Continuum of Physical Activity strength trained endurance trained Load controls inactivity Frequency of recruitment Muscle is plastic! Muscle “adapts” to meet the habitual level of demand placed on it, i.e. level of physical activity. Level of physical activity determined by the frequency of recruit- ment and the load. Increase muscle use – endurance training – strength training (cannot be optimally trained for both strength and endurance) Decrease muscle use – prolonged bed rest –limb casting –denervation –space flight. Adapted from Faulkner, Green and White In: Physical Activity, Fitness, and Health,Ed. Bouchard, Shephard and Stephens Human Kinetics Publishers, 1994

Vander's Human Physiology, Twelfth Edition, carries on the tradition of clarity and accuracy, while refining and updating the content to meet the needs of today's instructors and students. The twelfth edition features a streamlined, clinically oriented focus to the study of human body systems. It has also responded to reviewer requests for more clinical applications. Chapter 19 was new for the eleventh edition, with three complete case studies. The twelfth edition will contain an additional new case study. Additional Physiology Inquiries have been added to many figures throughout the chapters. These critical-thinking questions are just one more opportunity to add to the student's learning experience. Motor unit remodeling with aging Central nervous system Muscle Motor neuron loss AGING • Fewer motor units • More fibers/motor unit Ghost” fiber 3 days after initial injury Faulkner, Brooks and Zerba (1995) J Gerontol 50:B124-B129.

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Only lengthening contractions result in damaged fibers * control 20 passive isometric lengthening * different from zero (p<0.05) 15 Injured fibers (% total) 10 5 0 Other Measures of Contraction-Induced Injury • immediate mechanical disruption observed by EM. • enzyme release from degenerating muscle fibers • in human beings, subjective reports of muscle soreness • in the absence of fatigue, a decrease in the development of force Koh & Brooks (2001) Am J Physiol 281:R155-R161. But first, we should explain that the current authors (Art Vander, James Sherman and Dorothy Luciano) are still very much alive, and well. They are simply ready to retire from authoring the text-- which presents us with an opportunity to bring in a fantastic new team to continue the success of the text! The original author team will still be involved in future editions and will continue to serve as "consultants" on their book.

Performance Declines with Aging --despite maintenance of physical activity 100 80 60 Performance (% of peak) 40 Shotput/Discus Marathon 20 Basketball (rebounds/game) 0 20 30 40 50 60 10 Age (years) D.H. Moore (1975) Nature 253:264-265. NBA Register, 1992-1993 Edition Microstructure Modified from Squire, Muscle: Design, Diversity, and Disease Benjamin/Cummings, 1986 Originally from Lazarides (1980) Nature 283:249-256. In 1970, Drs. Vander, Sherman and Luciano created what has long been regarded by many as the most complete, readable and up-to-date Human Physiology textbook in the world. I am honored and thrilled to take over the reigns of this wonderful textbook, as it moves into the rapidly expanding realm of 21st century physiology. Together with my outstanding co-authors, Dr. Hershel Raff and Dr. Kevin Strang, we eagerly look towards the future with the goal of continuing our predecessors' standards of excellence, while making the text even more attractive to the ever-widening audience of physiology students." Eric Widmaier (Boston University), Hershel Raff (Medical College of Wisconsin), and Kevin Strang (University of Wisconsin) have taken on the challenge of maintaining the strengths and reputation of Vander's Human Physiology: The Mechanisms of Body Function. Moving beyond the listing of mere facts, it stresses the causal chains of events that constitute the mechanisms of body function. The fundamental purpose of this textbook is to present the principles and facts of human physiology in a format that is Vander's Human Physiology, thirteenth edition, carries on the tradition of clarity and accuracy, while refining and updating the content to meet the needs of today's instructors and students. The thirteenth edition features a streamlined, clinically oriented focus to the study of human body systems. It has also responded to reviewer requests for more clinical applications. Physiology Inquiries are maintained throughout the chapters. These critical-thinking questions associated with figures are just one more opportunity to add to the student's learning experience. Increased use: strength training Early gains in strength appear to be predominantly due to neural factors…optimizing recruitment patterns. Long term gains almost solely the result of hypertrophy i.e. increased size.The Online Learning Center is designed to enhance your learning. Book-specific content such as quizzing, case studies, objectives, and web links can all be accessed by choosing from the list to the left. These materials are designed to help you succeed in your course. Endurance training Little hypertrophy but major biochemical adaptations within muscle fibers. Increased numbers of mitochondria; concentration and activities of oxidative enzymes (e.g. succinate dehydrogenase, see below). Succinate dehy- drogenase (SDH) activity: Low activity light High activity dark Control 12-weeks treadmill running Images courtesy of John Faulkner and Timothy White Homeostasis: A Framework for Human Physiology Chemical Composition of the Body Cellular structure, proteins, and Metabolism Movement of Molecules Across Cell Membranes Control of Cells by Chemical Messengers Neuronal Signaling and the Structure of the Nervous System Sensory Physiology Consciousness, the Brain, and Behavior Muscle Control of Body Movement The Endocrine System Cardiovascular Physiology Respiratory Physiology The Kidneys and Regulation of Water and Inorganic Ions The Digestion and Absorption of Food Regulation of Organic Metabolism and Energy Balance Reproduction Defense Mechanisms of the Body Medical Physiology: Integration Using Clinical Cases. Here's a quote from new lead author Eric Widmaier about the team's plans for the future of the Vander text... Chemomechanical coupling – conversion of chemical energy (ATP about 7 kcal/mole) into force/movement. • ATP is unstable thermodynamically • Two most energetically favorable steps: • 1. ATP binding to myosin • 2. Phosphate release from myosin • Rate of cycling determined by M·ATPase activity and external load Adapted from Goldman & Brenner (1987) Ann Rev Physiol 49:629-636.