To generalize

the current results, however, further investigation involving muscle volume measurements with more sophisticated techniques such as magnetic resonance imaging is needed. Conclusion The current results demonstrated that muscle quality, expressed as maximal inhibitor bulk joint torque relative to muscle volume, is not different between prepubescent and pubescent boys in the knee extensors and ankle plantar flexors. It suggests that maturation has little influence on the strength-size relationship in the lower extremity muscles around puberty. The current results were obtained from a cross-sectional survey. In a longitudinal survey, TQ/MV in the knee extensors is constant for the 6-month period of preadolescence [19]. However, to the best of our knowledge, less information on the longitudinal change in TQ/MV in the period of adolescence is available from earlier findings. To clarify, this is important for pediatric exercise physiology, and further investigation based on longitudinal survey is needed. Abbreviations BMI:

Body mass index; KE: Knee extensors; KET: Knee extension torque; L: Limb length; LBM: Lean body mass; MT: Muscle thickness; MV: Muscle volume; MVC: Maximal voluntary isometric joint torque; PCSA: Physiological cross-sectional area; PF: Ankle plantar flexors; PFT: Ankle plantar flexion torque; PH: Stage of pubic hair; TQ: Maximal joint torque; % fat: Percent body fat. Competing interests The authors declare that they have no competing interests. Authors’ contributions YF carried out the anthropometric measurement, performed the statistical analysis and drafted the manuscript. YT conceived of the study, and participated in its design and coordination and helped to draft the manuscript. TY and EF carried out the strength measurement and helped to perform the statistical analysis. MY and HK supervised the survey, participated in the design of the study and performed the statistical analysis. All authors read and approved the final manuscript. All authors read and approved

the final manuscript.

Obesity and overweight are increasing in prevalence in developed Dacomitinib countries as a result of changing dietary habits and a lack of physical activity (PA) [1-4]. Both conditions are caused by a chronic imbalance between energy intake (EI) and expenditure (EE). A positive balance between EI and EE is a key factor in weight gain caused by overfeeding or decreasing activity energy expenditure (AEE). Most of the accumulation of excess energy is stored as lipid, mainly triglycerides, with overfeeding [5]. Lipid is ideal for long-term energy store, with little water accumulation in humans. Therefore, huge quantities of triglycerides can be stored with increasing adipocyte size and number during positive energy balance [6,7].