This work is aimed as a course text for a wide range of subjects including: kinesiology, exercise science, physical education, public health, health promotion, preventive medicine and human biology programmes. This is the first textbook to integrate research findings into the implications of physical activity levels on health. It presents readers with a conceptual framework at the beginning of each chapter, facilitating comprehension and retention; while key concepts and study questions will assist them in reviewing the material at the end of the chapter. It contains close to 300 illustrations, charts, graphs, tables and photos for ease of learning.