Resistance Training & Milk Study

Resistance Training & Milk Study - Consumption of fat-free...

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Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters 1–3 Joseph W Hartman, Jason E Tang, Sarah B Wilkinson, Mark A Tarnopolsky, Randa L Lawrence, Amy V Fullerton, and Stuart M Phillips ABSTRACT Background: Acute consumption of fat-free fluid milk after resis- tance exercise promotes a greater positive protein balance than does soy protein. Objective: We aimed to determine the long-term consequences of milk or soy protein or equivalent energy consumption on training- induced lean mass accretion. Design: We recruited 56 healthy young men who trained 5 d/wk for 12 wk on a rotating split-body resistance exercise program in a parallel 3-group longitudinal design. Subjects were randomly as- signed to consume drinks immediately and again 1 h after exercise: fat-free milk (Milk; n ± 18); fat-free soy protein (Soy; n ± 19) that was isoenergetic, isonitrogenous, and macronutrient ratio matched to Milk; or maltodextrin that was isoenergetic with Milk and Soy (control group; n ± 19). Results: Muscle fiber size, maximal strength, and body composition by dual-energy X-ray absorptiometry (DXA) were measured before and after training. No between-group differences were seen in strength. Type II muscle fiber area increased in all groups with training, but with greater increases in the Milk group than in both the Soy and control groups ( P ² 0.05). Type I muscle fiber area in- creased after training only in the Milk and Soy groups, with the increaseintheMilkgroupbeinggreaterthanthatinthecontrolgroup ( P ² 0.05). DXA-measured fat- and bone-free mass increased in all groups, with a greater increase in the Milk group than in both the Soy and control groups ( P ² 0.05). Conclusion: We conclude that chronic postexercise consumption of milk promotes greater hypertrophy during the early stages of resis- tance training in novice weightlifters when compared with isoener- getic soy or carbohydrate consumption. Am J Clin Nutr 2007; 86:373–81. KEY WORDS Hypertrophy, strength, resistance exercise, protein INTRODUCTION The accretion of muscle protein as a result of resistance exer- cise occurs because of successive periods of positive muscle protein balance (1–3). Periods of positive protein balance are due to a synergistic interaction of an exercise and feeding-induced stimulation of muscle protein synthesis (MPS) (4–7). Protein ingestion provides essential amino acids for protein synthesis (8, 9), which also act, in the case of leucine, to stimulate the trans- lational machinery [for review see Kimball and Jefferson (10)]. Protein ingestion also increases systemic insulin, which has a mild stimulatory effect on MPS (11, 12). Rather than a dose- dependent stimulation, a minimal threshold of insulin is required to allow MPS to proceed unabated; however, further stimulation of MPS is not seen at higher doses [for reviews see Kimball et al (13, 14)].
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This note was uploaded on 09/08/2010 for the course NUFS 31 at San Jose State University .

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Resistance Training & Milk Study - Consumption of fat-free...

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