Muscle glycogen is the primary fuel powering anaerobic exercise, such as weight training, and it’s partially depleted during exercise. To promote muscle recovery and repair following exercise, it’s vital to restore depleted muscle glycogen levels. There are various ways of doing that, including the intake of carbohydrates, especially simple, or high-glycemic-index carbs, following a workout. Since glycogen is nothing more than a complex, branched-chain form of carbohydrate, it makes sense to get your carbs after a workout to replenish muscle glycogen. Simple carbs promote a greater release of insulin, which, in turn, activates the primary enzyme required for muscle glycogen synthesis, glycogen synthase.Research shows that adding protein to postworkout carbs works even better than carbs alone because amino acids in protein boost insulin release. Some studies show that the added calories, not the protein, do that, but scientists hotly debate that.
Single amino acids have also been identified as promoting the glycogen-repletion process. Arginine may help make glucose available for muscle glycogen synthesis, but other studies dispute that. Glutamine may help replenish glycogen because of its role in gluconeogenesis, the process of converting noncarbohydrate sources, such as amino acids, into glucose in the liver.
Fenugreek seeds contain high levels of 4-hydroxyisoleucine, an amino acid not found in animal proteins. It mimics the effects of insulin in a high-carb environment. Specifically, 4-HL directly stimulates activity in the beta cells of the pancreas, the site of insulin synthesis and release. A recent study examined the effects of combining a high-carb intake and 4-HL on muscle glycogen replenishment.1
Trained cyclists who’d fasted overnight did a 90-minute glycogen-depleting ride on exercise cycles. They then got either high-dose glucose alone or glucose combined with 4-HL. The combination of high-dose glucose (1.8 grams per kilogram of bodyweight) and 4-HL (two milligrams per kilogram of bodyweight) led to 63 percent greater muscle-glycogen replenishment than glucose alone did. There was no change in circulating levels of insulin, which pointed to an independent effect of the 4-HL alone.
The implication is that using some type of 4-HL supplement would greatly accelerate muscle glycogen synthesis, and since it doesn’t affect insulin levels, there’s less chance of carb spillover into bodyfat synthesis. In any case, however, nearly all carbs you take in following a workout go directly into muscle and liver glycogen synthesis; energy sources are the body’s primary concern.
1 Ruby, R.C., et al. (2005). The addition of fenugreek extract to glucose feeding increases muscle glycogen resynthesis after exercise. Amino Acids. 28:71-76.
©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
