Energetics of Human Activity provides a detailed, contemporary discussion of the efficiency of movement from a multidisciplinary perspective. The text explores the process by which humans optimize their energy expenditure in learning and controlling movements. As the first collaborative text that focuses on the energetics of motor coordination and control, Energetics of Human Activity is written by 24 international researchers in the movement sciences, including noted experts from the fields of psychology, physiology, and biomechanics. This presents the reader with a broad range of opinions and research findings. Collectively, the chapters discuss three topics of interest from a movement economy perspective: individual differences, motor learning, and the control of action. The hypothesis that minimization of metabolic energy expenditure is a universal constraint on the structure of emerging movement patterns is also presented by three movement subdiscipline perspectives. These approaches include the mechanics of human motion, the physiological cost of meeting task demands, and the effects of practice on performance. Each chapter provides a systematic basis for examining metabolic energy expenditure, presents the research findings that support the contention that energy expenditure regulates the development of movement patterns, and makes valuable suggestions to stimulate future research. The text also contains more than 100 figures that are clear and easy to interpret, making the information simple to understand. Energetics of Human Activity is a unique text that provides a complete perspective on metabolic energy expenditure from various disciplines. It is an invaluable resource for movement science professionals.

Abstract: Most humans use walking as the primary form of locomotion for short distances. However, many scientific questions remain regarding how and why we walk the way we do. This thesis explores the energetics of "nonlinear" (or curved path) locomotion both by using computer simulations and optimization techniques as well as human subject experiments. Specifically we (1) Measure the metabolic cost of human walking around circular paths at various speeds and radii, (2) explain the trends in the metabolic cost data qualitatively using 3d trajectory optimization of a simple biped model, (3) use metabolic cost data to explain the observation that people walk slower around tighter curves and faster while walking around straight lines or bigger curves, and (4) use metabolic cost data to derive optimal locomotor paths for human walking.

The description for this book, Muscles, Reflexes, and Locomotion, will be forthcoming.

The major determinant of walking's metabolic cost is the work required to redirect the centre of mass velocity during step-to-step transitions. My first aim was to isolate transitions from other contributors to walking mechanics. The results demonstrated that sagittal plane rocking reproduced the important characteristics of walking's transitions including a strong dependence of work on step length and a proportional increase in metabolic cost. My second aim was to use rocking to gain insight into pathological gait's elevated cost. Physics-based mathematical models predict sub-optimal transitions occur when one or both legs are unable to generate mechanical power with the optimal timing and magnitude, requiring a greater magnitude of total work and an increase in metabolic cost. I tested this prediction by immobilising the ankle joints of healthy subjects to simulate sub-optimal transitions and found that joint immobilization indeed caused sub-optimal transitions thereby increasing transition work and metabolic cost.