Protein and the Endurance Athlete

June 11, 2018

When most people think protein and athletes, they picture bodybuilders and strength athletes. However, protein is also important for endurance athletes. Here’s why and just exactly how much you need of it.

The role of protein

Our muscles contain numerous proteins (contractile, structural and metabolic proteins) that perform a variety of functions essential to everyday life and of course, exercise performance. Working together, they produce the energy and movement needed to help us perform.

Dietary protein from the foods we eat are digested and absorbed into the body as amino acids (the building blocks of protein). Since our bodies don’t store protein, this “pool” of amino acids, fueled by the amino acids we ingest from our diet, is continuously being used (among other things) for muscle protein synthesis (repairing and building new muscle tissue).

Protein and training adaptation

The stress of endurance exercise causes many of our muscle proteins to break down (protein degradation), a process that can of course be detrimental to training adaptation. However, exercise also creates a metabolic signal that tells our muscles to make new metabolic proteins in the mitochondria (the powerhouse of the muscle cells where oxygen and nutrients are converted into energy). The combination of exercise and adequate protein intake leads to the formation of new proteins which help our muscles meet the physical demands of the next training session. Our muscles synthesize new proteins after every training session, and these repeated bouts of muscle protein synthesis is the basis of how our muscles repair themselves and further adapt to the demands of training. The net result of all this is that our muscles contain more mitochondria and our exercise performance is significantly improved!

Since protein-rich foods and supplements are made up of the building blocks used to make new proteins in our muscles, for optimal training adaptation to occur, it is essential that we ingest them in close proximity to training.

Protein requirements for endurance athletes

Athletes generally need more protein than sedentary individuals. Current data on endurance athletes suggests that the optimal daily requirements for protein intake needed to support muscle repair, metabolic adaptation and protein turnover generally ranges from 1.2 to 1.4 g/kg/day. Intakes up to 2 g/kg/day may be indicated for shorter periods of intense training when energy intakes are higher and muscle recovery is crucial or during training periods designed to reduce body fat while preserving muscle mass. A 60 kg (~132 lb) athlete would thus generally need anywhere between 72 to 84 grams of protein per day or more depending on the objectives of the training plan.

Perhaps even more important than total daily protein intake is how protein intake is distributed throughout the day. Protein intake should be spaced evenly throughout the day and between meals and after workouts (~20 to 30 grams every 3-4 hours).

Within 60 minutes of exercise, it is recommended to consume 0.25 grams of protein per kg body weight; although ~20g has been shown to be adequate for most athletes. And don’t skip the carbs! Adding carbohydrate to your post exercise snack will further enhance training adaptation by reducing the degree of muscle protein breakdown, helps blunt the stress hormone response to exercise (positive for your immune system), and of course refuels glycogen stores post-exercise.  

Finally, emerging evidence shows that an important time to consume protein is before sleep, during which time amino acids can be delivered to muscles to maintain protein synthesis in the overnight period. So, eat a protein rich snack before bed, especially if you train in the evenings!


Protein sources

Protein is found in many different foods. Whether you follow a traditional diet, a vegetarian or vegan lifestyle, there are plenty of options to help you meet your daily protein requirements.

Protein sources list


Stephanie Jamain, M.Sc, RD, CSSD

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