Book excerpt: How much of a person’s body weight is made up of muscle? Can you learn to control your heart rate using your mind? How does taking steroids affect muscles—and why are steroids dangerous? What causes hiccups? The answers to these puzzling questions—and 97 more—are revealed in this thought-provoking book about muscles. From basic information on how muscles work to more complex issues such as how diseases and injuries affect muscles, science expert Faith Hickman Brynie provides authoritative information about the human muscular system.