Does Protein Distribution Effect Muscle Mass?
When it comes to gaining new muscle mass, protein intake is one of the most important variables to consider. Frequent discussions range from the amount of protein, protein source and bioavailability to refractory periods and protein distribution.
This article gives a brief overview of the data currently available and provides clear and concise recommendations on how to optimize protein distribution throughout the day and maximize your results.
The role of protein in the functions of the body
Protein fulfills various functions in the body including, but not limited to, tissue growth and maintenance, 1 catalysis of biochemical reactions, 2 recovery from injury, 3 and normal immune function. 4
Of particular interest, however, is its role in the synthesis of skeletal muscles. Muscle Protein Synthesis (MPS) 5 is the process by which our bodies synthesize new muscle tissue. This is a primary variable that speeds tissue remodeling.
Muscle protein breakdown (MPB) 6 is an oppositional effect in which muscle proteins are broken down. This effect occurs through autophagy, calpain, and the ubiquitin proteasome systems. 6
The balance between these two processes determines whether a person gains, maintains, or loses muscle mass.
- When the rate of MPS exceeds MPB, new muscle is accumulated.
- When MPB outperforms MPS, muscle loss is observed.
Optimize muscle building
A 20197 paper by Iraki et al. established recommendations for natural bodybuilders in the off-season.
The authors reiterate what the greater body of evidence suggests: Total protein intake is a more important determinant of new muscle mass development than protein distribution.
Currently, research suggests that a protein intake of 1.6 to 2.2 g / kg per day is enough to optimize muscle gain
However, with protein, calories, and any resistance training protocol standardized, we still see a slight benefit in optimizing protein distribution throughout the day.
One of the more obvious reasons for this is the refractory period of MPS. The leucine threshold describes the amount of leucine that is required within a protein supply to maximally stimulate MPS8.
A: Changes in muscle protein synthesis (MPS) and muscle protein breakdown (MPB) in response to feeding (i.e. amino acids). B: Changes in MPS and MPB in response to resistance training and feeding. The chronic use of these anabolic stimuli as in B leads to muscle hypertrophy8.
Protein quality and bioavailability are beyond the scope of this article, but in general it appears that animal protein appears to be superior to vegetable proteins in most cases.
However, some non-animal sources of protein are of high quality. If you want to dig into this topic, read this and this and this document first. But I digress.
Assuming a sufficient amount of protein is consumed, we will maximize the MPS response (approximately 20-40 g). This reaction comes with the so-called "muscle-full effect", as described by Schönfeld et al. in his work of 2018.9
Once MPS is maximally stimulated, there is essentially a refractory period during which MPS cannot be maximally stimulated again.
A 2017 paper10 by Kirksick et al. found “Taking a 20-40 g protein dose (0.25-0.40 g / kg body mass / dose) from a high-quality source every three to four hours seems to have the most favorable influence on MPS rates compared to other eating habits associated improved body composition and performance results. “10
Does protein distribution affect muscle mass accumulation? Yes, but the effect is small. However, I would caution against assuming that small is not meaningful. Its worth is relative to the individual and their goals.
Hypothetically, a 1% increase in hypertrophy for an elite bodybuilder can mean the difference between 1st and 5th place.
For the average person, the extra effort may not be worth the relatively small impact on results. It is up to each individual to decide whether the investment is worthwhile. Good luck!
References
1. Bosses JD, Dixon BM. "Dietary Protein for Maximizing Strength Training: A Review and Examination of Protein Spread and Theories of Change." J Int Soc Sports Nutr. 2012, September 8; 9 (1): 42.
2. Cooper GM. "The Central Role of Enzymes as Biological Catalysts." The cell: a molecular approach. 2nd Edition. Sunderland (MA): Sinauer Associates; 2000.
3. Yeung SE, Hilkewich L., Gillis C., Heine JA, Fenton TR. "Protein intake is associated with reduced length of stay: a comparison between improved recovery after surgery (ERAS) and conventional care after elective colorectal surgery." At J Clin Nutr. 2017 Jul; 106 (1): 44- 51.
4. Li P, Yin YL, Li D, Kim SW, Wu G. "Amino acids and immune function." Br J Nutr. 2007 Aug; 98 (2): 237-23. 52.
5. P.J. Atherton and K. Smith, "Muscle Protein Synthesis in Response to Diet and Exercise." The Journal of Physiology, Vol. 59-5, 1049-57.
6. Kevin D. Tipton, D. Lee Hamilton, Iain J. Gallagher, "Assessing the Role of Muscle Protein Breakdown in Response to Diet and Exercise in Humans." Sports medicine (Aukland, N.Z.). Vol 48, 2018. Suppl 1, 53-64.
7. Juma Iraki, Peter Fitschen, Sergio Espinar, and Eric Helms, "Diet Recommendations for Bodybuilders in the Off-Season: A Narrative Overview." Sport (Basel, Switzerland.), Vol. 7,7 154, June 26, 2019.
8. Burd NA, Tang JE, Moore DR, Phillips SM. "Exercise Training and Protein Metabolism: Influences of Contraction, Protein Intake, and Gender Differences." J Appl Physiol (1985). 2009 May; 106 (5): 1692-1. 701
9. Schönfeld, B.J., Aragon, A.A. "How Much Protein Can the Body Use to Build Muscle in a Single Meal? Effects on Daily Protein Distribution." J Int Soc Sports Nutr 15, 10 (2018).
10. Kerksick CM, Arent S., Schönfeld BJ, Stout JR, Campbell B., Wilborn CD, Taylor L., Kalman D., Smith-Ryan AE, Kreider RB, Willoughby D., Arciero PJ, VanDusseldorp TA, Ormsbee MJ , Wildman R., Greenwood M, Ziegenfuss TN, Aragon AA, Antonio J. "State of the International Society for Sports Nutrition: Nutrient Timing." J Int Soc Sports Nutr. 2017, August 29; 14:33.
