Effects of 16 weeks of two different high-protein diets with either resistance or concurrent training on body composition, muscular strength and performance, and markers of liver and kidney function in resistance-trained males

Abstract

Purpose It is unclear whether resistance (RT) and concurrent training (CT; resistance plus endurance training) combined with different protein intakes have differential effects on muscle hypertrophy, strength, and performance. Therefore, we compared the effects of two high-protein diets (1.6 or 3.2 g.kg−1.d−1) during 16 weeks of either CT or RT alone in resistance-trained males. Methods Forty-eight resistance-trained males (age: 26 ± 6 yr, body mass index: 25.6 ± 2.9 kg.m−2) performed 16 weeks (four sessions·w−1) of CT or RT with either 1.6 g.kg−1.d−1 protein (CT1; n = 12; RT1; n = 12) or 3.2 g.kg−1.d−1 protein (CT2; n = 12; RT2; n = 12). Training adaptations were assessed pre-, mid-, and post-intervention. Results All measures of performance (endurance, vertical jump, and pull-up), lean mass, muscle strength, and power significantly increased post-intervention in all groups, but peak power gains were greater in RT2 compared with RT1 and CT1 (p .05). Conclusions With the exception of peak power, intake of 1.6 g.kg−1.d−1 of protein appears sufficient to maximize gains in lean mass, muscle strength, performance, and aerobic capacity during both RT and CT without influencing markers of kidney and liver function, indicating this daily protein amount is effective and safely tolerated in young, healthy adults.

Keywords

• concurrent exercise
• protein intake
• skeletal muscle adaptation
• exercise performance