Determinants of static balance performance across lifespan vary with sensory conditions

Age-related changes in balance control generally describes a U-shaped relation, with lesser stability observed at both ends of the lifespan. However, the determinants that drive this relation are still not clear and may vary with the sensory conditions in which the postural task is performed. This cross-sectional study investigated age-related changes in static balance control from childhood to old age and investigated potential factors underlying balance performance. One hundred fifty-seven participants were divided into six age groups (6-14; 14-17; 18-39; 40-59; 60-75; >76 yrs). Mean velocity (MV) of the centre of pressure was recorded while participants stood upright under four sensory conditions: eyes open or closed on stable (top plate of the force platform) and unstable (foam mat) surface. Surface electromyography of the soleus, gastrocnemius medialis, and tibialis anterior was recorded during postural tasks. Ankle joint position sense (aJPS) and maximal isometric force of plantar flexors and dorsiflexors were also measured. Group differences in MV were observed across all conditions (p < 0.001), with greater MV in children (6-14 yrs) and older adults (> 60 yrs), especially on the unstable surface for older adults. Regression analyses showed that greater aJPS acuity contributes to stabilize CoP on rigid support, whereas an increase in leg muscle activity may help compensate for the inherent instability induced by the compliant surface. Chronological age appears as an independent predictor of static balance control only in this latter condition. These results highlight the necessity of using various sensory conditions to assess balance performance and its underlying determinants across lifespan.