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Protein and Carbs: Best Postworkout Mix?

The notion that you must get a certain ratio of protein to carbohydrate following a workout is so widely accepted that it appears to be set in stone. Well, just as the mightiest stone edifices eventually fall prey to time and crumble, so does some nutritional dogma. Even so, to call the practice of taking protein and carbs after a workout a fad is an overstatement. The concept was developed over a number of years, based on sound scientific reasoning. For example, no one would argue against getting protein after a workout. Protein is required for muscle protein synthesis, which in turn leads to muscle hypertrophy if preceded by intense exercise stimulus. In recent years multiple prescriptions have been offered as to the best type of protein, the exact quantity and precisely when is the best time to take it. The focus on protein eventually narrowed down to amino acids, specifically essential amino acids.

Essential amino acids are the ones that cannot be synthesized in the body from other nutrients and must be supplied by food. While many bodybuilders continue to take in massive amounts of protein after a workout in the belief that it will prod gains in muscle size and strength, research finds that as few as six to 10 grams of essential amino acids are all you need postworkout to maximize muscle gains. Taking in more protein than you need just leads to increased oxidation of the excess protein in the liver. So if grams of essential amino acids are all you need for muscle gains to kick in, why do so many commercial muscle-gain sports supplements provide as much as 50 grams or more protein per serving?

One-word answer: marketing. Bodybuilders are so indoctrinated to believe that massive amounts of protein are required for building muscle that a supplement providing a mere 10 grams of essential amino acids would likely not prove to be a big seller. Hey, just a single large egg contains seven grams of protein, with a good supply of essential amino acids to boot. Some marketers, though, need to justify the often lofty price tags on specialized sports supplements. Such companies follow a kitchen-sink philosophy, providing not just megadoses of protein but also in some cases carbohydrate and other substances that may not be of scientific benefit other than looking impressive on a label that features “proprietary” ingredients. The trend may be changing, however. At least one company that I know of is selling an amino-based supplement that it claims is far more effective than any type of whey protein, the current gold standard in protein supplements. I have little doubt that these extravagant claims are based on recent findings that small amounts of essential amino acids are the way to go for muscle gains.

While protein has been recommended as the mainstay of a postworkout nutrition plan for years, dating back to the 1950s, the idea of combining carbs with protein is more recent—and not just any carb will do. For best results the advice is to use a high-glycemic-index, or rapidly absorbed, carb, along with a rapidly digested protein, such as whey. That combination is said to be ideal for encouraging increased muscle protein synthesis and decreased muscle breakdown. One of the key elements in the combo is insulin. While many amino acids themselves can provoke an insulin release, carbs, especially simple, high-glycemic-index carbs, are thought to be the most potent insulin-related nutrients.

Insulin, which is secreted by the beta cells of the pancreas, promotes the increased storage of carbohydrate as glycogen in muscles and liver and also helps the body store excess calories as fat. Older texts talk about how insulin pushes amino acids into muscle, which would increase muscle protein production. We now know that insulin is actually more permissive, in that it may lower muscle protein breakdown—an anticatabolic effect—but does not necessarily boost protein synthesis. Some studies dispute that and suggest that insulin can indeed spark protein synthesis if there are sufficient aminos in the mix.

It’s not difficult to see how this ties in with the protein-and-carb post-training combo. As noted, amino acids and whole protein sources, such as whey, rapidly provide amino acids for use in muscle-protein-synthesis reactions following training. Adding simple carbs would maximize insulin release, particularly in the presence of essential amino acids. The net effect should be considerably more efficient muscle protein synthesis after training, which means more muscle gains. Study after study confirmed those effects.

Nevertheless, the notion that protein should always be combined with carbs after training has come into question lately. Some studies show that just eating protein after a workout gives you all you need for muscle protein synthesis and that carbs are superfluous. To examine those effects, a new study looked at what happens when you take either protein alone or protein plus carbs after a workout.1

Nine men, average age 23, did two workouts consisting of one-legged extensions, four sets of eight to 12 reps to failure. Afterward they took either 25 grams of whey isolate protein alone or 25 grams of whey along with 50 grams of maltodextrin, a carb source. The drinks also contained amino acid tracers to determine the fate of the protein. It turned out that the whey protein alone was sufficient to maximize muscle protein production after training. The add-on carb didn’t add to the effect, although it did significantly elevate insulin more than the whey protein alone. Based on those findings, the authors suggest that you need only a low insulin response following training to maximize the increase in muscle protein synthesis; and getting sufficient protein will accomplish that. Surprisingly, the protein-and-carb comb was not superior at stopping muscle protein breakdown, despite the presence of high insulin and amino acids. The protein-induced insulin alone was enough for that purpose as well.

Keep in mind that this study used 23-year-olds as subjects. Other studies have identified insulin resistance in older people, who tend to lose a lot of muscle because the anticatabolic effect of insulin is blunted. If they get twice the amount of insulin that is secreted after a normal meal, they stop losing muscle and show increased anabolic effects, so I’d speculate that getting protein and carbs after a workout would be more efficient for those over 40. By the way, a high insulin release is known to boost nitric oxide activity, which would have the effect of widening blood vessels, increasing nutrient delivery to muscles.

Another aspect to consider—whatever your age—is complete muscle recovery after training. Even if we accept the idea that only protein is required for maximal protein synthesis after training, other considerations are involved. Carbohydrates are still the best nutrient for feeding glycogen synthesis after training. Glycogen is not only the major fuel source of muscles engaged in weight training but is also needed for full muscle repair and recovery. If you train a muscle that isn’t fully recovered from a prior workout, you risk overtraining and possibly injuring it. Indeed, a study published some time ago found that postworkout carbs are required for the full expression of insulinlike growth factor 1 in muscle. Localized IGF-1 differs from the systemic type secreted by the liver under the influence of growth hormone. It helps orchestrate both muscle repair and growth following training because it ups the activity of satellite cells, which are muscle stem cells needed for those purposes.

If you factor in the fact that any carbohydrate you take within two hours of a workout is used for glycogen replenishment and does not lead to fat synthesis, there is no reason not to grab some carbs after a workout. Though you don’t need them for muscle protein synthesis alone, for full recovery you’d be well advised to stick with protein-carb postworkout drinks.

—Jerry Brainum


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1 Staples, A., et al. (2010). Carbohydrate does not augment exercise-induced protein accretion versus protein alone. Med Sci Sports Exerc. In press.



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