Growth and development of human muscle: A quantitative morphological study of whole vastus lateralis from childhood to adult age

Abstract

The mechanisms underlying the increase in volume of muscle tissue, and the functional development of muscle fibers from childhood through adolescence to adult age, have been studied. Cross sections of autopsied whole vastus lateralis muscle from 22 previously physically healthy males, 5 to 37 years of age, were prepared enzyme histochemically (myofibrillar ATPase) and examined morphometrically. The data obtained on muscle cross-sectional area, size, total number, and proportion of type 1 (slow-twitch) and type 2 (fast-twitch) fibers were analyzed using linear regression techniques. The results show that the increase in muscle cross-sectional area from childhood to adult age is caused by an increase in mean fiber size. This is accompanied by a functional development of the fiber population: the proportion of type 2 fibers increases significantly from the age of 5 (approx. 35%) to the age of 20 (approx. 50%), which, in the absence of any discernible effect on the total number of fibers, is most likely caused by a transformation of type 1 to type 2 fibers.

Skeletal age and explosive strength in young volleyball players

“…In fact, some mechanisms can be attributed to explain the obtained values for young people explosive strength during biological development. hey include the largest responses of anabolic hormones, such as testosterone 20 and structural changes in muscle architecture, resulting signiicant changes in type I to type II ibers proportion 21,22 , observed in younger age. Volver et al 23 , further complement that the anabolic androgenic actions in the pubertal period stimulate the development of type II muscular ibers, responsible for explosive force generation.…”

Muscle fibre type composition in infant and adult populations and relationships with obesity

“…22±25 Finally, in a young group of subjects (aged 5±20 y), Type 2 ®bre type proportion increased with age. 31 However, most of the studies have not differentiated between Type 2a and Type 2b ®bres. The distinction is important given the very different oxidative capacities, and ability to use lipid for energy, between these ®bre types.…”

Relationships between Yo-Yo Intermittent Recovery Tests and Development of Aerobic and Anaerobic Fitness in U-13 and U-17 Soccer Players

“…In this study, FFM in U-13 group was signiˆcantly lower than that in U-17 group (Table 1). In general, young boys exhibit great development in muscle (especially fast twitcĥ ber, Lexell et al, 1992) associated with the muscle hypertrophy caused by a rise in anabolic hormones from sexual maturation through puberty (Malina and Bouchard, 1991). The fast twitchˆber is excellent in the anaerobic energy system.…”