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

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.

Growth until Peak Height Velocity Occurs Rapidly in Early Maturing Adolescent Boys

“…The main finding was that the early maturation group had a higher growth tempo from TOA to PHVA than the middle and late maturation groups. The PHVA acquired as the standard for maturity status was 13.29 ± 0.11 years, which is close to what has been reported previously for Japanese subjects [ 2 , 3 , 20 ]. However, Nariyama et al [ 21 ] reported that the PHVA of Japanese soccer players was 13.65 ± 1.09 years, which is later than in other sports (Baseball: 13.10 ± 0.96; Basketball ± 12.84 ± 1.12; Volleyball: 13.17 ± 0.80 years).…”

The burden of injuries according to maturity status and timing: A two‐decade study with 110 growth curves in an elite football academy

“…In line with previous data (Bult et al, 2018; Johnson et al, 2020), our results showed an increase in overall injury burden with advanced maturity status. Anthropometrical (Kemper et al, 2015; Rommers et al, 2020; Wik, Martínez‐Silván, et al, 2020), neuromuscular (Read et al, 2018b; Read, Oliver, de Ste Croix, Myer, & Lloyd, 2016; Saeki et al, 2021), and physiological (e.g. mechanical properties) (Radnor et al, 2018) changes induced by PHV may contribute to increased injury risk from circa‐PHV onwards.…”

“…Nevertheless, muscle injuries had a larger impact in post‐PHV and adult players. After bone‐plate and apophysis ossification (Malina & Bouchard C, 2004), muscle might be the structural point of failure for neuromuscular (Read et al, 2016; Read et al, 2018b; Saeki et al, 2021), and physiological (Radnor et al, 2018) alterations induced by PHV, resulting in increased burden post‐PHV. Further, re‐injuries and higher demands in older players (Read et al, 2018a) also may influence muscle injury burden, especially in adults.…”

Peak Height Velocity Affects Injury Burden in Circa-PHV Soccer Players

“…We hypothesized that fast PHV might have resulted in more intense neuromuscular [20][21][22][23] and physiological alterations [40] leading to increased muscle [20] and joint/ligament [22,23] injury risk in circa-and post-PHV. However, our study did not find significant differences in these injuries among players with fast, average, and slow PHV.…”

“…Besides, no study has considered studying PHV (maximal growth-rate) as an injury risk-factor in circa-and post-PHV periods. PHV leads to alterations in force production [20,21] and loss of movement coordination [22,23], which can also remain in post-PHV [21,22]. As a result, PHV might influence injury burden in both circa-and post-PHV periods.…”