Tijekom 21. stoljeća civilizacija se susreće s velikim promjenama kada je riječ o stilovima života. Ubrzan razvoj medicinskih znanosti i tehnologije pozitivno je utjecao na produljenje prosječnoga ljudskog života. S druge strane moderan način života dovodi do niza kroničnih nezaraznih bolesti i zdravstvenih tegoba koje se javljaju u sve ranijoj životnoj dobi i mladima narušavaju kvalitetu života. Dok su u 21. stoljeću u nekim siromašnim zemljama i dalje prisutne pothranjenost i neimaština, u bogatijim zemljama vlada epidemija preuhranjenosti. Djetinjstvo i adolescencija razdoblja su u kojima se kod mladih događa čitav niz promjena u tjelesnoj, socijalnoj i emocionalnoj domeni, ali i vrijeme stjecanja stavova prema osobnom zdravlju te životnih navika i ponašanja koja, ako nisu pravilna, čine osnovu i temelj za razvoj bolesti i tegoba koje predstavljaju ogroman teret, kako djeci i njihovim roditeljima tako i suvremenom društvu u cjelini. Pravo na zdravlje jedno je od temeljnih prava djeteta. Roditelji, škola i šira zajednica imaju moralnu odgovornost prema djeci u kontekstu njihova razvoja, obrazovanja i zdravlja. Odgovornost podrazumijeva donošenje odluka koje idu u svrhu zaštite i afirmiranja dobrobiti, uz poštovanje prava i dostojanstva svakog djeteta. Pojava rane pretilosti utječe na sve aspekte djetetova života te kao takva predstavlja značajan izazov za javno zdravlje i društvo. Životne se navike usvajaju od najranije dobi, stoga školska djeca zahtijevaju posebnu pažnju roditelja i škole kako bi se osiguralo da odrastu u zdrave mlade ljude koji će kao nositelji pozitivnih promjena oblikovati održivu budućnost.

Background and objectives: Sedentary behavior and physical activity are important determinants of musculoskeletal health, yet their relationship with gait biomechanics, explosive strength, and speed remains understudied in healthy, young populations relative to older and clinical groups. This study primarily aimed to examine the relationship between skeletal muscle mass and explosive strength in a healthy, young population, while secondarily exploring its association with sedentary behavior, physical activity, and gait biomechanical parameters. Methods: A cross-sectional study included 37 healthy young adults. Physical activity and sedentary behavior were assessed using the long-form IPAQ, body composition using bioelectrical impedance analysis, and gait, explosive strength, and speed using a wearable inertial sensor system (countermovement and plyometric jumps, parkour test). Muscle mass–strength associations were also examined with partial correlation adjusted for sex. Results: Skeletal muscle mass percentage was positively associated with countermovement jump height and power and plyometric jump height, but these associations did not remain significant after adjustment for sex. Muscle mass was not associated with total IPAQ score and was only nominally associated with IPAQ activity category, an association that did not survive correction for multiple testing. Physical activity was not associated with any gait parameter, nor did gait asymmetry differ by activity category. Sedentary behavior was not associated with any gait, strength, or speed parameter, though men reported more sitting time than women, a difference that did not remain significant after correction for multiple testing. Conclusions: In healthy young adults, the unadjusted muscle mass–strength association largely reflected shared sex differences rather than an independent relationship, underscoring the importance of accounting for sex in this population. These preliminary findings support combining questionnaire-based, body-composition, and instrumented biomechanical assessment, with statistical adjustment, in future, larger, sex-balanced research.