Older adults adopt a conservative postural control strategy during sit-to-walk transitions, prioritizing enhanced stability by restricting forward horizontal momentum and prolonging movement duration, which elucidates characteristics underlying fall risks.
Key Findings
Results
Peak horizontal momentum showed significant differences between young and older adult groups across the entire sit-to-walk phase.
Independent samples t-tests, statistical parametric mapping, and phase-average comparisons were used to assess differences.
Differences in peak horizontal momentum (HM) were significant across the entire phase (p < 0.05).
Older adults restricted forward horizontal momentum as part of a conservative postural control strategy.
Prolonged movement duration was also observed in the older adult group.
Results
The anteroposterior margin of stability differed significantly between young and older adults during the extension and swing phases of sit-to-walk.
Anteroposterior margin of stability (MOS) differences were significant during the extension and swing phases (p < 0.03).
MOS was not reported as significantly different during all phases of the STW transition.
The MOS is used as a measure of dynamic stability control during the movement.
Results
Knee range of motion and center of pressure excursion velocity differed significantly between groups only during the unloading phase.
Significant differences in knee range of motion were found only in the unloading phase (p < 0.05).
Center of pressure excursion velocity also showed significant between-group differences only during the unloading phase (p < 0.05).
These lower-limb kinematic differences were assessed using independent samples t-tests and statistical parametric mapping.
Results
In young adults, margin of stability, horizontal momentum, and joint kinematics demonstrated significant strong negative correlations, whereas these correlations were attenuated in older adults.
In the young group, correlations among MOS, HM, and joint kinematics were significant and strong negative (r < -0.5, p < 0.05).
In the older adult group, these correlations were 'generally attenuated,' suggesting a decoupling of the coordinative relationship between momentum and stability variables.
Correlation analyses were used as a supplementary method alongside group comparisons.
The attenuation of correlations in older adults may reflect altered motor control strategies.
Discussion
Older adults adopt a conservative postural control strategy during sit-to-walk transitions that prioritizes stability over momentum generation.
The conservative strategy was characterized by restricted forward horizontal momentum and prolonged movement duration.
This strategy was interpreted as prioritizing enhanced stability during the sit-to-walk transition.
The authors identified this strategy as underlying characteristics associated with fall risk in older adults.
The findings were described as providing 'a scientific rationale for the design of targeted biomechanical interventions.'
Background
The sit-to-walk transition was used as a paradigm to elucidate overall motor control strategies and fall risk mechanisms.
STW was described as 'a highly prevalent functional movement in activities of daily living' and 'a pivotal task paradigm for elucidating overall motor control strategies.'
The study comparatively evaluated stability control characteristics between young and older adult groups.
Multiple biomechanical measures were included: MOS, HM, knee range of motion, and center of pressure excursion velocity.
The study used independent samples t-tests, statistical parametric mapping, phase-average comparisons, and correlation analyses.
What This Means
This research examined how people of different ages control their balance and movement when transitioning from sitting to walking — an everyday activity that becomes increasingly risky with age. The researchers compared younger and older adults on several biomechanical measures, including how much forward momentum they generated, how their knees moved, and how stable their center of mass remained relative to their base of support throughout the movement.
The study found that older adults generated less forward momentum and took longer to complete the sit-to-walk movement compared to younger adults. Older adults also showed less coordinated relationships between their momentum, stability, and joint movements — meaning the body systems that work together efficiently in younger people appear to become less integrated with age. Younger adults showed strong, consistent links between how they generated momentum and how they maintained stability, whereas these links were weaker in older adults. Differences in knee movement and how quickly the center of pressure shifted were particularly notable during the early 'unloading' phase of the movement.
This research suggests that older adults compensate for reduced motor control by moving more cautiously and slowly during the sit-to-walk transition, which may protect them in the short term but could also reflect underlying vulnerabilities that increase fall risk. Understanding these age-related differences in movement strategy could help researchers and clinicians design better targeted exercises or assistive technologies to improve safety and mobility in older populations.
Zhang G, Li F, Zhao R, Chen D, Sun D, Song Y, et al.. (2026). Dynamic stability in sit-to-walk transition: A quantitative analysis based on age-related momentum distribution and lower extremity kinematics.. Acta of bioengineering and biomechanics. https://doi.org/10.37190/abb/230880