Pump It Up With (Milk) Protein

Anyone who pumps iron likely knows consuming protein after a workout helps build muscle mass. Researchers from McMaster University, Hamilton, Canada, set out to determine which kind of proteinmilk-based or soy-basedwas most effective in building muscle.

For the crossover study, eight healthy men who regularly lift weights were given either a soy beverage or skim milk after performing a series of leg exercises. Then, arterial-venous amino acid balance and muscle fractional synthesis rates were measured for three hours after the workout. Muscle uptake of amino acids was significantly greater after drinking the skim milk.

Soy is more quickly digested and temporarily floods the blood with amino acids, the researchers note. But the slower-to-digest casein found in milk produced a more gradual, long-lasting increase in amino acids in the blood.

According to the study, published in the American Journal of Clinical Nutrition (2007; 85(4):1031-1040): Milk-based proteins promote muscle protein accretion to a greater extent than do soy-based proteins when consumed after resistance exercise. The consumption of either milk or soy protein with resistance training promotes muscle mass maintenance and gains, but chronic consumption of milk proteins after resistance exercise likely supports a more rapid lean mass accrual.