Post Workout Nutrition – Chocolate Milk!

From Running Research News, Volume 18, Issue 7, September 2002

Research conducted by Mark Tarnopolsky, among others, has shown that the timing of a high carbohydrate diet can greatly enhance muscle glycogen levels.  Eating a high carbohydrate meal within 30 minutes of either endurance or resistance exercise appears to improve total daily muscle glycogen re-synthesis.  Additionally, this routine also positively effects protein metabolism. 

One to two grams of carbohydrates per kilogram of body weight within 20 to 30 minutes after exercise.  In addition you should be consuming 10 to 20 grams of protein.  It’s suggested that natural foods, not special drinks, be used because we assimilate amino acids better when they come from balanced proteins in real food.

And the ideal post workout food?  Chocolate Milk!

Eating carbohydrates immediately after endurance or resistance workouts improves re-synthesis of glycogen.  This also improves protein metabolism.

Proteins are made of amino acids.  Breaking down branched-chain amino acids is controlled by an enzyme – BCOAD.  A protein rich diet increased BCOAD activity.  But, the presence of carbohydrates reduces the activity of BCOAD.  Thus, proteins are not broken down.  Training also reduced the activity of BCOAD.  This is a good thing, since muscles are mostly protein, they will be broken down less and able to build with reduced BCOAD activity.

High volume training will deplete muscle glycogen and can lead to a “negative nitrogen balance,” because we are losing more protein than we can build.  This is especially a problem for women, who tend to have low protein and calories intake. 

Mark Tarnopolsky of McMaster University, Hamilton, Ontario performed a study on post exercise diets.  Their overall diet was 58% carbohydrates, 16% protein and 26% fat calories.  The post exercise beverage (Results from Mead-Johnson, Canada) was 66% carbohydrate, 23% protein and 11% fat calories.  The post exercise beverage was taken immediately after exercise, instead of prior to exercise.

The Results were that more fat was used during exercise (a good thing).  More importantly, when Results was taken after exercise, Nitrogen Balance was positive (a very good thing – protein stores were increased).  Weight loss was also reduced.  Most importantly, when Results was taken after exercise, the athletes were able to exercise 47% longer at the end of the test!  The only difference was the timing of the intake of Results – before or after exercise.

In addition, eating carbohydrates after exercise increases insulin in the blood.  Studies have shown that this results in a positive protein balance.  Muscles lost 30% less protein post exercise after eating carbohydrates.  Muscles were able to build-up in response to the training.  Muscles took up three times the amount of Alanine ( a specific amino acid).

The bonus is that you will have a better training session on the following day!  Remember, muscles are most receptive to talking up carbohydrates in the 2 hours immediately following exercise.  But, the rate of up-take diminishes after 30 minutes.

Tarnopolsky recommends eating a minimum of 1 gram of carbohydrates per kilogram of weight (2 grams are better) within 20 minutes, and 10 to 20 grams of protein are suggested.

Skim chocolate milk is the best source of the carbohydrates and protein:

Two cups of skim chocolate milk, 1 cup of an electrolyte/energy drink, one banana and a bagel.  This will provide:

Whey protein from milk is rapidly absorbed, while the casein protein from milk is absorbed more slowly. 

This post exercise meal is particularly important if you are doing two a day workouts.  Normally, it takes 24 hours to absorb carbohydrates.  So, it’s critical to get that carbohydrate boost.

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