-peptide 1 receptor agonists (GLP-1 RAs) exert significant weight loss through appetite suppression and caloric restriction. Semaglutide, a common GLP-1 RA, leads to weight loss comprised from both fat mass (FM) and fat free mass (FFM). Semaglutide is a promising medication to treat and prevent obesity, but long-term outcomes relating to body composition, muscular function, and metabolic health remain unknown. This study observed changes in body composition, muscular function, and metabolic health in 11 middle-aged (30-55 years) adults using semaglutide for weight loss after a four-week period of no resistance training (RT) and after an eight-week RT protocol. Assessments included body composition (using air displacement plethysmography (ADP) to categorize fat mass [FM] and fat-free mass [FFM]), muscular size and quality (using B-mode ultrasonography to measure muscle thickness [MT], cross-sectional area [CSA], and corrected echo intensity [cEI]), strength performance (handgrip, 10-repetition maximum of leg press and chest press), blood glucose regulation (fasting blood glucose [FBG] and glycated hemoglobin [HbA1c]), and resting metabolic rate (RMR). Over 12 weeks, we observed retention of FFM despite significant decreases in FM (-14.8%, p = .007) and body fat percentage (BF%; -4.2%, p = .013). Additionally, MT, CSA, and cEI assessed via B-mode ultrasonography improved, albeit insignificantly. Participants saw significant improvements in 10RM of leg press (+55.3%, p < .001) and chest press (+18.1%, p = .005) , while handgrip strength did not change. General improvements in metabolic health (e.g., decrease in HbA1c [-0.2%, p = .076] and maintenance of RMR [+5.7%, p = .205) were observed. These results support that reduced metabolic rate, lean mass loss, and strength loss are not inevitabilities while using semaglutide, if medication use is combined with RT. In the era of incretin-therapies, this study provides evidence supporting RT as a promising intervention to be used in conjunction with GLP-1 RA use to promote functional and metabolic health across the lifespan, leading to better outcomes during use and potentially after discontinuation.

Keywords

GLP-1 RA, semaglutide, body composition, middle-aged, muscle mass, strength, blood glucose, metabolism, ultrasound, resistance training

Subject Categories

Exercise Physiology | Exercise Science | Sports Sciences

Copyright

© Charles Hill

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Available for download on Monday, May 01, 2028

Open Access

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