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Growth and development of human muscle: A quantitative morphological study of whole vastus lateralis from childhood to adult age
Author(s) -
Lexell Jan,
Sjöström Michael,
Nordlund AnnSofie,
Taylor Charles C.
Publication year - 1992
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880150323
Subject(s) - myofibril , vastus lateralis muscle , anatomy , fiber type , muscle fibre , biology , fiber , population , medicine , endocrinology , chemistry , skeletal muscle , environmental health , organic chemistry
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 crosssectional 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.