The metabolic window is a term used in strength training to describe the 30-minute (give or take, dependent on the individual) period after exercise during which nutrition can shift the body from a catabolic state to an anabolic one. Specifically, it is during this period that the intake of protein and carbohydrates can aid in the increase of muscle mass.
Some theorists believe the metabolic window begins to close within minutes of the end of a workout. The same nutrients taken two hours later result in significantly reduced protein synthesis and muscle glycogen storage. Further research is needed into the effects of food and exercise timing, but methodology has to be considered in these experiments.