Postural instability is a common problem among older people, and it is associated with mobility impairments, activity limitation and fear of falling. The evaluation of postural control can contribute to the early detection of balance deficits and help health professionals to manage this problem to prevent falls in older adults. The aim of this study was to identify center of pressure cut-offs to differentiate between older adults with and without falls in the past 12 months. The participants were 170 older adults (mean age 67 years, 50 fallers and 120 non-fallers). Center of pressure area and sway velocity in the anterior-posterior and medio-lateral directions were assessed using a force platform during three 30s one-legged stance trials with eyes open. The mean across trials was used for analysis. The time-limit (how long the participant was able to stay in one-legged stance, up to 30s) was also assessed. Fallers had poorer postural control than non-fallers (effect size ≥ 0.52, P <0.05). The cut-offs identified were 10.3 cm² for Center of pressure area, 2.9 cm/s for velocity in the anterior-posterior, and 3.4 cm/s for medio-lateral velocity. The force platform parameters obtained an area under the curve of 0.72, with sensitivity of 78% and specificity of 68%. There were no significant differences between non-fallers and fallers for time-limit variable (17 seconds vs. 18 seconds). Force platform parameters during one-legged stance were associated with history of falls in older adults. The cut-offs obtained acceptable area under curve, sensitivity and specificity, with center of pressure area presenting the best performance to differentiate between fallers and non-fallers.

Clinical and laboratory methods have been developed to assess the different dimensions of postural control with the aim to increase the clinical relevance of decisions about balance deficit. The purpose of this study was to correlate the force platform measurements with two functional tests used to evaluate balance in elderly. A total of 124 physically independent elderly volunteers participated in this study. Subjects performed the following three tests: 1) a traditional functional balance test, named the one-leg standing test, which measures the time in seconds at this position; 2) a functional agility/dynamic balance test, which quantifies the total time in seconds that a subject can stand up from a chair and move as quickly as possible around two cones; and 3) an unipodal balance test on a force platform. The one-leg standing test yielded a mean of 12 seconds (SD=9 s), while the mean time observed in the functional agility/dynamic balance test was 26 seconds (SD=6 s). The correlations between the balance parameters of force platform and two functional tests varied between -0.28 and 0.20, which shows a weak association between them. Our results support the idea that these functional tests do not necessarily furnish the same information regarding balance mechanisms as the force platform. This study contributes to the evaluation of balance in elderly and suggests that functional tests should be used with caution especially in regards to the purposes of the research and when conducting clinical assessments of the elderly.

The purpose of this study was to assess the effect of holding an external load on the standing balance of younger and older adults with and without chronic low back pain (CLBP). Twenty participants with and 20 without CLBP participated in the study. Each group contained 10 younger (50% men) and 10 older adults (50% men). Participants were instructed to look straight ahead while standing on a force platform during two 120-second trials with and without holding an external load (10% of body mass). The center of pressure area, mean velocity, and mean frequency in the anteroposterior and mediolateral directions were measured. Older adults had worse standing balance than younger adults did (P < .001, d = 0.20). There were no significant balance differences between participants with and without CLBP within age groups during standing balance condition. However, holding the external load significantly increased postural instability for both age groups and CLBP status, with mean effect size across center of pressure variables of d = 0.82 for older participants without CLBP and d = 2.65 for younger participants without CLBP. These effects for people with CLBP were d = 1.65 for subgroup of older and d = 1.60 for subgroup of younger participants. Holding an external load of 10% of body mass increased postural instability of both younger and older adults with and without CLBP.