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Background: It has been proved that increased motion variability can be indicative of lack of stability. Despite the extensive literature on single sit to stand/stand to sit postural transitions analysis in older people, no studies to this date have assessed the sit to stand to sit (STSTS) transition variability in older adults.Research Question: To investigate the variability in STSTS transition during the five times sit to stand (FTSS) test in older people with different fall histories.Methods: Seventy-five older (80.5 ± 7.5) and twenty-five younger (27.7 ± 6.5) subjects participated in the study. The older participants were categorized into three groups of non-fallers, once-fallers, and multiple-fallers based on their fall histories. Subjects were fitted with an IMU at their lower backs and asked to fully stand up and then sit down again five times in a row. The angular rotation of the trunk in the sagittal plane was recorded. Using the DTW method, the first STSTS transition of each subject was compared to the last transition and the variability was measured. The correlation between STSTS variability and older participants' Berg balance scale (BBS) was investigated.Results: The STSTS variability results were significantly different in older fallers (multiple-fallers and once-fallers) compared to both younger participants and older non-fallers. The results yielded a sensitivity of 85.4 % and a specificity of 83.3 % in recognizing older fallers from older non-fallers and a sensitivity and specificity of 86.7 % and 85.7 % respectively in recognizing older multiple-fallers from other older participants. The STSTS variability was found to be significantly correlated with BBS.Significance: The findings demonstrated a strong indication of variability in the STSTS transition in older fallers and a significant correlation between STSTS variability and BBS. The results suggest that variability analysis of the STSTS transition has the potential to be used for fall risk analysis in older adults. [ABSTRACT FROM AUTHOR]

Falls in older adults represent the most common cause of injuries and a major cause of mortality in this vulnerable population. The morbidity and mortality rate of falls among older people makes balance analysis in older adults very important. Therefore, this study aims to explore different metrics that can potentially be used to identify early indications of balance loss and fall risk. To that end, the motion strategies and chest and pelvis coordination of a group of younger, a group of older non-faller and a group of older faller participants while conducting the functional reach test were investigated. To analyse the motion strategies of the different participant groups, four metrics of maximum angular rotation of chest, maximum angular rotation of pelvis, time warped chest and pelvis angular rotation difference, and the mean continuous relative phase of the chest and pelvis were assessed. In this study younger participants are found to have larger maximum chest rotation, maximum pelvis rotation, and time warped chest and pelvis angular rotation difference compared to older participants. However, these metrics were not significantly different in older non-fallers compared to older fallers. Meanwhile, the mean continuous relative phase of the chest and pelvis was the only metric found to be significantly different among all three participant groups. This metric is indicative of the chest and pelvis coordination which is associated with the ability to construct proper coordination and maintain balance. The mean continuous relative phase yielded the sensitivity of 92.3% and specificity of 73.7% in recognizing older fallers from older non-fallers. The results suggest that this metric might be useful in identifying the risk of falling in older population, thus, it should be further studied in a prospective study. [ABSTRACT FROM AUTHOR]