The hormone cortisol is synthesized in the adrenal cortex. Frequently called a stress hormone because it’s released rapidly into the blood during any type of acute stress, cortisol is nevertheless essential to life. It also has a dark side: It’s the most catabolic hormone in the body and is the most potent hormonal stimulus to muscle breakdown. In fact, anabolic steroid drugs build muscle in significant part through their cortisol-opposing properties.
Studies show that in younger men the body adjusts to continued exercise by blunting cortisol release. Since the body is in a constant battle between catabolic and anabolic reactions, anything that controls excess cortisol release during exercise should tip the metabolic balance in favor of anabolic hormones, such as testosterone and growth hormone, thus favoring muscular gains.
Age blunts the cortisol-adjusting feature of exercise. Because older men produce higher levels of cortisol when they train, it’s harder for them to make muscular gains.
A recent study suggests a solution to this age-related cortisol problem.1 Five older men, average age 62, trained using a nine-exercise-station protocol on two different occasions. During one session they drank a placebo, and during the other they downed a drink containing carbohydrates. With the carb drink the men showed higher blood glucose levels, but, more important, their levels of cortisol release during exercise were significantly blunted.
One problem with drinking carbs during training is that they completely blunt fat release, though that’s a moot point during weight training because bodybuilding workouts are typically anaerobic, relying on stored muscle glycogen and blood glucose instead of stored fat as major energy sources. Considering that blunting cortisol may remove the brakes on muscle gains in older men, it may be more prudent for that age group to drink some carbs during the workout. Such drinks should never contain more than 7 percent carbs, though. Any more may lead to inhibition of fluid uptake and possible nausea during the workout—which, ironically, may lead to a rise in cortisol.
1 Tarpenning, K.M., et al. (2003). CHO-induced blunting of cortisol response to weightlifting exercise in resistance-trained older men. Eur J Sports Sci. 3(2).
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