Group Fitness Instructor

Answer: B - Muscle fatigue is caused by a depletion of the body’s glycogen reserves, as exercise lasting more than 2 hours will tap the body’s glycogen reserves in order to maintain performance. When this occurs, the body uses fat and the glucose stored in the liver to supply energy to the muscles. As Runner’s World puts it “it's actually a bodily form of sedition. In some form or another, it becomes a collapse of the entire system: body and form, brains and soul.”