Functional Properties of Skeletal Muscle

Abstract

Publisher Summary The majority of studies on the anatomy and contractile characteristics of fish skeletal muscle have focused on species that employ some degree of axial body undulation to power locomotion, typically anguilliform, carangiform, subcarangiform, and thunniform. Fish size, the location of the muscle in the fish, and temperature have pronounced effects on many aspects of muscle contraction. In many species, but not all, there is notable axial variation in the speed of red muscle within an individual, with the more‐anterior muscles tending to be faster than the posterior. It is suggested that this may serve to compensate for the smaller strains experienced in the anterior myotomes of many fishes during swimming, allowing the muscles there to produce relatively more power than if they had the slower kinetics of more‐posterior muscles. There is also often notable axial variation in power output of red muscle in swimming fishes, but this is associated more with the manner in which the muscle is used than with its inherent abilities. Radial variation in muscle speed has also been noted in tuna, in which the deeper red fibers are faster and perhaps better equipped to work when warm. This variability in the contractile characteristics of a given fiber type within an individual appears unique to the fish, and may have a basis in compensating for axial variation in strain and bending kinematics, or in promoting axial variation in muscle function during swimming.