When it comes to the accretion of new muscle mass, protein intake is one of the primary variables to consider. Common discussions range from how much protein, protein source and bioavailability, refractory periods, and protein distribution.
This article will give a brief distillation of the currently available evidence and offer clear and concise recommendations to optimize protein distribution throughout the day and maximize your results.
Protein’s Role in the Body’s Functions
Protein serves various functions in the body, including but not limited to growth and maintenance of tissue,1 catalyze biochemical reactions,2 recovery from injury,3 and normal immune function.4
But of particular interest is its role in the synthesis of skeletal muscle. Muscle protein synthesis (MPS)5 is the process by which our bodies synthesize new muscle tissue. It’s a primary variable that galvanizes tissue remodeling.
Muscle protein breakdown (MPB)6 is an oppositional effect whereby muscle proteins degrade. This effect occurs through autophagy, and calpain, and the ubiquitin-proteasome systems.6
The balance between these two processes determined whether an individual will gain, maintain, or lose muscle mass.
- When the rate of MPS outpaces, MPB new muscle is accrued.
- When MPB outpaces MPS, muscle loss is observed.
Optimize Muscle Mass Gains
A 2019 paper7 by Iraki et al. established recommendations for naturalbodybuilders in the offseason. The authors reiterate what the larger body of evidence suggests: total protein intake is a more significant determining factor in developing new muscle mass than protein distribution. Currently, the research suggests a protein intake of 1.6-2.2 g/kg per day is sufficient to optimize muscular gains.7
However, when protein, calories, and any resistance exercise protocol are standardized, we still see a slight benefit when protein distribution is optimized 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 required within a protein feeding to stimulate MPS8 maximally.
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 exercise and feeding. Chronic application of these anabolic stimuli, as in B , results in muscle hypertrophy8.
Protein quality and bioavailability aren’t the subjects of this article, but generally, what’s observed is animal-based protein seems to be superior to plant-based proteins in most cases. However, several non-animal-based protein sources are high quality. If you’re interested in diving into this topic, you can get started by reading this paper, and this one, and this one. But I digress.
Assuming a sufficient quantity of protein is consumed, we maximize the MPS response (roughly 20-40 g). This response comes with what’s known as the “muscle full effect,” as described by Schoenfeld et al. in his 2018 paper.9 Essentially, once MPS is maximally stimulated, there is a refractory period by which MPS can’t be maximally stimulated again.
A 2017 paper10 by Kirksick, et al. found “Ingesting a 20-40 g protein dose (0.25-0.40 g/kg body mass/dose) of a high-quality source every three to 4 h appears to most favorably affect MPS rates when compared to other dietary patterns and is associated with improved body composition and performance outcomes.”10
So does protein distribution affect the accretion of muscle mass? Yes, it does, but the effect is small. However, I would caution against assuming that small is synonymous with not meaningful. Its value is relative to the individual and their goals.
Hypothetically speaking, a 1% increase in hypertrophy for an elite bodybuilder may be the difference between 1st and 5th place.
For the average individual, the extra effort may not be worth the relatively small effect on results. It’s up to each individual to determine whether the investment is worth it. Good luck!
References
1. Bosse JD, Dixon BM. “Dietary protein to maximize resistance training: a review and examination of protein spread and change theories.” J Int Soc Sports Nutr. 2012 Sep 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 intakes are associated with reduced length of stay: a comparison between Enhanced Recovery After Surgery (ERAS) and conventional care after elective colorectal surgery.” Am 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): 237-52.
5. P. J. Atherton and K. Smith, “Muscle protein synthesis in response to nutrition 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 Nutrition 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, “Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review.” Sports (Basel, Switzerland.), Vol. 7.7 154, 26 Jun 2019.
8. Burd NA, Tang JE, Moore DR, Phillips SM. “Exercise training and protein metabolism: influences of contraction, protein intake, and sex-based differences.” J Appl Physiol (1985). 2009 May;106(5):1692-701.
9. Schoenfeld, B.J., Aragon, A.A. “How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution.” J Int Soc Sports Nutr 15, 10 (2018).
10. Kerksick CM, Arent S, Schoenfeld 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. “International society of sports nutrition position stand: nutrient timing.” J Int Soc Sports Nutr. 2017 Aug 29;14:33.