The Power of Protein in the Diet
of an Endurance Athlete

Protein, and its component amino acids are the building blocks of the body.  Proteins form the structure of cells, so protein is needed for both growth and repair of cells and muscle tissues. Proteins are involved in numerous essential biochemical functions necessary for life – for example, some proteins are enzymes that increase the rate of biochemical reactions and are vital to metabolism. Other proteins are important in cell signaling, and maintaining immune response.

Proteins are constantly being broken down into their component amino acids and reformulated back into proteins through a process known as protein turnover.  While most amino acids are recycled, via the body’s amino acid pool, a small proportion of this is consumed for energy and must be replaced on a daily basis.  More protein is broken down for energy if inadequate carbohydrate is consumed for any individual’s needs.  In feeding any athlete, a goal is to avoid unnecessary use of protein as a fuel, so that it can be “spared” for its primary purposes.

Different athletes have different requirements for protein:

Protein Requirements for a 65 kg Woman

Type	Grams protein/kg/ day	Grams protein/ day	Example:
			Food		Grams protein
Sedentary individual	0.8	52	1 whole egg 30 g (1oz) meat or cheese 250 ml milk 100 ml yogurt ½ chicken breast 4 servings of grains/starchy veg	7 7 8 4 18   8
Endurance athlete Add:	1.2-1.4   ®	78-91   ®	60 ml ( 1/4 c) whey powder +/- 90 g (3 oz) lean meat/fish/ 3 egg whites + 4 servings grains	+22 or + 21 + 8
Strength athlete Add	1.6-1.7 ®	104-110 ®	All under “Endurance athlete”	+50

Many athletes cross-train, or do sports that are a combination of both strength and endurance.   For Theresa, an appropriate amount of protein would be 1.2- 1.7 g/kg/day or about 80- 110 grams in total.  Taking too much protein can actually be a problem, because protein foods tend to be satiating, sometimes making it difficult to leave enough room for adequate carbohydrate calories!  During initial training, many endurance athletes eat too much protein and not enough carbohydrate!  It is unfortunate that many only learn what doesn’t work – the hard way, by literally being forced to stop before they reach their goal.

Muscle Protein Synthesis and Repair

Skeletal muscle tends to be broken down during exercise, especially during resistance exercise. If the amino acid pool in the body is well stocked, there is a net gain muscle mass following any work-out.  Recent research in nutrition has verified that muscle loss can be minimized during the workout and muscle gain can be maximized if there is adequate protein in the diet at all times. 

Regulation of Muscle Glycogen Repletion

The importance of maintaining muscle glycogen as a fuel source cannot be overstated, as it is the major fuel used by the muscles during prolonged exercise. After exercise, muscle glycogen is depleted and the body will not be able to store it again until adequate carbohydrate is made available. Ordinarily, when eating three or four balanced meals per day, glycogen synthesis is a relatively slow process, taking up to 48 hours to fully restock stores.  Do you recall the old rule “aerobics every other day; weight-training in between"?

We now have a better understanding.  Early intake of high GI carbohydrate immediately following exercise can make more frequent aerobic training possible. Early high GI carb intake is essential because it provides the most important substrate to the muscle.  It also takes advantage of increased membrane permeability of the muscle to glucose, as well as increased insulin sensitivity. Insulin is the hormone most responsible for drawing glucose out of the bloodstream and into the cells where the glucose is used or stored.  Supplementing immediately after exercise delays the decline in the body’s sensitivity to insulin.  With frequent supplementation a relatively rapid rate of glycogen storage can be maintained for up to 8 hours post exercise. If carbohydrate is taken alone, supplementation should occur frequently, such as every 30 minutes and provide 1.2-1.5 grams per kilogram body weight per hour.

However, the efficiency of muscle glycogen storage can be increased significantly with the addition of protein to a carbohydrate supplement.  If both carbohydrate and protein are consumed together, it is recommended that 0.8 grams carbohydrate per kilogram body weight plus 0.2 grams protein/k g body weight be consumed immediately and again 2 hours later, during a four-hour recovery period.  The addition of protein to a carbohydrate supplement also limits post-exercise muscle damage and promotes muscle building.  The best way to do this is to consume a post- workout shake or chocolate milk.  Follow with a good balanced meal about 2 hours later.

For example,  A 65 kg women would need 13 grams protein and 52 grams of carbohydrate.  The following basic recipe yields 22 grams protein and 45 grams of carbohydrate- almost perfect for the first supplement.  Fine as is or add 125 ml jjuice, milk or yogurt,  The second recoverywould be handled well by a small, balanced meal (Example: Sandwich with 1-2 oz meat/cheese/peanut butter +/- glass milk or an apple.)

Here is a basic recipe for a post workout shake:

1 ripe banana, peeled
50-100 ml  whey or soy powder (17-35 g protein)
250 ml frozen fruit (still frozen)
200-250 ml water, ice water, juice or other liquid

Place all ingredients in a large, 1- liter blender jar and blend until thick.  Mixture will expand to fill the jar. If not consumed all at once, cover the remainder and refrigerate until later in the day – or share with a friend. 
Tip:  buy large bunches of bananas.  Once ripe, peel and freeze in a baggie, then drop one into your blender still frozen

Will Theresa use any specialized amino acid containing supplements?

Many amino acids have been studied with respect to athletic performance, but to date most results are equivocal.  Energy drinks that may contain specific amino acids are often used inappropriately.  Before trying any sports supplement, it is wise to discuss this with an expert who knows your diet, your needs and your sport.  In the case of energy drinks, you need to ask yourself, “Do you really need the extra caffeine and sugar?” 

Because of her unique requirements as an ultra-endurance athlete, and based on her usual dietary habits, Theresa will experiment with be a limited amount of an energy drink that contains taurine, glucuronolactone, caffeine, B vitamins, sucrose, phenylalanine and glucose (aka “Red Bull”)

A review published in 2008 found no documented reports of negative health effects associated with the taurine used in the amounts found in most energy drinks, including Red Bull. Any commonly reported adverse effects are due to over-consumption of caffeine.  These include insomnia, nervousness, headache, and tachycardia. It is important to note that tolerance to caffeine is relatively low if someone does not routinely take caffeine-containing beverages. It takes less to get maximal impact.  The effects of caffeine tend to occur quickly (within 30 minutes) and take hours to subside.  To avoid interference with sleep, stop drinking caffeine- containing beverages early in the afternoon.

Baum and Weiss reported that Red Bull, as compared to a similar drink without taurine, favorably influence cardiac parameters, mainly an increased stroke volume, during recovery after exercise. Zhang and others reported that 7 days of taurine supplementation induced significant increases in VO2max and cycle ergometer exercise time to exhaustion; the ergogenic effects were attributed to taurine's antioxidant activity and protection of cellular properties.

References
Gibala, M.  Protein and amino acid supplements: do they work? Sport Sci Excange. 2002;15(4 Suppl):S1
Williams, Melvin. Dietary Supplements and Sports Performance: Amino Acids. J Int Soc Sports Nutr. 2005; 2(2): 63–67.

Clauson, KA, Shields KM  et al 2003. J Am Pharm Assoc Safety issues associated with commercially available energy drinks.

Baum M,  and Weiss, M 2001;20(1):75-82. The influence of a taurine containing drink on cardiac parameters before and after exercise measured by echocardiography.
Zhang M, Izumi I, Kagamimori S, Sokejima S, Yamagami T, Liu Z, Qi B.  Amino Acids. 2004 Mar;26(2):203-7. Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men.