Abstract
This study aimed to clarify the relationship between the subjective evaluation of lower limb strength and objective evaluation using a single sit-to-stand (STS) movement in community-dwelling older adults. A total of 162 participants were asked about their self-perceived lower limb muscle strength (subjective strength), and the peak ground reaction force during a single STS movement, normalized to body weight (stand-up index, SUI), was recorded as an objective measure. The consistency between the subjective and objective evaluations of lower limb strength was analyzed. The results showed that only 45.0% of the participants were consistent, while 38.3% overestimated and 16.7% underestimated their strength, indicating discrepancies in more than half of the participants. The prevalence of frailty was the highest in the group that had a consistent evaluation. However, frail individuals were also observed in both the groups that overestimated (23.0%) and underestimated (15.4%) their evaluation. Overestimation was associated with the potential risk of falls and injuries owing to excessive confidence in physical ability. In contrast, the group that had an underestimated evaluation objectively maintained good strength, but psychological and social factors may have contributed to their reduced activity levels. Among the indicators of physical function, significant group differences were found only for SUI, with the group that had an underestimated evaluation showing the highest values. These findings suggest that SUI is a simple, safe, and practical index for quantifying lower limb strength and visualizing discrepancies with subjective perception. The combined use of objective physical fitness measurements and subjective evaluations may support the early identification of high-risk individuals and contribute to the development of strategies for frailty and fall prevention.
