The Association Between Foot-Ankle Mechanical Leverage and Instability During Walking in Older and Younger Adults.

No age effect was found on peak external moment arms due to ground reaction forces at the foot and ankle.

• The study compared older and younger adults on mechanical leverage metrics during walking
• Peak external moment arms due to ground reaction forces did not differ significantly between age groups
• This suggests morphological changes in the foot and ankle with aging do not necessarily alter the external mechanical leverage available

Older adults exhibited smaller peak ankle moments compared to younger adults during walking.

• Despite no age difference in external moment arms, older adults showed reduced peak ankle moments
• This finding suggests older adults may have reduced capacity to generate ankle joint moments independent of changes in external leverage
• The difference in ankle moments was observed during habitual walking conditions

Older adults showed larger ranges of frontal plane whole-body angular momentum than younger adults.

• Frontal plane whole-body angular momentum range was used as a measure of dynamic balance during walking
• Larger ranges of whole-body angular momentum in older adults indicate greater rotational imbalance in the frontal plane
• This was assessed during habitual walking and in response to walking balance perturbations

Older adults exhibited larger anterior-posterior margin of stability compared to younger adults during walking.

• Margin of stability was used as a whole-body balance metric during habitual walking
• Larger anterior-posterior margin of stability in older adults may reflect a more cautious gait strategy
• This finding was assessed as part of a broader set of whole-body balance metrics

Older adults showed larger perturbation-induced changes in whole-body angular momentum than younger adults.

• Two contexts of walking balance perturbations were used to assess reactive balance
• Greater perturbation-induced changes in whole-body angular momentum in older adults indicate reduced ability to resist destabilizing perturbations
• This finding highlights age-related deficits in reactive balance control during walking

Better foot-ankle leverage during habitual walking correlated with larger margins of stability and smaller ranges of whole-body angular momentum.

• This represents the first reported evidence of a correlation between foot-ankle mechanical leverage and whole-body balance metrics
• Better foot-ankle leverage was associated with more stable gait as indicated by larger margin of stability
• Better foot-ankle leverage was also associated with smaller ranges of whole-body angular momentum, indicating less rotational instability
• The correlations were assessed across interindividual differences in foot-ankle leverage during habitual walking

Walking speed affected foot-ankle mechanical leverage and balance metrics.

• The study quantified both age and walking speed effects on mechanical leverage of the foot and ankle
• Walking speed effects were assessed alongside age effects as a key independent variable
• Specific walking speed conditions were used to examine habitual and perturbed walking contexts