Modeling developmental changes in strength and aerobic power in children

Area of Science:

• Pediatric Exercise Science
• Human Growth and Development
• Biomechanical Modeling

Background:

• Understanding developmental changes in physical capabilities like strength and aerobic power is crucial for pediatric health and performance.
• Previous models often used additive structures, which may not fully capture the complex interplay of factors like body size during growth.

Purpose of the Study:

• To compare two distinct multilevel model structures—additive polynomial and multiplicative allometric—for describing longitudinal changes in children's strength and aerobic power.
• To determine which model provides a superior fit and more biologically plausible representation of developmental trajectories.

Main Methods:

• Utilized data from two published longitudinal studies on children's physical development.
• Applied multilevel regression analyses comparing maximum log-likelihood criteria for model selection.
• Investigated the relationship between aerobic power, strength (quadriceps and biceps), body mass, age, and peak height velocity (PHV).

Main Results:

• The multiplicative allometric model demonstrated superior fit compared to the additive polynomial model.
• Aerobic power was found to develop proportionally to body mass (m1/3).
• Quadriceps and biceps strength increased proportionally to body size, with an additional age-related component around PHV, exhibiting sex-specific patterns.

Conclusions:

• The allometric model provides a more accurate and plausible framework for analyzing developmental changes in children's physical fitness.
• Boys show enhanced relative strength gains around PHV, whereas girls' relative strength gains are less pronounced or decrease for biceps.
• These findings highlight the importance of considering body size allometry and age-sex interactions in pediatric exercise science.