Landing Biomechanics Across Childhood: A Shift in Energy Dissipation From Soft Tissues to Lower Limb Joints.

This study aims to examine how landing biomechanics, including the contribution of joints and soft tissues, change throughout childhood and under increasing mechanical demand during double-legged landings. Children aged 3-12 years and adults performed landings from four heights: 10, 30, 50, and 70 cm. Ground reaction forces and full-body kinematics were used to calculate total mechanical work as well as the work performed by lower limb joints, upper limb joints and soft tissues. Biomechanical strategies were further assessed by estimating stiffness and damping throughout landing. Across all ages, participants performed a similar amount of total mechanical work and adjusted it appropriately with increasing mechanical demand. However, younger children relied more on soft tissues to dissipate energy, while the relative contribution of lower limb joints increased gradually with age until adulthood. Additionally, with increased mechanical demand, the relative contribution of lower limb joints decreased, whereas that of upper limb joints increased. This redistribution was accompanied by changes in biomechanical behavior: stiffness during the initial landing phase was greater in young children, while stiffness after peak force was independent of age but decreased as mechanical demand increased. In summary, although children as young as 3 years can land from a jump and adjust their behavior according to the mechanical demand, strategies continue to mature throughout childhood. Younger children exhibit stiffer behavior during the initial phase of landing and rely more on soft tissues to dissipate energy, whereas older children and adults show reduced stiffness and greater reliance on lower limb joints.