CHAPTER 1 - Structural and Functional Organization of Skeletal Muscle

Abstract

This chapter discusses the structural and functional organization of skeletal muscle, mechanical properties of skeletal muscle, and effects of altered muscular activity on skeletal muscle. Muscles are biological machines that convert chemical energy—derived from the reaction between food substrate and oxygen—into force production and mechanical work. The mechanical properties of skeletal muscle are expressed in terms of both its force and contractile speed generating capability. Calcium levels in the cytoplasm are responsible for regulating the contraction response. Under most physiological conditions, skeletal muscles contract tetanically rather than in twitch fashion. The most fundamental mechanical property of skeletal muscle is its force–velocity relationship, which describes the muscle's ability to shorten as a function of the force it generates during a given isotonic contraction. Skeletal muscle has the capacity to adapt its morphological, biochemical, and functional properties in accordance with the functional demands imposed on it. The functional demand varies from endurance exercise and strength training to limb immobilization.