One of the most common temptations when gains begin to slow or even stop is to increase the training load. The first thought that comes to mind is, “Maybe I’m not doing enough.” So we add another exercise, then another set—the more desperate might even add more workouts. Urban legends about Arnold and the like busting plateaus by squatting for hours on end don’t help the matter. Add to this the gym culture that reveres long and hard workouts that supposedly test your mettle, and all of this can lead to overtraining.
Most overtraining research focuses on endocrine symptoms such as elevated catecholamines and cortisol levels, and also metabolic and nervous system problems that lead to poor insulin sensitivity, sleep difficulties, and reduced appetite. But could there be more direct negative effects from overtraining that are important to bodybuilders?
A recent study published in the International Journal of Sports Medicine shows that overtraining may in some instances directly prevent muscle growth by elevating levels of myostatin within the muscle. Myostatin is classified as a negative regulator of muscle tissue; it inhibits muscle stem cell proliferation and differentiation, and attenuates adult muscle fiber protein accretion, resulting in decreased skeletal muscle mass.