The emergence of age-related deterioration in dynamic, but not quiet standing balance abilities among healthy middle-aged adults.

The purpose of the present study was to quantify differences in lower extremity reach performance, static posturography and gait outcomes between young (20-39 years), middle-aged (40-59 years) and older (60-79 years) adults using identical tests and parameters. This was a cross-sectional study with three parallel groups (young [20-39 years] vs. intermediate [40-59 years] vs. older [60-79 years] adults). In a randomised order each participant completed: (i) static posturography, (ii) lower extremity reach performance, and (iii) gait assessment. Changes in balance between age groups were analysed using analysis of variance (ANOVA). Additionally, correlational analysis was used to identify relationships between age and outcome measures. Centre of pressure (COP) movement was greater in older compared to intermediate-aged (d = 0.50-2.40) and young (d = 0.54-2.61) adults (p < 0.001). Reduced lower extremity reach distance was found in older compared to intermediate-aged (d = 1.28-3.60) and young (d = 2.09-3.87) adults (p < 0.001), while young adults demonstrated greater reach distances than intermediate (d = 0.64-1.74) aged adults (p < 0.001). Correlational analysis revealed moderate to strong positive correlations between age across the adult life span (20-79 years) for all COP metrics and lower extremity reach outcomes. When correlational analyses were performed only in the young and middle-aged groups (20-59 years), coefficients were weak and not significant for the COP, but remained moderate for lower extremity reach performance. Lower extremity reach performance reveals earlier age-related declines in postural stability that are not evident during quiet standing tasks of varying difficulty. These findings should contribute to the early identification of potential balance deficits in those where balance problems do not yet exist, which will assist clinical decision making with respect to timely implementation of fall prevention strategies.