The picture on the front cover of this book depicts a young man pulling a fishnet, a task of practical relevance for many centuries. It is a complex task, involving load transmission throughout the body, intricate balance, and eye head-hand coordination. The quest toward understanding how we perform such tasks with skill and grace, often in the presence of unpredictable pertur bations, has a long history. However, despite a history of magnificent sculptures and drawings of the human body which vividly depict muscle ac tivity and interaction, until more recent times our state of knowledge of...