Association Between Ground Reaction Force in Sit-to-stand Motion and Falls in Community-dwelling Older Japanese Individuals

Objectives: Ground reaction force (GRF) during sit-to-stand motion is associated with lower extremity strength and balance function. The relationship between GRF and experience of falls has been reported; however, there are no reports on whether GRF can predict the incidence of future falls. We aimed to evaluate the ability of GRF to predict falls and compare GRF with existing predictors.

Methods: This prospective observational cohort study enrolled 456 community-dwelling older adults living in Itabashi ward who participated in health check-ups in 2016 and 2017. Participants' physical and cognitive functions were assessed, and the maximum GRF (F), F/weight (F/W), rate of force development (RFD), RFD/W (RFD/weight), and time taken to stand up were evaluated. The following year, participants were asked to report the number of falls during the year. Cox proportional hazards regression was conducted to analyze the relationship between the lowest quintile of each GRF parameter as a predictive factor for falling and assess the annual incidence of falls.

Results: Twenty-three participants reported having two or more falls in the previous year. Of all GRF parameters evaluated, only F/W was lower in the fallers than in the non-fallers. After adjusting for sex, age, lifestyle, and comorbidities, F/W was associated with falls in 1 year, and the lowest F/W group had higher risks of falls than the highest F/W group (hazard ratio 2.72, 95 % confidence interval 1.11-6.68). Other measures were not associated with falls.

Conclusions: GRF during the sit-to-stand motion might predict the incidence of future falls.