Protein intake and Resistance Exercise

Resistance exercise by itself or when combined with eating proteins or amino acids can increase muscle protein growth. Over time of repeated exercise sessions, muscle mass and strength will increase. Furthermore, it has been shown that eating 20 grams of protein seems to be good for activating muscle growth processes.

Cow milk protein (20% whey and 80% casein) are rich sources of amino acids and contains all essential amino acids. Whey is absorbed by the body quickly, and casein is absorbed into the body slowly. One study tested whether one of two types of milk protein can help muscle growth during the time after a resistance exercise session. Seventeen healthy young men were tested to see whether drinking casein or whey drinks alone was superior in activating muscle growth after resistance exercise. Immediately after a heavy resistance training session (10 sets of 8 repetitions at 80% of maximal strength of one legged seated leg extension), the men were given either a casein or a whey drink. Muscle protein synthesis was measured for the six hours after finishing the drink.

Bottom line
While both drinks increased the muscle synthesis pathways, casein showed a more sustained growth synthesis for the hours after a weight training session. Either protein source can help with improving muscle growth after weight lifting, but the whole milk source might be better. Grab a glass of milk after exercise!

Source:
Reitelseder S, Agergaard J, Doessing S, Helmark IC, Lund P, Kristensen NB, Frystyk J, Flyvbjerg A, Schjerling P, van Hall G, Kjaer M, Holm L. Whey and casein labeled with L-[1-13C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion. Am J Physiol Endocrinol Metab. 2011 Jan;300(1):E231-42.