JMIR Publications

ABSTRACT

Background:

Stair negotiation, a complex motor task, is significantly affected by aging, yet the impact of disability on these changes remains underexplored.

Objective:

To evaluate the lower limb joint positions, velocities and the center of mass (CoM) displacement and velocity during stair negotiation and transitions with floor in older adults with and without functional disability.

Methods:

Community-dwelling individuals aged 60 and older participated in the study. Lower limb tridimensional joint positions and velocities during the instances of foot contact with step or foot leaving the step, and foot contact with floor or foot leaving the floor, the joint range of motion (ROM), angular velocity range (ΔVelocity) and the CoM displacement and ΔVelocity were assessed during stair ascend and descend and transitions floor-to-stair (F-S) and stair-to-floor (S-F) through an optoelectronic system. Principal component analysis assessed different group of variables to compute principal component models (PCMs). PCMI included position and velocity at the instant of step contact and PCMII for the instant of step leaving. The PCM III included range variables during stair negotiation and PCM IV CoM variables also during stairs negotiation. PCM V assessed the instant of floor contact and PCM VI the instant of leaving the floor. PCM VII included ranges during F-S and S-F and PCM VIII the CoM variables during transitions. Principal components (PCs) with eigenvalues above one were extracted, and variables loading above 0.7 were retained. The older adults sample was classified with or without disability based on limitations in at least two of the following indicators: handgrip strength, basic and instrumental activities of daily living, balance, and self-reported health and PCs group differences were assessed using the Mann-Whitney U test.

Results:

PCA of 240 kinematic variables led to the selection of forty one kinematic parameters (loadings >0.7) retained in the PCMs, primarily associated with angular velocities of the hip and knee in the sagittal plane. CoM displacement and ΔVelocity PCMs IV and VIII retained sagittal plane parameters for both stair ascend and descend, as transverse plane on floor transition cycles. Twelve PCs significant differenced older adults with disability (n=25) and without disability (n=35).

Conclusions:

Changes in sagittal plane hip and knee angular velocity and mediolateral and vertical CoM displacement and velocity, were identified in older adults with disability during stair negotiation and transitions. These insights carry implications for the development of targeted interventions aimed at supporting the stability and mobility of older adults, especially those with functional disability Clinical Trial: ClinicalTrials.gov NCT05611723