Peak Performance: Elevate Your Game, Avoid Burnout, and Thrive with the New Science of Success

by Brad Stulberg

As you learned in Chapter 2, when we stress our bodies, they enter into something called a “catabolic” state. Our muscles, and even our bones, break down on a micro scale. The hormone cortisol is released, telling our body, “Help! We can’t handle this stress.” We become tired and sore, which is the body’s natural way of informing us it’s time to take a rest. If we neglect rest and keep pushing, the breakdown continues and, eventually, our health and performance suffer. But if we listen and allow the body to rest, it shifts from a catabolic state to an anabolic one, in which the body repairs and rebuilds so that it can come back stronger. This is to say that the stress of hard physical training breaks us down, and it is only when we follow stress with rest that adaptation and growth occurs. This is especially true with sleeping, which is a catalyst for physical growth. Just as the brain is actively processing the work we’ve done throughout the day, when we sleep the body is doing the same.