From the bestselling author of Why We Swim comes a mind-expanding exploration of muscle that will change the way you think about what moves us through the world. 'Remarkable ... A singular book about the true meanings of strength and flexibility, about our ability to define who we are and who we might be.' --Ed Yong, New York Times bestselling author of An Immense World and I Contain Multitudes In On Muscle, Bonnie Tsui brings her signature blend of science, culture, immersive reporting, and personal narrative to examine not just what muscles are but what they mean to us. Cardiac, smooth, skeletal--these three different types of muscle in our bodies make our hearts beat; push food through our intestines, blood through our vessels, babies out the uterus; attach to our bones and allow for motion. Tsui also traces how muscles have defined beauty--and how they have distorted it--through the ages, and how they play an essential role in our physical and mental health. Tsui introduces us to