As anyone who takes up a new sport quickly discovers, even basic athletic moves require high levels of coordination and control. Whether dribbling a basketball or hitting a backhand, limbs must be synchronized and bodies balanced, all with precise timing. But no matter how diligently we watch the pros or practice ourselves, the body’s inner workings remain invisible. The Hidden Mechanics of Exercise reveals the microworld of the human body in motion, from the motor proteins that produce force, to the signaling molecules that activate muscles, to the enzymes that extract energy from nutrients. Christopher Gillen describes how biomolecules such as myosin, collagen, hemoglobin, and creatine kinase power our athletic movements. During exercise, these molecules dynamically morph into different shapes, causing muscles, tendons, blood, and other tissues to perform their vital functions. Gillen explores a wide array of topics, from how genetic testing may soon help athletes train more effectively, to how physiological differences between women and men influence nutrition. The Hidden Mechanics of Exercise tackles questions athletes routinely ask. What should we ingest before and during a race? How does a hard workout trigger changes in our muscles? Why does exercise make us feel good? Athletes need not become biologists to race in a triathlon or carve turns on a snowboard. But Gillen, who has run ten ultramarathons, points out that athletes wishing to improve their performance will profit from a deeper understanding of the body’s molecular mechanisms.