Lee, D., Oh, J., Park, H., & Kim, Y. (2006). Effects of resistance training and protein supplementation on muscle strength, body composition, liver and kidney. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1994.

This study investigated the effects of eight weeks of resistance training and protein supplementation on muscle strength, body composition, and liver and kidney function. Males (N = 45) were divided into six groups(three exercise groups; E1(N = 5) no protein supplementation, E2 (N = 5) protein concentration of 1 g/kgBW, and E3 (N = 7) protein concentration of 3 g/kgBW, and three non-exercise control groups; C1 (N = 11) no protein supplementation, C2 (N = 9) protein concentration of 1 g/kgBW, and C3 (N = 8) protein concentration of 3 g/kgBW. Supplementation groups consumed protein supplements three days per week. Exercise groups participated in a resistance training program three non-consecutive days per week. Each training session was about one hour and included 8-10 exercises. Dietary intake was analyzed by 24-hour recall using diet analysis software to examine the baseline. Muscle strength was determined by squat and bench press 1 RM. Bioelectrical impedance analysis was used to measure body composition (muscle mass, % body fat). Liver and kidney functions were assessed by serum GOT, GPT, and creatinine level.

There were significant effects of exercise on muscle strength, muscle mass, and % body fat, but no effects on GOT, GPT, and creatinine. There was no interaction between protein supplementation and protein-exercise. Between pre- and post-analysis, squat 1 RM increased in E1 and E3; bench press 1 RM increased in all three exercise groups; muscle mass and % body fat were improved in all exercise groups; creatinine decreased in E3; and there were no changes in GOT and GPT. All exercise groups showed positive changes in muscle strength and body composition. There were no changes in any variables in the non-exercise groups except squat 1 RM increased in C1. No dietary intake differences were found among the six groups.

Implication. Regardless of protein supplementation, eight weeks of resistance training improved muscle strength and body composition in young men. Protein supplementation of up to 3 g/kgBW did not show any changes in liver or kidney function.

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