Muscle Biophysics

Muscle contraction has been the focus of scientific investigation for more than two centuries, and major discoveries have changed the field over the years. Early in the twentieth century, Fenn (1924, 1923) showed that the total energy liberated during a contraction (heat + work) was increased when the muscle was allowed to shorten and perform work. The result implied that chemical reactions during contractions were load-dependent. The observation underlying the “Fenn effect” was taken to a greater extent when Hill (1938) published a pivotal study showing in details the relation between heat production and the amount of muscle shortening, providing investigators with the force-velocity relation for skeletal muscles. Subsequently, two papers paved the way for the current paradigm in the field of muscle contraction. Huxley and Niedergerke (1954), and Huxley and Hanson (1954) showed that the width of the A-bands did not change during muscle stretch or activation. Contraction, previously believed to be caused by shortening of muscle filaments, was associated with sliding of the thick and thin filaments. These studies were followed by the classic paper by Huxley (1957), in which he conceptualized for the first time the cross-bridge theory; filament sliding was driven by the cyclical interactions of myosin heads (cross-bridges) with actin. The original cross-bridge theory has been revised over the years but the basic features have remained mostly intact. It now influences studies performed with molecular motors responsible for tasks as diverse as muscle contraction, cell division and vesicle transport.

Muscle contraction has been the focus of scientific investigation for more than two centuries, and major discoveries have changed the field over the years. This book centers mostly on mechanical studies, dealing with force production and regulation; it gathers studies performed by scientists who have used diverse muscle techniques, and who have shaped the field of muscle contraction throughout the past years. Starting with theoretical approaches to understand myosin molecule function and energetics, this book covers experimental work performed with single molecules, and discusses results from studies investigating basic mechanisms of contraction, using (mostly in order of appearance) isolated sarcomeres, myofibrils, and fibers are presented. The last chapters summarize studies investigating the effects of acute and chronic adaptations, including weakness and muscle disease. Muscle Biophysics represents an excellent source of information for readers intending to understand the mechanics of muscle contraction, and is a fascinating collection of chapters that will hopefully stimulate young investigators to pursue research in this exciting field of research.