Fast Backward

Fifteen-year-old Bobby Hastings witnesses an atomic explosion near a top secret New Mexico army base in July of 1945. Terrified, he soon heads off on his bike for home, only to encounter something that rivals the blast for drama. A girl his age stands naked at the side of the lonely desert road: underweight, unwell, and speaking with a German accent. In the coming days, she unveils an impossible story about time travel and a heartbreaking outcome of the war. She begs people to believe her warning and prevent the awful future she claims to know too well. But even if they do believe her, and the story is true, the biggest question remains: can history be undone?

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 human movement was rather primitive. During the past century this has changed; we now have developed a considerable database regarding the com position and basic properties of muscle and nerve tissue and the basic causal relations between neural function and biomechanical movement. Over the last few decades we have also seen an increased appreciation of the impor tance of musculoskeletal biomechanics: the neuromotor system must control movement within a world governed by mechanical laws. We have now col lected quantitative data for a wealth of human movements. Our capacity to understand the data we collect has been enhanced by our continually evolving modeling capabilities and by the availability of computational power. What have we learned? This book is designed to help synthesize our current knowledge regarding the role of muscles in human movement. The study of human movement is not a mature discipline.