Optimum Angle of Force Production Temporarily Changes Due to Growth in Male Adolescence.

Junya Saeki,Toshihiro Maemichi,Ayahiro Suzuki,Suguru Torii,Satoshi Iizuka,Hiroaki Sekino

doi:10.3390/children8010020

Junya Saeki, Toshihiro Maemichi + Show 4 more

Open Access

https://doi.org/10.3390/children8010020

Copy DOI

Abstract

The peak increase in lean mass in adolescents is delayed from peak height velocity (PHV), and muscle flexibility temporarily decreases as bones grow. If the decrease in muscle flexibility is caused by muscle elongation, the relationship between the exerted torque and the joint angle could change in adolescents. The purpose of this study was to investigate the change in the optimum angle of force production due to growth. Eighty-eight healthy boys were recruited for this study. Isokinetic knee extension muscle strength of the dominant leg was recorded. The outcome variable was the knee flexion angle when maximal knee extension torque was produced (optimum angle). The age at which PHV occurred was estimated from subjects’ height history. We calculated the difference between the age at measurement and the expected age of PHV (growth age). A regression analysis was performed with the optimal angle of force exertion as the dependent variable and the growth age as the independent variable. Then, a polynomial formula with the lowest p-value was obtained. A significant cubic regression was obtained between optimum angle and growth age. The results suggest that the optimum angle of force production temporarily changes in male adolescence.

Highlights

The incidence of sports injuries in adolescents increases until 15 to 16 years of age and decreases thereafter [1,2]
The cause has been considered to be influenced by bone mineral density (BMD) because the whole body BMD of the adolescent decreases when peak bone length increases, and many distal radius fractures occur at this time [3]
The lean mass peak increase in adolescents is delayed from peak height velocity (PHV) [4], and muscle flexibility temporarily decreases with increasing bone length [5,6]

Summary

Introduction

The incidence of sports injuries in adolescents increases until 15 to 16 years of age and decreases thereafter [1,2]. While whole body BMD recovers after its lowest point at around 13 years, the time of peak height velocity (PHV) [3], the incidence of sports injury increases until 15 to 16 years of age [1]. The lean mass peak increase in adolescents is delayed from PHV [4], and muscle flexibility temporarily decreases with increasing bone length [5,6]. Considering the above background, the relationships between exerted torque and joint angle may change during the muscle elongation period when bone growth precedes muscle growth. Change in the force–angle relationship has not been investigated

Objectives

Methods

Conclusion