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Background. Understanding the motor and sensory contributions to balance function in older persons is important in order to design effective interventions to prevent falls and loss of mobility. We tested the contributions of visual and proprioceptive input, muscle strength, and age to balance performance in 110 subjects free of clinical evidence of neurologic disease (mean age 80 years). Methods. The EquiTest Sensory Organization Test was used to present sequential conditions that altered sensory input in a 2 (tactile/proprioceptive input) x 3 (visual input) design. Center of force and shear force data were recorded from the platform; the primary outcomes were loss of balance (LOB) and anterior-posterior center of force (COF) displacement as a proportion of foot length (COFD). Results. Subjects had 3.5 [+ or -] 2.7 LOB during testing. Reduction of vision input increased the odds ratio of a LOB 5.7 fold (3.9, 8.4, 95% Cl) in unstable surface conditions, but adaptation with repeated trials was substantial. The adjusted odds ratio of a LOB was 0.65 and 0.45 in the second and third trials, respectively, compared to the first. Muscle strength and age were independent predictors of LOB. Gait velocity, single stance balance, and reported difficulty with ambulation, mobility, and instrumental activities of daily living were also associated with LOB. Conclusions. Performance on clinical tests of strength, balance, and gait was associated with performance on a challenging balance test which reduced sensory input and effectiveness of motor responses. Adaptation to challenging balance conditions was substantial in this group of older subjects, but was diminished in the oldest subjects.

A study of 113 healthy men and women aged between 20 and 91 years to determine if functional base of support (FBOS) declines with age and to find out the dependability of the FBOS measure proves that FBOS is a dependable measure of voluntary postural control and that it tends to decrease in elderly persons. Decline in FBOS results in inability to perform day-to-day activities independently. FBOS can effectively predict risk due to falls among elderly persons.