Abstract
The purpose of this study was to investigate growth changes in human plantar flexor
muscle and tendons. In addition, we ascertained whether growth changes in muscle and
tendon were more closely related to skeletal age than chronological age. 22 elementary
school children (ESC), 19 junior high school students (JHS), and 23 young adults (ADT)
men participated in this study. Maximal strain and hysteresis of tendon structures
and cross-sectional area of Achilles tendon were measured using ultrasonography. In
addition, skeletal age was assessed using Tanner-Whitehouse III method. Maximal strain
of ESC was significantly greater than that of other groups, while no significant difference
was observed between JHS and ADT. There was no difference in hysteresis among 3 groups.
Relative cross-sectional area (to body mass2/3) of ADT was significantly smaller than that of other groups. For ESC and JHS, measured
variables of muscle and tendon were significantly correlated to both chronological
and skeletal ages. These results suggested that immature musculoskeletal system was
protected by more extensible and larger tendon structures in ESC and only by larger
tendon structures in JHS, respectively. Furthermore, there were no differences in
correlation coefficient values between measured variables of muscle and tendon and
chronological or skeletal ages.
Key words
strain - hysteresis - cross-sectional area - skeletal age