Mobility performance and its sensory, psychomotor and musculoskeletal determinants from age 75 to age 80

Background and aims : Prospective studies on the simultaneous effects of multiple determinants on objectively assessed mobility are few. The aim of this study was to analyse mobility performance, its stability and sensory, psychomotor and musculoskeletal determinants in an older population from age 75 to age 80. Methods : Sixty-three men and 121 women aged 75 participated at baseline and, five years later, in the follow-up phase of this population-based prospective study. Maximal walking speed and step-mounting height were assessed at baseline and follow-up. Maximal isometric knee extension strength, standing balance on force platform, reaction time, visual acuity and limitations in range of motion (ROM) of hips and knees were assessed at baseline. Structural equation modeling was used to analyse the associations. Results : The stability of mobility performance from baseline to the five-year follow-up was high (coefficient 0.80 in men, 0.78 in women). In men, knee extension strength, standing balance, ROM limitations and visual acuity explained 69% of the variation in mobility performance at baseline and, indirectly, 59% of that variation at follow-up. Among women, knee extension strength, standing balance, visual acuity and reaction time explained 52% of the variation of mobility performance at baseline and, indirectly, 30% at the five-year follow-up. Conclusions : Results indicate that the predictive effects of sensory, psychomotor and musculoskeletal functions on mobility performance extend over five years in older people. In seeking to prevent mobility limitations, vision, reaction time and lower extremity ROM need to be targeted, in addition to muscle strength and balance.