Dr. Paul Henning concludes his article looking closely at the best proteins for muscle growth…
The role of leucine and other amino acids
There is no doubt that a high quality protein source enhances acute resistance exercise induced muscle protein synthesis and net protein balance.
Moreover, acute net protein balance after exercise and essential amino acid ingestion reflects 24-hour net protein balance  and there is evidence for protein to augment long-term lean body mass gains to a greater degree than placebo or carbohydrate.
Based on current literature, isolated or mixed milk proteins seem to have the most potential to facilitate muscle growth compared with other proteins.
Both components of milk protein (whey and casein) are high in leucine and other essential amino acids, but only whey seems to effectively enhance acute post-workout muscle protein synthesis due to its fast absorbable characteristics .
Adding leucine or other amino acids to a sufficient amount of protein, which is already high in essential amino acid, doesn’t seem to further augment skeletal muscle growth .
However, if the amount of high-quality protein and leucine is below what seems to be the sufficient amount (20g and 1-1.7g, respectively), adding essential amino acids or leucine could help get the optimal, early response after resistance exercise.
Key take-home points:
After a thorough review of recent research, below are the key take practical points that you can use to apply to your nutrient timing around your intense resistance training and cardio workouts.
a) Most of the results from the research suggest ingesting milk protein (whey/casein) directly before or after resistance exercise is advantageous for individuals interested in optimizing skeletal muscle hypertrophy.
b) The available literature indicates that a combination of fast and slow acting milk proteins (i.e., whey and casein) could provide the most perpetual anabolic effects.
c) The exact amount that should be ingested is dependent on the quality of the protein and its content of essential amino acids, specifically leucine, with 1-1.7g of leucine appearing to be optimal to facilitate muscle protein accretion.
d) Approximately 20g of a milk protein followed by a similar amount ~1 hour later, or alternatively, ~40g in a single bolus feeding seems to maximize the acute muscle protein synthesis response after resistance exercise, as well as long-term muscle growth.
e) Exceeding the amounts above may only be necessary if a lower quality protein (i.e. plant-based protein) is chosen.
I hope this has given you valuable information regarding the best proteins for muscle growth.
Connect here with WatchFit Expert Dr. Paul Henning
PhD, CSCS, CISSN
10) Tipton, K.D., et al., Acute response of net muscle protein balance reflects 24-h balance after exercise and amino acid ingestion.Am J Physiol Endocrinol Metab, 2003. 284(1): p. E76-89.
11) Tang, J.E., et al., 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 (1985), 2009. 107(3): p. 987-92.
12) Herda, A.A., et al., Muscle performance, size, and safety responses after eight weeks of resistance training and protein supplementation: a randomized, double-blinded, placebo-controlled clinical trial.J Strength Cond Res, 2013. 27(11): p. 3091-100.