Wednesday, December 4, 2013

Muscle Protein Synthesis: Protein Consumption

                You may reach for that protein shake after your workout, but what for? Many are aware of the potent effects that resistant exercise has on muscle protein synthesis. And when combined with protein post-workout, muscle protein synthesis has been shown to be stimulated even further. But, when should you consume your protein, from what protein source, and how much?

                So, does this mean the infamous half-hour “anabolic window” is true? Well, not necessarily. The Sports Science Exchange, looked at several chronic studies. The chronic training studies suggest the “window” during which protein should be consumed is likely less than 2 hours following exercise in order to support greater increases in lean body mass and muscle hypertrophy in younger adults.1 Whereas in one acute study, it was translated to consume a source of protein within a 1 hour after exercise to support greater hypertrophy with resistance training.1

                What about the protein source? Chances are your choice is a whey protein powder. But, do whole milk proteins or soy protein have a greater impact on muscle protein synthesis? Well, according to the Sports Science Exchange, both whole milk proteins and soy proteins in isolation or as a supplement were able to support muscle protein growth after a weight lifting session. Concerning whole milk proteins, it was found that whole milk was superior to fat-free fluid milk in the ability to build muscle after exercise.1 Topping all however was a rapidly digested whey protein hydrolysate. The Journal of Applied Physiology found the whey protein hydrolysate to be more effective than both soy and micellar casein – the form of casein in milk – in stimulating both muscle protein synthesis at rest and following resistance exercise.  The correlation was the peak leucine – a branched chain amino acid – concentration.2

                Alright so we know when to take the protein and what protein source is optimal for muscle protein synthesis, but how much protein is necessary? The muscle protein response in both young and older people was found to plateau at approximately 10 grams of indispensable or essential amino acids.3 Interestingly, as muscle protein synthesis plateaus, the “extra” amino acids are simply being burned for fuel.1 Thus, the idea of “more is always better,” is certainly not applicable to large quantities of amino acids and/or protein in the hopes of induced or accelerated gains in muscle mass. In contrast, consuming 20 grams of high-quality protein – such as whey protein – will optimally maximize the stimulus of muscle protein synthesis.1 Also throughout the day, it is a good idea to consume protein at spaced intervals to maximize the anabolic response – about 0.25 g protein per kg of body mass per meal.1 Of course, larger athletes may require more protein in order to maximize muscle protein synthesis in comparison to smaller athletes. Aim for 1.2-1.6 grams of protein per kg a day. This amount is adequate and more than required by the majority of athletes.1 Talk with your Sports Dietitian to assess your individual needs based on your exercise regimen and sport.

Gavin Van De Walle is an ISSA Certified Fitness Trainer, a NANBF Natural Competitive bodybuilder, and a dietetic student at South Dakota State University. Following graduation, Gavin will pursue his Ph.D. in nutritional sciences while aiming to make a positive impact on the over well-being and nutritional status of the American people along the way.

1.       Stuart M. Phillips. Protein consumption and resistance exercise: maximizing anabolic potential. Sports Science Exchange. (2013) Vol. 26. No. 107, 1.5.
2.       Tang, J.E., D.R. Moore, G.W Kujibida, M.A. Tarnopolsky, and S.M Phillips (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J. Appl. Physiol. 107:               987-992.

3.       Cuthbertson, D., K. Smith, J. Babraj, G. Leese, T. Waddell, P, Atherton, H. Wackerhage, P.M. Taylor, and M.J. Rennie (2005). Anabolic signaling deficits underlie amino acid resistance of wasting, aging muscle. FASEB J. 19: 422-424.