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Performance Enhancing Supplements:
Part 4, Protein for the Endurance Athlete

By certified sports nutritionist Marcia Homer, MS, CSN

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Marcia Homer writes:

As an endurance athlete, most of my life has been about the pursuit of carbohydrates. Where to get them, what’s the best kind, are they complex or simple, etc. And I felt kind of sad when my friends, the carbohydrates, started taking some serious media heat for being “bad for you” (thank you Robert Atkins for THAT). However, protein has always been the shining star of the macro world.

A complete ACL reconstruction and 2 foot surgeries later, I’ve had to supplement my endurance running with more and more weight lifting. The world of powerlifting is a fascinating sport filled with athletes of literally every age, weight and shape. But we all have one thing in common: building and maintaining muscle mass is our religion and protein is the foundation by which that religion is built. If you really think about it, however, we are all body builders in some respects, building our bodies to do what we want them to. The truth is that endurance athletes and bodybuilders have similar needs for protein, but the way in which the body uses the protein differs. Bodybuilders need protein primarily to increase muscle tissue; endurance athletes need protein primarily to repair existing muscle tissue that is undergoing constant breakdown from day–to–day training.

Greg van AVermaet

Endurance athletes need protein to repair muscle tissue that is constantly being broken down.

Protein is an essential nutrient which helps form the structural component of body tissues and is used within many biological processes. It is not a fuel source for the endurance athlete but rather is used to make enzymes, antibodies to help us fight infection as well as DNA the building blocks to life. Most protein is stored in the body as muscle so it makes sense that if you increase activity, perhaps to improve health and fitness or body composition, you also need to recognize protein as being essential and make sure you’re getting enough in your diet. But how much? And how much is too much?

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Endurance athletes tend to focus on carbohydrate intake and pay little, if any, attention to protein. As a result, protein deficiency appears often among endurance athletes, with its inevitable negative effects on performance and health. Serious endurance athletes do need considerable amounts of protein, far above the normal adult RDA, because maintenance, repair, and growth of lean muscle mass all depend on it, as well as optimum immune system function. Low dietary protein lengthens recovery time, causes muscle weakness, and suppresses the immune system. Chronic protein deficiency will cancel the beneficial effects of your workouts; instead, you will become susceptible to fatigue, lethargy, anemia, and possibly even more severe disorders. Athletes with over-training syndrome usually have protein deficiency.

The studies, recommendations and numbers vary. Pedersen, Kondrup and Brsheim (2013) conducted a systematic literature review of 5,718 abstracts and assessed the evidence as probable for an estimated average requirement of .66 grams protein per kg of body weight/per day.  This review also found that the relationship between high protein intake and cancer and cardiovascular diseases were inconclusive. Currently the ISSN (International Society of Sports Nutritionists) recommends 1.4 to 2.0 grams of protein per kilogram of body weight per day.

However, there is more research that suggests that an over-abundance of protein will not likely be harmful – provided you’re in good health and have no history of liver or kidney problems. Protein is broken down into amino acids in the gastrointestinal tract and subsequently absorbed into the bloodstream. Any extras that aren’t used for new protein synthesis are stripped of their amine groups, rearranged in the liver, and used for fuel. The unused nitrogen is readily excreted by the kidneys, so as long as you’re drinking plenty of fluids, the extra protein would not be harmful (Pedersen et al., 2013).

In short, there seems to be no magic sweet spot of protein intake that every athlete has to hit on the nose every day. More important that the amount of protein consumed is the timing of protein intake. Numerous studies have demonstrated that exercise-induced muscle damage is reduced when protein is consumed immediately before and during workouts and that muscle repair proceeds most rapidly when protein is consumed immediately after workouts.

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The two most common forms of protein preparations are whey concentrate and whey isolate. The main difference is that isolates are more pure than concentrates, meaning other non-protein components have been partially removed to “isolate” the whey protein. Many concentrates are 80% protein, while whey isolates are typically about 92% protein. Most whey concentrates and isolates are available as intact proteins, but either can be also hydrolyzed. Hydrolysates have been partially broken down by exposing the protein to heat, acid or enzymes that break apart the bonds linking amino acids. This makes it taste more bitter, but also allows it to absorb more rapidly than a concentrate or isolate.  

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Right after your ride, go to work helping your body rebuild.

Most of us endurance athletes know by now that the optimal window for protein intake after a workout is within about 30 minutes, 60 minutes worst case scenario. Experts suggest that the carb to protein ratio of this recovery snack be 4g carb to 1g protein or 3 to 1.  So remember to bring along a protein bar, shake, nuts or some other protein-rich snack that can be consumed almost immediately after your next sweat session.

Marcia holds a Master of Applied Exercise Science degree from Concordia University, Chicago.  She is also an ACE certified Health Coach as well as a Certified Sports Nutritionist through the International Society of Sports Nutrition.  As a marathon runnerX45, Hood-to-Coast captain, Ironman triathlete, Tough Mudder and Crossfit Masters competitor, Marcia knows first-hand the importance of proper nutrition in endurance sports.

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Caoillean H., M., Hector, A., & Phillips, S. (2015). Considerations for protein intake in managing weight loss in athletes. European Journal of Sport Science, 15(1), 21-29.

Masedu, PhD., F., Zirulo, S., Valenti, PhD., M., & Di Giulio, PhD., A. (2012). Resistance training and protein intake: Muscular mass and volume variations in amateur bodybuilders. International  SportMed Journal, 13(2), 58-68.
Moore, D. (2014).  Beyond muscle hypertrophy: why dietary protein is important for endurance athletes. Applied Physiology, Nutrition & Metabolism, 39(9), 987-999.

Pedersen, A., Kondrup, J., & Brsheim, E. (2013). Health effects of protein intake in healthy adults: A systematic literature review. Food & Nutrition Research, 57, 1-30.

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