Physiological and psychological predictors of walking speed in older community-dwelling people

Background: Six-metre walking speed (SMWS) is a commonly used test for measuring functional performance in older people. However, apart from lower limb strength, few studies have examined the range of physiological and psychological factors that influence performance in this test. Objective: To investigate the relative contributions of a range of sensorimotor, balance and psychological factors to SMWS in a large sample of older people. Methods: 668 community-dwelling people aged 75-98 years (mean age 80.1, SD = 4.4) underwent the SMWS test as well as quantitative tests of vision, peripheral sensation, strength, reaction time, balance, fear of falling, pain and vitality. Results: Many physiological and psychological factors were significantly associated with SMWS in univariate analyses. Stepwise multiple regression analyses revealed that a composite lower limb strength measure (sum of knee extension, knee flexion and ankle dorsiflexion muscle strength scores), postural sway, leaning balance as assessed with the coordinated stability test, reaction time, edge contrast sensitivity, SF12 body pain and vitality scores and age were significant and independent predictors of SMWS. Of these measures, the combined lower limb strength measure had the highest beta weight indicating it was the most important variable in explaining the variance in SMWS. However, the other sensorimotor, balance and psychological measures each provided important independent information. The combined set of variables explained 40% of the variance in SMWS (multiple r = 0.63). Conclusions: The findings indicate that in community-dwelling older people, self-selected walking speed is influenced not only by lower limb strength but also by balance, reaction time, vision, pain and emotional well-being.