Strength Training, Amino Acids and Insulin: A Love Story

Woman Curling Bicep

Strength training fans are constantly looking for new ways to build muscle mass using a combination of exercise and nutritional strategies. Studies consistently show that helping your body produce essential amino acids aids in strength training success.

Amino Acids Build Muscle Mass

In short, amino acids are the chemical units of the body that comprise proteins. Proteins are essential for muscle production, and worth understanding for anyone serious about strength training. Take the study conducted by Biolo, et al, in 1997. He and his team found that infusing amino acids (40 g) after resistance exercise drastically increased net muscle protein balance and muscle protein synthesis (see Biolo et al, 1997). What’s more, the anabolic effect of the amino acids following exercise was greater than at rest, indicating an additive effect.

Of course, intravenous infusion isn't a practical manner of delivering amino acids—and the study didn’t address whether the ingestion of amino acids is as effective as infusion as a means of stimulating muscle protein synthesis.

Enter Tipton. Tipton, et al, examined the effect of orally administered amino acids (one liter solution with 40 g of amino acids) following resistance exercise on muscle protein synthesis. Interestingly, the researchers found that total muscle protein synthesis from amino acid ingestion was comparable with amino acid infusion (see Tipton et al, 1999). Since amino acid availability can be raised as efficiently with oral ingestion as with infusion, consuming a source of amino acids following resistance exercise (such as a nutritional supplement or food) should encourage muscle anabolism.

Insulin Reduces Protein Breakdown

In addition to the studies by Tipton and Biolo, other researchers have found that protein production is enhanced by insulin. Increased insulin levels related to carbohydrate ingestion may reduce the muscle protein breakdown that usually happens following resistance exercise. Since amino acids increase muscle protein synthesis—and insulin hinders muscle protein breakdown—the blend of amino acids and carbohydrates (to provoke insulin secretion) may be a strong anabolic (i.e. muscle-building) mixture.

So, what’s the upshot? Well, Rasmussen, et al, analyzed the effects of ingesting a beverage containing 6 g of essential amino acids and 35 g of carbohydrates (sucrose) on actual muscle protein metabolism following resistance exercise (see Rasmussen et al, 2000). Not only did this carb-amino acid cocktail raise insulin and amino acid levels, but it also altered the net muscle protein balance from negative to positive. Muscle protein synthesis was excited in muscle protein breakdown without the anticipated (and related) rise of muscle protein breakdown. The anabolic reaction was the same whether the beverage was consumed 1 hour or 3 hours following resistance exercise.

For more effective strength training, here’s the bottom line: For maximum protein-producing results, an amino acid- and carb-rich nutritional supplement following your workout is proven to help you succeed.

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