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By Patricia B. Rosen, MD, MPH

Amino-Acids.svgWhy is it important to consider protein when involved in endurance events? 

I think we have all considered the fact that just plain glucose doesn’t quite make it.  The research shows that adding protein to your fuel during the race significantly increases the time to exhaustion and reduces post exercise muscle damage.

The ingestion of proteins may also help maintain glycogen stores.  However ingesting a hamburger or chili during an ironman just doesn’t work that well.  I mention this as I understand that one of the first ironman racers (John Collins) did use chili as fuel on the bike, and chased it with a beer on the run!  He did finish which is amazing!

So the question is how do we achieve the benefit of proteins without the adverse gastrointestinal affects?

We need to look at the basics, what are amino acids and proteins?

Amino acids are the building blocks of proteins and muscle tissue. Many physiological processes relating to activity, energy, recovery, muscle strength gains and fat loss, as well as mood and brain function, are linked to and require amino acids.  The 23 or so amino acids are the molecular building blocks of proteins. Nine are termed essential amino acids, meaning that they must be supplied from some food or a supplement; the others, which used to be classified simply as nonessential, can be synthesized by the body

An important variable is the ability of the body to synthesize non-essential amino acids when they are metabolized or depleted during exercise.  In particular glutamine, which is used during prolonged exercise or stress may need to be replaced if reduced by over training or severe stress of any sort.  Even though it is the most abundant amino acid in the body it is difficult to keep up with demand under severe stress.  When plasma amino acid concentrations are depleted which is the case in hard training athletes, the immune system also becomes suppressed making the athlete more susceptible to sickness.  Although glutamine has been shown to increase in after short term high intensity exercise, long term exercise is related to a decrease in glutamine.  This decrease has been associated with the development of illness following long term exercise (marathon and longer) and with overtraining syndrome.  The athlete feels fatigue, has sleep disturbances and difficulty performing much less functioning.  Heart rate responses are not consistent with effort and the resting heart rate is elevated.  Development in particular or respiratory illnesses is common. Supplementation with branched chain amino acids helps to prevent this decrease and the consequences of overtraining.

Branched chain amino acids include Leucine, Isoleucine and Valine.  These are simply amino acids that have a branched structure.  Studies have shown that the use of an effective dose of BCAA’s while endurance training helps to increase levels of lean muscle mass and to prevent overtraining syndrome.

Of interest the major symptoms of overtraining may be affected by an alteration in the ratio of amino acids. The amino acid tryptophan, the precursor for serotonin, may be increased in the overtraining syndrome resulting in an imbalance with branched chain amino acids (BCAA’s).  This may result in a feeling of fatigue and depression.  This physiological alteration is known as central fatigue.  Supplementation with BCAA’s prevents this increase in serotonin and central fatigue.

The content and balance of amino acids, and the ratio of essential to non-essential, helps determine the value of protein quality.  However the ability to use these amino acids requires that they be digestible, absorbable and bioavailable.  That means the amino acids must be delivered to the tissues when needed.

Eating quality food is the best way to get amino acids into the diet, through lean meats, and dairy products and vegetables and legumes. However, unlike John Collins during that first Ironman, most athletes do not want to eat a bowl of chili on the bike.  When you eat foods, high quality or not, amino acids are digested and metabolized by the liver.  Thus much of the protein is not used as it exceeds the ability of the liver to use it.  Eating regular food during and right after an intense effort just isn’t practical even if the basic components for muscle healing are there.

Note also that naturally occurring food proteins contain only 4% to 8% of their amino acid as glutamine. It is also easily destroyed by cooking. Raw vegetables can be a good source of glutamine though dietary glutamine is not easily absorbed through the intestine.

Bioavailability is important from the point of view that you want to get the nutrition into your system as soon as possible and that you don’t want gastric upset of any sort.  Its been discussed that complete proteins simply do not deliver the amino acids quickly or completely enough as the free form amino acids.  Complete proteins can also be hard to digest when exercising whereas many athletes experience gastric distress when doing so.  You can imagine that eating chili or perhaps some steak is not going to be a good idea when your stomach is bouncing around for 140 miles.  The value of free-form amino acids is that they don’t require digestion.   Having them available in a drink is more palatable and practical.

The best way to deliver amino acids is to administer them in a powdered form for oral use.  Unbound or free form amino acids can access the general circulation within 15 minutes.  Thus the use of branched chain amino acids during training helps to fight fatigue and helps muscles to recover after a strong effort.

A recent study shows that ingestion of a protein hydrolysate (a pre-digested protein) as opposed to its fully intact protein accelerates not only protein digestion and absorption for the gut but also augments postprandial amino acid availability and increase incorporation of dietary amino acids into skeletal muscle.  This study confirms that complete proteins simply do not break down into their amino acids fully and at the rate of hydrolyzed protein or free form amino acids.  The body can not manufacture its own BCAA’s so this must be supplied through diet and supplementation.  Added benefits are improved exercise tolerance and better performance in the heat.

A new hypothesis states that the addition of protein during exercise could provide precursors for Krebs cycle intermediates. These intermediates decrease during exercise and decrease energy production.  Although carbohydrate supplementation is thought to assist this process, it may not be as efficient without amino acid supplementation.

So I think the choice is simple. I like chili as much as the next person, but really, it gets kind of messy while you’re in your aerobars.  The research clearly supports the use of BCAA’s and free form amino acids.  I like the EFS sport drink and the shots for the bike and the run.  I use Ultragen during the last half hour on the bike and for recovery.

EFS electrolyte drink is fortified with 2,000 mg of amino acids per serving.  This is in the most bioavailable from of amino acids available. These amino acids include AjiPure amino acids. After about five minutes, 100% of this form of amino acids are released compared to 46% from other amino acids.

Ultragen, a recovery drink, has whey protein isolate and whey protein hydrolysate which are absorbed rapidly.   Ultragen is also fortified with 6g of glutamine and 4.5g of branched chain amino acids.  Following a race these proteins are delivered at the critical first 30 minutes when the muscles are most open to absorbing nutrients and a protein that can be absorbed during recovery and rebuilding.

Practically speaking the way to get your protein and improve endurance is to use free form amino acids early in the race and through out the race and at the end for recovery to enhance performance at the next race.  I would recommend looking at the blogs on the First Endurance

web site to see how some of the pros stay well and do well using this science.

Ciao!  See ya’ at the chili parlor!  After the race!

Patricia B. Rosen, MD, MPH

Patricia Rosen has qualified and is racing the 2010 Ironman Kona


Ivy, J: Res Pt, Sprague RC, Widzer MO

Effect of a carbohydrate-protein supplement on endurance performance during exercise of varying intensity.

International journal of sport nutrition and exercise metabolism, 2003; 13; 388-401

MJ Saunders, MD Kane, MK Todd

Effects of a carbohydrate-protein beverage on cycling endurance and muscle damage

Medicine and Science in Sports and Exercise, 2004; 36: 1233-1238

M Parry-Billings, R, Budgettt, Y Koutedakis, E Blomstrand, S Brooks, C Williams, PC Calder, S Pilling, R Bainrie, EA Newsholme

Plasma amino acid concentrations in the overtraining syndrome:  Possible effects on the immune system

Medicine and Science in Sports and Exercise:  1992; 24: 1353-1358

Armstrong, L., VanHeest, J.

The unknown mechanism of the overtraining syndrome: clues from depression and psychoneuroimmunology. Sports Medicine, 2002; 32: 185-209.

R Koopman, N Crombach, A P Gisen, S Walrand, J Fauguant, A K Kies, S Leomsquet, WHM Saris, Y Boirie, LJC van Loon

Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein.

American Journal of Clinical Nutrition, 2009; 90:06-115