Protein during endurance events

This piece by Dr. Sal Tirrito speaks to the oft debated issue of using protein during endurance events. As many of us know, it’s often each to his/ her own on this one, as some people seem to respond better to protein during endurance events than others.

5 minute consult by Dr. Sal Tirrito

Is protein really needed in endurance events?

Although, carbohydrates and fatty acids are the primary fuel sources utilized during endurance events, more recently there has been a lot of data to support supplementation with protein during endurance events. In the past few years, clinical trials have clearly demonstrated that a protein/carbohydrate drink enhances performance when compared to a carbohydrate drink alone.

The reason for this is likely manifold and somewhat elusive. It is unlikely that the small amount of addition calories gained by drinking a carbohydrate/protein drink plays a significant role. It is more likely because during prolonged exercise, as glycogen levels become depleted, the body undergoes a process called gluconeogensis. Gluconeogenesis is a process that results in the generation of glucose from non-carbohydrate substrates such as pyruvate, lactate, glycerol, and amino acids. Gluconeogensis is an energy intensive process that can lead to accelerated muscle breakdown in order to liberate amino acids to drive the gluconeogenic process. Ingestion of small amounts of protein may help fuel the gluconeogenic process with enough protein to allow the body to avoid having to breakdown muscle.

However, having said this, this is still probably not the primary reason that a protein/carbohydrate drink enhances performance over a carbohydrate alone drink. Another, probably, more important reason is that a protein/carbohydrate drink appears to help stem cortisol release better than a carbohydrate only drink. Cortisol is a hormone (often referred to as “the stress hormone”) which is released in large quantities during intense exercise (a very stressful state to the body).

Normal cortisol release has widespread actions that help restore homeostasis (getting back to baseline functioning) after stress. In the normal situation, this is desirable, but for the endurance athlete it may have grave consequences. Although, cortisol increases circulating glucose concentrations (in the blood) which is desirable, it does this mainly by supplying amino acids for gluconeogensis by inhibiting collagen formation, decreasing amino acid uptake by muscle, and inhibiting protein synthesis. Also of importance to the endurance athlete is that cortisol also increases gastric acid secretion, potassium loss and is a potent diuretic. So by using a protein/carbohydrate drink to stem cortisol release, and by supplying a steady stream of protein (or ultimately amino acids) use may spare valuable muscle protein.

A last and more straightforward reason (one purposed by myself) has to do with recovery. It is widely accepted and practically endurance athlete dogma that protein/carbohydrates supplementation aides in recovery. The question I have often asked myself is, when does recovery start? The notion that recovery starts with the cessation of exercise is ludicrous and arbitrary. For the endurance athlete recovery happens before, during and after exercise. Recovery is an ongoing process that really has no starting or stopping point. Let’s face it, exercise is a highly catabolic process. It only makes sense that you want to start rebuilding muscle (or at least slow down muscle breakdown) the minute you start exercising.

As for the issue of how much protein, the answer is no one really knows but it is probably not very much (a few grams/hour). Protein is much harder to digest than carbohydrates (try eating a steak and than going for a run). So, if you have too much protein during an endurance event you risk some serious GI distress, too little and you may not get any benefit.

(Reprinted from Triathlete Magazine ‘ September 2008)

Salvatore J. Tirrito M.D., F.A.C.C.

HeartWise Fitness & Nutrition ‘President/CEO

Makers of XOOD Endurance Drinks

www.xoodhealth.com