Optimum angle of force production temporarily changes due to growth in male adolescence

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


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.

Original languageEnglish
Article number20
Issue number1
Publication statusPublished - 2021 Jan


  • Children
  • Force–angle relationship
  • Growth spurt
  • Isokinetic muscle strength
  • Maximal voluntary contraction
  • Muscle–tendon unit

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health


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