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Protein and Performance

Updated: Jul 23, 2023

Protein is the building block of muscle, so naturally, it’s an important part of an athlete’s diet. In this article, we’ll disclose why it’s important and how much to consume to ensure optimal strength and muscle gains.

Protein is probably the number one thing that athletes think about when it comes to nutrition. Unsurprisingly, about one in four athletes use protein powder supplements (1). It’s no wonder—protein has become a buzzword that’s slapped on to many products in the supermarket. But, as an athlete, why is it important and how much do you need?

Protein Basics

Protein is a macronutrient, like carbohydrates and fats. However, protein is different as it’s not usually used as a fuel. Rather, it’s important in the repair and building of muscle and other tissues (e.g., connective tissue, bone, etc.).

Protein is made up of strings of individual building blocks, called amino acids. Some of which we have to get from our diet (essential), others our body can make (non-essential). If a food is high in essential amino acids, and if the protein is very bioavailable (digestible) it’s called a high-quality” protein.

Of the essential amino acids, leucine is of particular importance for athletes as leucine triggers muscle protein synthesis (MPS), kicking off the process of repairing and building muscle. However, leucine (and protein) are not the only triggers of MPS: exercise is a greater trigger, raising MPS for ~24 hours after exercise (2). This explains why exercise can improve strength and muscle mass in the absence of a high protein intake, and is the most important determinant of performance improvements.

Why Protein is Important

In a 2018 meta-analysis of 49 protein supplementation studies, authors found that protein supplementation significantly increased one-rep max strength and fat-free (lean) mass, by ~2.5 kg and ~0.3 kg, respectively (3). However, once baseline protein intake was ~1.6 g/kg/d, more protein (in the form of supplements) had no further (significant) effect on these outcomes. This would suggest that ~1.6 g/kg of protein per day is what athletes should consume to optimise strength and muscle gains.

In addition, a new and even bigger meta-analysis published earlier this year has repeated these findings (4). Specifically, this study included 74 randomised controlled trials (RCTs), finding that on average, protein supplementation significantly increases lean mass by ~0.6 kg more than placebo/controls not consuming protein supplements, and improves upper and lower body strength in those engaged in resistance training. However, the majority (~80%) of studies had participants who were consuming moderately high levels of protein (~1.2 g/kg/d) to begin with, meaning that the effects we are seeing may be less pronounced than if you go from a low protein (e.g., < 0.8 g/kg/d) diet to a higher protein diet (e.g., ~1.6 g/kg/d).

You might be thinking, increasing lean mass by ~0.3–0.6 kg isn’t that much. I would tend to agree—especially considering that lean mass includes more than just muscle tissue (e.g., bone, connective tissue, water, etc.). However, these effects are being observed in trials that tend to be conducted over a relatively short period of time (8–12 weeks). As most athletes have careers lasting many years, these performance improvements may accumulate over time.

Protein Recommendations

The Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine recommend a daily protein intake of 1.2–2.0 g/kg of protein for athletes (2). This can range depending on the exercise or sport type:

  • Endurance athletes, e.g., long-distance runners: 1.2–1.6 g/kg/d

  • Mixed sport athletes, e.g., footballers: 1.4–1.8 g/kg/d

  • Strength/power sport athletes, e.g., powerlifters: 1.6–2.0 g/kg/d

These are general, but prudent, recommendations. One caveat is for athletes in an aggressive fat loss phase, e.g., bodybuilders. When calories are low and energy expenditure is high, it may be wise to consume a large amount of protein (up to ~3 g/kg/d), as this may reduce the likelihood that you’ll lose muscle mass when aiming to lose fat mass (5).

Other Protein Considerations

There are a couple of common questions that come up about protein and performance that we’ll cover here:

Q: Is plant protein inferior to animal protein?

A: At low intakes of protein, animal protein may be more anabolic than plant protein, meaning it can stimulate greater MPS responses and potentially lead to greater gains in muscle mass over time. But, this effect seems to disappear once the recommended amount of total protein for athletes is consumed (~1.6 g/kg/d). To support this, a recent RCT of young male vegans and omnivores eating 1.6 g/kg/d showed no significant differences in muscle or strength gain between groups after 12 weeks of resistance training (6).

Q: Do I need to eat protein within 30 minutes of exercise?

A: This 30-minute "window of anabolic opportunity" is less like a window and more like a barn door, meaning that there’s no rush to get the food in straight away. But eating within a couple of hours is a good idea.

Q: How many protein-rich meals should I eat per day?

A: While the most important consideration is ensuring that you’re eating enough total protein, if you want to further optimise, eating ~0.3–0.4 grams every 2–3 hours or so is likely optimal for stimulating MPS, and in turn, for gaining strength and muscle mass.

Now that you have levelled up your nutrition knowledge, level up on the pitch, too. Contact [email protected] to get started.

That’s all for this week!

Patrick Elliott, BSc, MPH

Health and Nutrition Science Communication Officer at Training121

Founder of Just Health — IG:

Health Disclaimer: this article is for informational and educational purposes only, and is not a substitute for professional advice. For health advice, speak to a physician or other qualified health-care professional, and for nutrition advice, speak to a qualified nutrition professional (e.g., registered dietitian). The use of information on this site is solely at your own risk.


(1) Knapik JJ, Steelman RA, Hoedebecke SS, Austin KG, Farina EK, Lieberman HR. Prevalence of Dietary Supplement Use by Athletes: Systematic Review and Meta-Analysis. Sports Med. 2016 Jan;46(1):103-23. Available at:

(2) Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016;116(3):501-28. Available at:

(3) Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, Aragon AA, Devries MC, Banfield L, Krieger JW, Phillips SM. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018 Mar;52(6):376-84. Available at:

(4) Nunes EA, Colenso-Semple L, McKellar SR, et al. Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults. J Cachexia Sarcopenia Muscle. 2022;13(2):795-810. Available at:

(5) Aragon AA, Schoenfeld BJ, Wildman R, et al. International society of sports nutrition position stand: diets and body composition. J Int Soc Sports Nutr. 2017;14:16. Available at:

(6) Hevia-Larraín V, Gualano B, Longobardi I, et al. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. Sports Med. 2021;51(6):1317-30. Available at:

Technical Terms

Macronutrients: These are nutrients that are required in large amounts, and can be energy-providing, i.e., carbohydrates, fat, protein, and alcohol, or non-energy providing, i.e., water.

Amino acids: These are the building blocks of protein, that when strung together, form proteins.

Essential: In the context of human nutrition, essential nutrients must be obtained through diet, i.e., our bodies cannot make them.

Bioavailable: This refers to how much of a nutrient our body can absorb, so a bioavailable nutrient means a well-absorbed nutrient.

High-quality protein: These are proteins high in essential amino acids that are highly digestible, or bioavailable. Examples: meats, eggs, fish, milk, soy milk, tofu, Quorn (mycoprotein) products, protein powders, etc.

Leucine: This is the most important amino acid for stimulating MPS. However, there is a threshold effect here: any more than ~2–3 grams of leucine per meal will not further enhance MPS.

Muscle protein synthesis (MPS): The process where muscle is built and repaired in the body.

Meta-analyses: These are a type of study that combines the results of a number of other studies that look at the same thing, and produces a summative estimate of the effect or association of what’s being studied. For example, a meta-analysis of five studies looking at smoking and lung cancer would combine the results from all five studies into one overall result, with the intention of providing a better estimate of the true effect of smoking on lung cancer.

Randomised controlled trials: Also known as RCTs, these are a type of intervention study where a group of recruited individuals are randomly assigned to groups within a study. The rationale for randomisation is to reduce bias, that is, to evenly distribute among groups any factors that may influence (or bias) the result of interest. For example, if we have a group of 100 people who will either be given a multivitamin or placebo and followed for 10 years to see how many in each group dies, we would randomise so that each group is on average similar for factors like age, physical activity status, smoking status, and so on. If we didn't randomise, there's a greater chance that one group may end up being different enough from another group such that the results of the study may be biased, e.g., one group could have a lot more smokers or sedentary individuals, which would likely influence the outcome of interest (death).

Anabolic: This refers to the capacity of protein to be able to build muscle. The opposite term is catabolic: if something is catabolic it breaks something else down. Using muscle as an example, eating too few calories is a catabolic activity.

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