Many of us tend to take our muscles for granted. They are the unsung heroes of our bodies. They are the stuff that moves us and keeps us healthy. But as we age, how much can we rely on our muscles? What are the secrets of our muscles? Journalist and author Bonnie Tsui takes a deep dive into the science, history, and personal narratives that shape our understanding of muscle in her book, On Muscle: The Stuff that Moves Us and Why it Matters.