Protein Power: The Endurance Athlete’s Guide to Optimal Protein Intake

Protein, one of three macronutrients, is an important component of an endurance athlete’s diet. This nutrient plays a key role in building muscle, rebuilding damaged tissues, improving immune function, stabilizing blood sugar, producing hemoglobin, and more. Protein intake needs for endurance athletes is higher than the general population due to the demands exercise places on the body. 

Role Of Protein In Endurance Training

After a particularly hard effort, an athlete’s muscles are full of microtears. These microtears must be rebuilt in order for the athlete to fully recover and come back stronger. Proteins repair these damaged muscles, tissues, and tendons. This allows endurance athletes to recover more quickly, which indirectly improves endurance performance. Protein’s role in immune function may also allow the athlete to have more consistent training in the absence of illness. 

Athletes should aim to have a protein source with each meal and snack they consume. Prioritizing consumption of protein improves the overall balance of meals and snacks for athletes. Balanced meals and snacks improve blood sugar regulation, which is likewise tied to improved metabolic efficiency. Metabolically efficient athletes are better at using alternative fuel sources to carbohydrate (aka fats and proteins) during endurance exercise for energy. 

Protein Sources

Protein sources can be placed into 2 categories: quality proteins and “less” quality proteins. Quality proteins include all nine essential amino acids, and “less” quality proteins contain some, but not all of the nine essential amino acids. Generally speaking, meat and dairy sources of protein fall into the “quality” and plant-based proteins into the “less” quality category. 

Athletes benefit most from consuming quality sources of protein, specifically for the amino acid leucine. Some great options for this include: Greek yogurt, cheese sticks, cow’s milk (regular or lactose-free), cottage cheese, whey protein powder, lean ground turkey, chicken breast, lean ground beef, and salmon. 

Combining “less” quality proteins, or simply including a variety of these proteins in your diet will allow athletes to get all of the essential amino acids. Some of these combinations include: brown rice and black beans, whole grain toast with peanut butter, or a salad topped with chickpeas and sunflower seeds. 

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Timing

Post-exercise protein intake is the most important concept to focus on in terms of protein intake timing. Muscle protein synthesis is the key force that promotes the building of new muscle and muscle repair. This process is turned “on” most effectively when enough protein is eaten close to completion of exercise. The exact duration of this “window” is debatable, but I typically recommend to my clients to get something in as soon as possible, but no longer than 90 minutes following the completion of exercise. 

Consuming protein before or during exercise has no concrete effect on endurance athlete performance. Some research suggests that during-exercise protein intake can improve the rate of muscle protein breakdown, but evidence is limited. 

Quantities For Enhanced Recovery And Muscle Maintenance

Daily protein requirements vary by age, gender, and activity type. Some evidence suggests increased protein intake for athletes over the age of 40 in order to prevent muscle loss due to aging. There are no concrete guidelines in this area yet, but here are some rough guidelines or suggestions to follow. 

Endurance trained athletes

• Males & females <40: 1.2-1.4 g protein per day
• Males & females >40: 1.5-1.7 g protein per day

Endurance trained athletes who also lift

• Males & females <40: 1.4-1.6 g protein per day
• Males & females >40: 1.7-2.0 g protein per day

*needs will increase for females during time periods where they are pregnant or breastfeeding by roughly 0.3 grams per kilogram of body weight per day

Conclusion

Eating enough protein as an endurance athlete will benefit an athlete’s recovery from hard efforts, ability to stay injury and sickness-free, thus improving the chances for optimal endurance performance. Timing protein intake to be consumed as soon as possible post-exercise is helpful for optimizing the impact protein can have for the athlete. Protein intake for endurance athletes will change throughout the lifespan as the effects of aging kick in.

References

Aragon AA, Schoenfeld BJ. Nutrient timing revisited: is there a post-exercise anabolic window? J Int Soc Sports Nutr. 2013 Jan 29;10(1):5. doi: 10.1186/1550-2783-10-5. PMID: 23360586; PMCID: PMC3577439.

Moore DR. Protein Requirements for Master Athletes: Just Older Versions of Their Younger Selves. Sports Med. 2021 Sep;51(Suppl 1):13-30. doi: 10.1007/s40279-021-01510-0. Epub 2021 Sep 13. PMID: 34515969; PMCID: PMC8566396.

Kominiarek MA, Rajan P. Nutrition Recommendations in Pregnancy and Lactation. Med Clin North Am. 2016 Nov;100(6):1199-1215. doi: 10.1016/j.mcna.2016.06.004. PMID: 27745590; PMCID: PMC5104202.

Vitale K, Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019 Jun 7;11(6):1289. doi: 10.3390/nu11061289. PMID: 31181616; PMCID: PMC6628334.

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