Portal de Periódicos da CAPES

Skeletal muscle fibre types, enzyme activities and physical performance in young males and females

1978; Wiley; Volume: 103; Issue: 2 Linguagem: Inglês

10.1111/j.1748-1716.1978.tb06208.x

1365-201X

Paavo V. Komi, J. Karlsson,

Cardiovascular and exercise physiology

Abstract Differences in skeletal muscle characteristics, metabolic profiles and functional performance between males and females were investigated using young (15–24 yrs) male and female twins as subjects. The comparison included such variables as anthropometry, muscle strength, mechanical power, maximum oxygen uptake, electrical activation of muscle, muscle fibre composition (m. vastus lateralis), and activities of several skeletal muscle enzymes. The results disclosed the following primary differences between males and females: In the various functional tests the performance of females was from 61.1 to 84.6% of that in males; distribution of slow twitch fibres in m. vastus lateralis of the females (49.1 ± 7.7%) was lower (p<.05) than that of the males (55.9 ± 11.9); activities of enzymes Ca 2+ stimulated ATPase, CPK, phosphorylase and LDH ± were higher (p <.05‐.01) in the males, whereas the distribution pattern of LDH‐1 isozyme was higher (p <05) in the females. A pronounced difference between the two groups was an almost 100% longer rise time of isometric force in females. It is concluded that the males as compared to the females demonstrate higher aerobic and strength performance capacity, more efficient neuromotoric output during contraction, more slow twitch muscle fibres and more pronounced contractile and glycolytic profiles in the skeletal muscles.