Protein, Strength and Muscle Growth
iPB Protein Bite
Protein makes up greater than 80% of the dry weight of muscle. To build muscle strength and size, regular high-intensity and/or resistance exercise is required. Additionally, daily dietary protein requirements are elevated to provide the necessary amino acid building blocks for muscle protein manufacturing and adaptation, as well as changes in supporting tissue. Protein requirements approximate double base requirements and should be considered minimums. Higher protein intakes can minimize considerations related to protein types and timing, and protein nutrition can utilize the entire day (24 hours) to allow greater flexibility in training and diet schedules.
2018 iPB Consensus Statement on Protein Requirements for Development of Muscle Strength and Size
Based on the most up-to-date research and understanding of the issue, the International Protein Board presents its 2018 Consensus Statement on the protein requirements for the development of muscle strength and size:
"Protein serves as the basis of muscle structure and function, and requirements are elevated for the development of muscle strength and size in response to regular resistance exercise. Protein requirements approximately double the basic requirements standards should be considered the minimum dietary levels to maximize the adaptation efficiency."
iPB Survey 2018
Protein Requirements for the Development of Muscle Strength & Size
iPB SURVEY QUESTION: "The current dietary requirement for protein (e.g. ≈ 0.8 g/kg body weight or ≈46g women/56g men) stated by several countries is an adequate diet planning level for daily intake for people who are trying to improve muscle mass and/or strength through resistance training?"
iPB ANSWER SCORE: The iPB survey score is 4.82 with answers range from 1 = Strongly Agree to 5 = Strongly Disagree.
Proteins Requirements for the Development of Muscle Strength and Size
2018 iPB Brief
Skeletal muscle is among the most dynamic and adaptable tissue within the human body. One of the most remarkable features of skeletal muscle is its ability to adapt to perform better over time in response to regular related training. Routine resistance exercise training leads to increases in muscle strength and size, as well as maintenance of previous developments. These changes reflect small, transient increases in muscle protein which support the accretion of more appreciable muscle protein over time potentially leading to measurable gains in strength and size.1,2 Since protein-derived amino acids serve as building blocks for protein manufacturing, muscle development over time is dependent on sufficient availability of amino acids throughout.1 Said differently, high intensity, resistance training provides the stimulus for muscle to become stronger and/or more powerful, while dietary protein enables and creates efficiency of adaptation. Accordingly, protein requirements for people who engage in regular resistance training approximate double the RDA (Recommended Dietary Allowances) in the US and Canada and similar standards around the world.3
Muscle Protein Balance
Muscle protein is dynamic and always in a constant state of counterbalancing processes of muscle protein synthesis (MPS) and muscle protein breakdown (MPB).1,3-9 These processes are generally different, yet relatedly influenced by both training and protein-based nutrition. Muscle protein not only includes the structural and functional proteins of contraction (e.g. myosin, actin) but also enzymes, receptors, transporters and pumps as well as connective tissue proteins. Thus, the relative processes of MPS and MPB allow muscle to adapt on an acute, daily and long-term basis based in nutritional and metabolic state as well as in response exercise training.
In generally, the turnover of skeletal muscle proteins is regular to the extent that 1%–2% of proteins are synthesized and broken down each day.10 Muscle protein balance in a fasting state (e.g. > 8 hours) favors MPB as muscle proteins become a source of amino acids to supply on-going MPS. Oppositely, the consumption of adequate protein drives the reversal of this imbalance thereby augments MPS while MPB and promoting a net positive muscle protein balance.4-6 Protein manufacturing increases in muscle in response to resistance exercise and can remain elevated for more than 24 hours, especially earlier in a training program.1,4,11
Consumption of protein, either as food or supplement, leads to an elevation of plasma amino acid levels. The rate, length and degree of the elevation is largely dependent upon protein type, level and the co-consumption of other nutrients that can influence digestion and absorption, as well as tissue uptake and application.1,12-14 Elevated amino acid availability, via protein or supplement consumption, will support the combined effects of training and nutrition on elevated MPS greater than either alone. Plus, the additional benefit of protein on lowering MPB creates the positive differential and in turn net positive muscle protein balance.
Meal and Daily Protein Recommendations
Meal requirements (minimum thresholds) and recommendation for protein are often stated as 1) absolute gram amounts or 2) grams per kilogram body weight or fat free mass (FFM). In general, meal requirements for protein to achieve minimum thresholds to significantly elevate MPS of at least 20-25 grams or approximately 0.3 grams per kilogram body weight of complete protein for men. However, caution is necessary if trying to use this level as a guiding target level for meal planning for the following reasons. First, while these levels address a lower threshold level, whereby MPS is elevated and MPB reduced in a meaningful manner, the benefits on either side of net protein balance may not achieve its fullest potential. For instance, higher protein might be needed to achieve a greater response to resistance training involving multiple muscle groups especially when protein intake is minimized in the hours prior.9 Another important reason is that multiple meals daily only having 20-25 grams of protein is likely not to achieve recommendations for daily protein for people who train to build strength and size.
Professional associations such as the American College of Sports Medicine (ACSM) and the International Society of Sports Nutrition (ISSN) recommend 1.5-2.0 and 1.4 to 2.0 grams of protein per kilogram body weight daily, respectively.15,16 Thus, the midpoint of would approximate 1.75 grams per kilogram body weight daily, which for a 190lb male would approximate 150 grams. Split over five meals of consistent nutritional values, this would equate to food and/or supplement delivering at least 30 grams of protein per meal. More practical recommendations would be to strive for at least 0.3 to 0.6 grams of protein per kilogram body weight at meals in a strategic manner to ensure daily targets.
Ensuring higher protein intake throughout the day begins to reduce considerations of protein timing as well as differences in rates of digestion and/or potency kinetics and essential amino acids, inclusive of leucine which is a principle enhancer of protein synthesis signaling pathways.17,18 It is also important to understand that protein digestion, absorption and the impact on MPS and MPB are similar overnight as during waking hours.19,20 This opens up the entire 24 hours of the day to ensure higher protein demands to create an efficient accretion of body protein in response to resistance training. This might be especially important for people who train in the evening.
In closing, based on decades of research and understanding regular resistance exercise promotes adaptation in muscle tissue leading to increases or maintenance of greater strength and/or mass. Protein requirements are elevated to supply the necessary building blocks for protein manufacturing including proteins involved in muscle contraction, as well as connective tissue and other structural and functional muscle protein. Basic dietary protein needs would be approximately double existing RDAs and similar standards around the world. Furthermore, the entire day can serve to ensure adequate protein intake.
- Wildman REC, Miller B, Wilborn C, Campbell B, Arent S. Protein, In: Sports and Fitness Nutrition (3rd ed), Kendall Hunt Publishing, 2018. (Link to Sports and Fitness Nutrition, 2018)
- Medeiros DM, Wildman REC. Protein, In: Advanced Human Nutrition (4th ed), Jones & Bartlett Learning, 2018. (Link to Advanced Human Nutrition, 2018)
- Institute of Medicine. 2005. Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Protein and Amino Acids (Macronutrients). The National Academies Press, Washington, DC, USA. (access the report)
- Phillips, S. M., Hartman, J. W., & Wilkinson, S. B. (2005). Dietary Protein to Support Anabolism with Resistance Exercise in Young Men. Journal of the American College of Nutrition,24(2). (Access the Research Study)
- Pasiakos SM, Vislocky LM, Carbone JW, Altieri N, Konopelski K, Freake HC, Anderson JM, Ferrando AA, Wolfe RR, Rodriguez NR. Acute Energy Deprivation Affects Skeletal Muscle Protein Synthesis and Associated Intracellular Signaling Proteins in Physically Active Adults, Journal of Nutrition; 2010, 140 (4): 1. (Access the study)
- Witard OC, Jackman SR, Breen L, Smith K, Selby A, Tipton KD. Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. American Journal of Clinical Nutrition; 2014, 99 (1): 86–95. (Access the Research Study)
- Witard O, Wardle SL, Macnaughton LS, Hodgson AB, Tipton KD. Protein Considerations for Optimizing Skeletal Muscle Mass in Healthy Young and Older Adults. Nutrients; 2016, 8(4): 181. (Access the Research Study)
- Moore DR, Tang JE, Burd NA, Rerecich T, Tarnopolsky MA, Phillips SM. Differential stimulation of myofibrillar and sarcoplasmic protein synthesis with protein ingestion at rest and after resistance exercise. Journal of Physiology; 2009, 587(4): 897–904. (Access the Research Study)
- Macnaughton LS, Wardle SL, Witard, OC, McGlory, C., Hamilton, D. L., Jeromson, S, Tipton KD. The response of muscle protein synthesis following whole‐body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiological Reports; 2016, 4(15): e12893. (Access the Research Study)
- Welle S, Thornton C, Statt M, McHenry B. Postprandial myofibrillar and whole-body protein synthesis in young and old human subjects. American Journal of Physiology; 1994, 267, E599–E604. (Access the Research Abstract)
- MacDougall JD, Gibala MJ, Tarnopolsky MA, MacDonald JR, Interisano SA, Yarasheski KE. The time course for elevated muscle protein synthesis following heavy resistance exercise. Canadian Journal of Applied Physiology; 1995; 20(4):480–6. (Access the Research Abstract)
- Tang, J. E., Moore, D. R., Kujbida, G. W., Tarnopolsky, M. A., & Phillips, S. M. (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. Journal of Applied Physiology, 107(3), 987-992. (Access the Research Study)
- Dangin M, Boirie Y, Garcia-Rodenas C, Gachon P, Fauquant J, Callier P, Ballevre O, Beaufrere B. The digestion rate of protein is an independent regulating factor of postprandial protein retention. Am J Physiol Endocrinol Metab. 2001 Feb, 280(2):E340-8. (Access the Research Study)
- Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL,. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci USA. 1997; 94:14930–5. (Access the Research Study)
- Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016 Mar;48(3):543-68. (Access the ACSM/AND/DC Position Stand)
- Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, Purpura M, Ziegenfuss TN, Ferrando AA, Arent SM, Smith-Ryan AE, Stout JR, Arciero PJ, Ormsbee MJ, Taylor LW, Wilborn CD, Kalman DS, Kreider RB, Willoughby DS, Hoffman JR, Krzykowski JL, Antonio J. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017 Jun 20;14:20. (Access the ISSN Position Stand)
- Norton LE, Layman DK, Bunpo P, Anthony TG, Brana DV, Garlick PJ. The leucine content of a complete meal directs peak activation but not duration of skeletal muscle protein synthesis and mammalian target of rapamycin signaling in rats. J Nutr 2009; 139:1103–1109. (access the study)
- Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013 Dec 3;10(1):53. (Access the Research Study)
- Res PT, Groen B, Pennings B, Beelen M, Wallis GA, Gijsen AP, Senden JM, VAN Loon LJ. Protein ingestion before sleep improves postexercise overnight recovery. Med Sci Sports Exerc. 2012 Aug;44(8):1560-9. (Access the Research Study)
- Snijders T, Res PT, Smeets JS, van Vliet S, van Kranenburg J, Maase K, Kies AK, Verdijk LB, van Loon LJ. Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men. Journal of Nutrition. 2015 Jun;145(6):1178-84. (Access the Research Study)
Interview with Dr Stu Phillips on Muscle Development and Role of Protein. This is a printable Q/A article format and goes beyond protein to discuss other macronutrients as well.
Dr. Stuart Phillips answers questions in Muscle Hypertrophy and Sports Nutrition. Discussion includes the role of training and protein on muscle development, resistance load, etc.
Dr Kevin Tipton provides a brief answer as to whether Meat Protein is a Good Stimulator of Muscle Protein Building. (International Olympic Committee (IOC) Brief)
Dr Oliver Witard provides a brief answer as to the Differences between Different Types of Protein Stimulation of Muscle Protein Building following exercise. (International Olympic Committee (IOC) Brief)
Dr Stu Phillips overviews Protein Requirements for Anabolism. Protein requirements from determination to application are discussed and the strength of support for higher requirements for athletes.