The Power of Protein

May 01 2009

Protein needs of athletes have received considerable attention in recent years, and a growing amount of research is being dedicated to investigating the specific protein requirements of endurance athletes.  It can be confusing at the best of times to try to discern from the plethora of marketing information just how much protein is enough throughout the day, when you should have it, and what sources you should get it from.  Thankfully, research on the protein needs of endurance athletes is becoming increasingly clear, and the power of protein is being established.

A number of bodily functions and substances are dependent on the presence of protein in the diet, or, more specifically, the amino acids of which they are comprised.  Our bodies digest dietary proteins and break them down to their constituent amino acids, which are then shipped off to different parts of the body to be used in the synthesis and repair of muscle and connective tissue, supporting the nervous and immune system, creation of hormones, enzymes, nails, hair, and, in some cases, providing an energy source.


In all, there are 20 amino acids necessary in human nutrition, all of which are indispensable for maintaining health and fitness.  Amino acids are grouped into those our bodies have the ability to manufacture (non-essential amino acids) and those we must obtain through nutrition (essential amino acids).  A food source is considered a complete protein when it provides all of the essential amino acids. 


Animal protein sources like eggs, meat, fish and soybean products like tofu are examples of complete proteins.  Individually, vegetable protein sources only contain some amino acids, but must be combined in order to yield a complete protein (for example, combining a whole grain and legume). 


Eggs are considered the “perfect protein” as they contain all the essential amino acids along with wide array of other vitamins and nutrients.  The protein from an egg is the best absorbed and utilized natural source of protein and as such, eggs are assigned a biological value (BV) of 100.  All other protein sources are measured with respect to the egg.  Whey protein isolate has a slightly higher BV of 104, followed by milk proteins (BV=91), beef (BV=80) and soy protein sources (BV=71).  On a protein for dollars comparison, the egg is the hands down winner. 


For non-athletes, it is recommended that consuming 0.86g/kg body mass per day is sufficient for meeting the body’s requirements and preventing deficiencies.   Recommendations for endurance athletes however are in the range of 1.2-1.4g/kg body mass per day. For example, a 70kg endurance athlete requires 84-98g of protein throughout a typical training day.  Being on the low side of this recommendation equates to risking a loss of lean body mass, and this means decreased power and a resultant decrease in performance. 


As the amount of protein in the diet increases, so too should water intake.  The by-product of protein synthesis is ammonia, which needs to be converted to urea and excreted.  Too much protein will overwhelm this excretion system and can cause a build up of ammonia and a resultant increase in the acidity of the blood.  To compensate, the kidneys require more water to flush the urea from the system, and this can lead to dehydration and a decrease in performance.


Using protein during a race effort of short duration (<150min.) should be avoided, as our bodies don’t derive a significant supply of energy from the metabolism of protein.  We mainly depend on carbohydrates in the first 120-180 minutes of activity.  Including protein in any significant quantity in a pre-race meal or within an hour of training should also be discouraged, since it is slowly digested and will only serve to inhibit the absorption of carbs.

Since protein is not stored in the body for later use like glucose, it’s important to provide our bodies with protein throughout the day and after endurance workouts.  Recent research suggests that carbohydrate absorption is also increased by the presence of protein in recovery drinks and leads to increased glycogen synthesis.  In general, ingesting a recovery drink containing both carbohydrates and protein within 30 minutes of the end of a workout allows for optimal glycogen store replenishment, and allows the body access to the amino acid supplies it needs to repair any muscle or connective tissue breakdown that occurred during the training session.


Based on experience and experimentation, most athletes find a 3:1 carbohydrate to protein ratio works best for recovery.  Most athletes need to consume 0.5g carbohydrate per pound body weight after a workout.  Using these two figures, a 150 pound athlete would need 75g carbohydrate and 25g protein for optimal recovery. 


However, most athletes lack an appetite for solid foods immediately after a hard effort.  In this case, a good strategy is to use a liquid recovery drink immediately after a training session to start the recovery process.  Fruit smoothies that include a whey or soy protein supplement or a commercial recovery drink are great ways to begin replenishing your system after a workout.  It helps to have the ingredients for a smoothie ready to go prior to leaving for a long workout, insuring that it’s easy to initiate recovery as soon as possible even if you are tired following a sustained effort.


Within the next 60-90 minutes, follow the post workout recovery drink with a further recovery meal. Your digestive system will be able to handle so

Article by (Train Online)  |  May 01 2009

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