Supplement Savvy - 6/22/05.

Last week I reviewed a number of studies presented at this year's American College of Sports Medicine Meeting. This week I'm focusing on a series of studies presented in "Protein Metabolism" session.

Short-term Carbohydrate Restriction Increases Both Proteolysis & Protein Synthesis

Carbohydrate restrictive diets are all the rage. Although their mainstream popularity is waning, carbohydrate restriction is still a regular practice among bodybuilders and general strength trained athletes, alike.

	A Short History Of The Low-Carbohydrate Diet. But believe it or not he low carb diet didn't start with Dr. Atkins or with Dr. Di Pasquale's Anabolic or Metabolic Diets. It actually started with a London undertaker more than 140 years ago. [ Learn More ]

Therefore, the purpose of this study was to assess the effects of a carbohydrate restricted diet on whole body proteolysis (protein breakdown) and skeletal protein synthesis (building).

Four men and four women participated in this small, pilot trial. They were first fed a "standard diet" for two days (60% carbs, 30% fat, and 10% protein) followed by a carbohydrate restricted (5% carbs, 60% fat, 35% protein) diet for seven days. Assessments were conducted on day two and seven of the carbohydrate restricted diet phase.

Upon completion of this short study, it was found that both whole body protein breakdown and skeletal muscle synthetic rate were increased (basically, breakdown increased, but so did synthesis).

There were no subsequent changes in fat free muscle mass, suggesting that the breakdown was offset by synthesis.

Take home message: The amount of dietary carbohydrate effects protein metabolism. It is important to maintain adequate carbohydrate intake and also an adequate protein intake; the goal of this approach is to minimize whole body proteolysis and maximize protein synthesis.

Recovery Of Endurance Running Capacity Following Ingestion Of Carbohydrate Plus Protein

Recovery nutrition has been discussed ad nausea. However, many still don't understand its importance in the whole realm of training and nutrition. Similarly, others are still confused as to what should comprise a recovery meal. As you may be aware, carbohydrates are necessary for glycogen (storage form of carbohydrate) resynthesis.

	Recovery Nutrition! The goal of recovery nutrition is to prepare the body for the next workout. While the body is at rest, it is the athlete's job to refuel it. By refueling the body, athletes may reduce muscle soreness and cramping, common complaints for many athletes. [ Click here to learn more. ]

Similarly, protein is crucial post-workout to help maintain a positive nitrogen balance. And the combination of the two has elicited a great insulin response than either alone. A greater insulin response means more rapid uptake of carbohydrate by the muscles and, subsequently, faster glycogen resynthesis. Therefore, a good amount of research has been conducted to measure the effects of both in a recovery beverage (or meal).

The purpose of this study was to determine whether the addition of protein to a carbohydrate beverage enhances recovery from endurance exercise.

Six active males participated in three separate trials. Each trial involved a run to purposefully deplete glycogen stores (90 minutes and 70% of VO2max). During the 4 hour recovery, subjects ingested solutions every 30 minutes. These contained either 0.8 g CHO/kg/hr + 0.3 g/kg/hr (CHO-Pro trial), 0.8 g CHO/kg/hr (CHO only), or a solution of 1.1 g CHO/kg/hr (CHO-CHO trial). The CHO only solution matched the CHO-Pro for CHO content; the CHO-CHO trial matched the CHO-Pro for energy content.

Results: The results demonstrated that endurance capacity was greater following both the CHO-PRO and the CHO-CHO only groups compared to the CHO alone group. Similarly, significantly greater insulin responses were seen with the CHO-PRO and CHO-CHO groups vs. the CHO. The CHO improved running time to exhaustion (not surprising because of its importance in glycogen resynthesis).

There was no difference between the CHO-Pro and CHO-CHO groups, however with regards to run time to exhaustion. What this group of researchers did not study, though, was nitrogen balance; the additional protein could have helped maintain a positive nitrogen balance. Since there was no difference between groups with regards to run time to exhaustion, they were both effective in that regard; maybe the additional protein would provide its own benefit, though. There is surely loads of research to support that theory.

The Combined Ingestion Of Protein & Free Leucine With Carbohydrate Increases Post-Exercise Muscle Protein Synthesis

Resistance training is necessary for hypertrophy - we know that. Resistance training also stimulates both protein synthesis and degradation; seems to be a bit of a paradox, doesn't it? This is why it is crucial to feed the body what it needs post-workout; recovery food intake is crucial for net protein balance to become positive.

Some research has suggested that not only are protein and carbohydrate beneficial, but added leucine helps optimize the required protein synthesis. The reason for this is it appears to have a very high insulinotropic potential (fancy way to say it increases insulin levels).

This study was therefore conducted to determine if additional leucine had an added benefit above and beyond that of carbs alone and carbs with protein. Eight male subjects were assigned to either CHO only, CHO plus protein, or CHO plus protein plus leucine following 45 minutes of resistance exercise.

Results: The results demonstrated the CHO+protein+leucine. In addition, the added leucine resulted in a significantly greater whole body net protein synthesis. These results demonstrate the carb+protein+leucine effectively stimulates muscle protein synthesis compared to carb only. A high quality whey protein will also provide a fairly significant dose of free leucine, so try a carb+whey protein product.

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Conclusion

So from these studies, we reiterate the importance of protein in a post-workout product. There are a number of products available here at Bodybuilding.com; you can even go to your local grocery store for some good 'ol low-fat, chocolate milk. The key with a post-workout product (and all of these studies and many others support this) is you want a 3 or 4:1 carbohydrate to protein ratio.

What that means is that for every 3 or 4 grams of carbohydrate, there should be 1 gram of protein. For example, if you were to consume 1 cup of chocolate milk, you would get approximately 30 grams of carbs and 10 grams of protein (3:1). Also remember that it is important to consume this post-workout product as quickly after a workout as possible; this is of utmost importance if you plan to train again later in the day, because it will help facilitate rapid glycogen storage.

It is not as crucial if you don't plan to train until the next day (glycogen takes approximately 24 hours to be fully restored). However, it is most important for not allowing your body to maintain a positive nitrogen balance. Remember, resistance training increases protein synthesis and protein degradation; it is crucial to keep the latter one to a minimum and that can be done by consuming sufficient levels of protein, immediately after a workout and of course throughout the day.