The nutrient timing controversy by Jerry Brainum

 

 

A few years ago, a concept emerged known as nutrient timing. Simply put, the basis for nutrient timing was that by ingesting a combination of protein and carbohydrate within proximity of a workout, exercise recovery would be considerably enhanced. In addition, the provision of protein, usually in the form of a fast-acting source, such as whey, would provide a significant anabolic effect in muscle. Protein consumed alone, specifically essential amino acids, is enough to promote muscle protein synthesis, which is the underlying mechanism of muscle hypertrophy or growth. But researchers found that by adding carbs to protein, the release of insulin is enhanced above what normally would be promoted by consuming protein alone. Recent studies found that, for purposes of muscle protein synthesis alone, added carbohydrates (carbs) aren't required, since a rapidly-absorbed protein source, such as whey, is enough to elicit a significant release of insulin. On the other hand, there is more to promoting muscle gains than just enhancing muscle protein synthesis.

Muscle growth results from a combination of increased anabolic effects in muscle, coupled with a decreased breakdown of muscle. The latter effect is often called a catabolic effect. When anabolic effects, such as muscle protein synthesis exceed catabolic effects, the balance is tipped towards growth promotion. Shortly after you complete a workout, muscle protein reactions are upgraded, but so are muscle protein breakdown mechanisms. In fact, the breakdown phase is greater than the muscle protein synthesis phase, unless you take measures that will tip the anabolic/catabolic balance to predominately anabolic. This is where nutrient timing comes into play. By providing a rapidly absorbed protein source, such as whey, with a high glycemic index or rapidly absorbed carb source, you promote anabolism over catabolism. If all works out right, you get bigger and stronger.

Several published studies have confirmed that nutrient timing does work. In one study, bodybuilders were provided with a drink containing whey, carbs, and creatine. They consumed this drink either within proximity of a workout (such as before and right afterward) or ingested it several hours later. When ingested close to a workout, the bodybuilders gained twice as much muscle mass as when they consumed the same drink away from a workout. While this study provided the most dramatic example of how nutrient timing could foster muscle gains, other studies also confirmed the effect in various populations, such as both the young and the old. The first hint that ingesting nutrients such as protein and carbs immediately after exercise could provide benefits involved dogs trained on a treadmill.  The dogs were infused with a mixture of glucose and amino acids either immediately, or two hours after exercise. When the dogs were infused immediately, muscle protein synthesis significantly increased. But when the infusion was delayed for two hours, there was . . .