Efficacy of a Resistance Training Program on Muscle Mass and Muscle Strength in Adults Following a Vegan Versus Omnivorous Diet: A Non-Randomized Four-Arm Parallel Clinical Trial”

Abstract

Introduction A vegan diet may lead to certain nutritional deficiencies that could potentially affect muscle mass and strength. Nevertheless, strength training serves as a natural anabolic stimulus that promotes increases in skeletal muscle mass and reductions in fat mass. Objective: To evaluate the effectiveness of a 16-week resistance training program in adults following a vegan diet compared with those following an omnivorous diet, focusing on changes in musculoskeletal mass and muscular capacity. Materials and Methods A non-randomized controlled clinical trial with four parallel groups compared baseline and post-intervention measurements in individuals aged 18–60 years from the Biobío and La Araucanía regions of Chile who had maintained either diet for at least six months. Results The vegan diet intervention group increased right-hand grip strength by 4 kg (p<0.001) and left-hand grip strength by 2 kg (p<0.001). They gained 0.50 kg in one-repetition-maximum (1RM) strength (p<0.001) and improved vertical jump height by 3 cm (p<0.01). The omnivorous diet intervention group increased right-hand grip strength by 2 kg (p<0.001) and left-hand grip strength by 5 kg (p<0.001), gained 0.45 kg in 1RM (p<0.001), and improved vertical jump height by 0.75 cm (p<0.04). Conclusion No significant changes in musculoskeletal mass were observed in any of the groups. Resistance training significantly improved muscle strength regardless of diet type, suggesting that a vegan diet did not compromise adaptations to strength training.