Protein and the Endurance Athlete: Part One, What is Protein Anyway?

Protein for the endurance athlete is an essential ingredient for success. Learn what this macronutrient does and how to use it.

Protein and the Endurance Athlete Part 1: What is Protein Anyway?

This is a two-part series for protein and the endurance athlete. This article will provide the theoretical framework of protein for athletes, and part two will discuss the practical application of meeting your protein needs through your diet.

While carbohydrates are king of fueling performance, protein comes into play with post-training recovery. It’s important to understand the role that protein can play and how it can support your body as you work towards your athletic goals.

Why Protein Matters

Protein consists of amino acids and has multiple roles in the body:

  • Protein is an essential macronutrient that provides calories and supports building and repairing muscle.
  • Assists in regulating hunger by providing satiety. Including adequate protein at meals and snacks helps curb your appetite for longer.  
  • It helps to repair and build tissues such as skin, nails, bones and hair. 
  • Allows metabolic reactions to take place and coordinates bodily functions by producing hormones, enzymes and other chemicals.
  • Controls fluid volume and maintains water and pH balance. 

How Much Protein do Athletes Need?

Endurance athletes have higher protein needs than those that aren’t actively exercising. The latest recommendations from the International Society of Sports Nutrition are that athletes should be getting between 1.4-2.0 grams per kg body weight (0.63-0.9 g/lb). 

Ideally, you’ll want to adjust protein intake to reflect rest, low-volume and high-volume endurance training phases, with the heavier the training volume the higher protein intake to support muscle recovery and minimize muscle loss.


It’s best to consume protein consistently throughout the day to supply your body with a steady source of amino acids. This will optimize muscle recovery, repair and growth, while helping regulate your appetite.

Post-workout, aim to consume 15-25 grams of protein within 30-60 minutes to take advantage of the body being primed to start the recovery process. It’s important to also consume carbohydrates with protein as the release of insulin increases amino acid uptake into muscle and suppresses muscle breakdown.

Protein Quality and Types

Nutrition from real food has consistently been shown to offer the best benefits when compared to the nutrition received from supplements. For most athletes they can meet their daily protein needs through food alone, including vegetarian diets.

Overall, the research has shown that animal-based proteins, such as meats, poultry, fish, seafood, eggs and dairy contain the highest amount of essential amino acids to support building and repairing lean muscle. 

Whole plant foods also provide protein and good sources include beans, peas, lentils, whole grains, nuts, seeds and soy such as tofu and tempeh. With most plant-based protein sources, you’ll need to pair up foods to make sure you’re getting a complete blend of essential amino acids. 

The Science Behind Protein

There are three branched-chain amino acids (BCAAS): isoleucine, leucine and valine. BCAAS are unique as they are particularly effective and efficient at supporting muscle growth compared to other amino acids. Leucine specifically may be the most important BCAA of all, as its role is to signal the body that amino acids are available and stimulate the muscle to start repairing and rebuilding muscle.  

Sources of leucine include beef, poultry, eggs, salmon, tuna, whey (dairy), beans, oats, tempeh/tofu, edamame and pumpkin seeds. Focus on getting leucine-rich foods throughout your day instead of leucine or BCAA supplements. Not only will you save money, but those foods will offer other beneficial nutrition as well. 

Protein powders are a convenient option for athletes to supplement protein for training. It’s important to find protein options that are right for you and deliver the best nutrition for your body to recover effectively and efficiently from training.