Post-exercise Recovery After Dietary Protein Ingestion in Healthy Young Men (Meat-Milk Study)

Rationale: The consumption of dietary protein immediately after exercise is necessary to maximally stimulate muscle protein synthesis rates (24, 37). Recent work suggests that the type of protein consumed (e.g., animal vs. plant-derived proteins) during post-exercise recovery can affect the amplitude of acute increases in muscle protein synthesis rates (25, 31). Specifically, consumption of bovine milk proteins immediately after a single bout of resistance exercise stimulates muscle protein synthesis rates greater than consumption of an isonitrogenous soy-protein beverage (31, 37). Importantly, consumption of milk promotes greater hypertrophy than soy after resistance training (10). Thus, it is generally assumed that the acute muscle protein synthetic response predicts long-term training outcomes, such as hypertrophy. Currently, a great amount of work has been carried out to study the effects of consuming milk proteins on muscle protein synthesis rates after resistance exercise (5, 7, 26, 32). However, very little is known about the effects of other types of high-quality animal proteins, such as beef, on stimulating post-exercise muscle protein synthesis rates. Further describing the muscle protein synthetic response after consumption of other types of high-quality animal proteins will provide valuable information for individuals with milk allergies, lactose intolerance, or simply a strong dislike of dairy products.

Objective: To investigate whether the in vivo post-resistance exercise muscle protein synthetic response is augmented when minced beef is ingested as compared to an isonitrogenous-matched milk protein beverage in healthy young men.

Study design: Crossover, randomized

Study population: 12 healthy young males (18-35 y).

Intervention: Subjects will perform resistance exercise and consume either a piece of meat (135 grams, 35 g of protein) or an isonitrogenous-matched milk protein beverage on two separate test days. In addition, continuous intravenous tracer infusions will be applied, with plasma and muscle samples collected. A two week 'wash-out' period will be included between trials.

Main study parameters/endpoints Primary endpoint: Muscle protein synthetic rate, expressed as fractional synthetic rate (FSR). Secondary endpoints: Rate of protein digestion and absorption and whole body protein balance.