Older adults had lower CoM speed, altered CoM acceleration, and greater ankle multi-muscle coactivation than younger adults, potentially due to adoption of cautious gait, with limb-specific, temporal associations between coactivation and CoM kinematics.
Key Findings
Results
Older adults demonstrated higher right ankle multi-muscle coactivation than young adults at multiple specific gait cycle intervals.
During the right stride, older adults had higher right ankle coactivation at 14.7%–17.2% and 30.3%–33.65% of the gait cycle.
During the left stride, higher right ankle coactivation occurred at 65.7%–68.1% and 80%–82.6% of the gait cycle.
Coactivation was calculated using a time-varying multi-muscle coactivation function.
Statistical parametric mapping t-tests were used to identify group differences across the full time-series.
Results
Older adults exhibited lower center of mass (CoM) speed than young adults across multiple intervals of both right and left strides.
During the right stride, lower CoM speed in older adults occurred at 0.01%–9.1%, 44.7%–61.1%, and 94.6%–100% of the gait cycle.
During the left stride, lower CoM speed occurred at 0.01%–10.7%, 45.8%–68.7%, and 93.7%–100% of the gait cycle.
CoM speed was calculated with three-point finite difference formulae.
Differences were identified using statistical parametric mapping t-tests.
Results
Older adults showed lower CoM deceleration than younger adults at specific intervals during both right and left strides.
During the right stride, lower deceleration in older adults occurred at 19.2%–21.4% and 68.1%–72.4% of the gait cycle.
During the left stride, lower deceleration occurred at 17.7%–22.4% and 68.6%–72.4% of the gait cycle.
Reduced deceleration may reflect alterations in braking mechanics associated with cautious gait in older adults.
Results
Older adults exhibited lower CoM acceleration than younger adults at specific gait cycle intervals.
During the right stride, lower acceleration in older adults occurred at 45.1%–49.2% of the gait cycle.
During the left stride, lower acceleration occurred at 99%–100% of the gait cycle.
Altered acceleration patterns may reflect reduced propulsive capacity in older adults.
Results
Pointwise regression analysis revealed limb-specific, temporal associations between knee coactivation and CoM speed.
For the right limb, knee coactivation was associated with CoM speed at 62.7%–63% and 84.7%–92.1% of the gait cycle.
For the left limb, knee coactivation was associated with CoM speed at 62.4%–64% and 85.8%–91.3% of the gait cycle.
A pointwise regression analysis with false discovery rate correction was used to assess associations.
The analysis was performed for the ipsilateral leg during its respective stride to account for effects of time-shifting on results.
Results
Ankle coactivation showed limb-specific associations with CoM speed at distinct gait cycle intervals.
Right ankle coactivation was associated with CoM speed at 0.01%–0.6% of the right stride.
Left ankle coactivation was associated with CoM speed at 54.6%–64.1% of the left stride.
The limb-specific nature of these associations suggests different functional roles of ankle musculature in each limb during gait.
Results
Both knee and ankle coactivation showed limb-specific, temporal associations with CoM acceleration.
Knee coactivation was associated with CoM acceleration at 58.2%–58.7% (right stride) and 79.4%–80.9% (left stride).
Ankle coactivation was associated with CoM acceleration at 60.5%–64.2% (right stride) and 93.9%–94.2% (left stride).
These temporal associations were interpreted as possibly reflecting demands at gait phases such as ground clearance, propulsion, and stabilization.
Methods
The use of statistical parametric mapping and pointwise regression with false discovery rate correction enabled time-series-level analysis of coactivation and CoM kinematics associations.
Prior research had assessed aging effects on coactivation and CoM kinematics using phase-based (scalar) analyses; scalar time-series analysis was previously unexplored.
Statistical parametric mapping t-tests were applied to identify between-group differences across the full gait cycle time-series.
False discovery rate correction was applied to the pointwise regression to control for multiple comparisons across time points.
The ipsilateral leg was analyzed during its respective stride to avoid artifacts from time-shifting.
What This Means
This research suggests that older adults walk differently from younger adults in several measurable ways throughout the entire gait cycle, not just at specific phases. Using advanced time-series statistical methods, the study found that older adults consistently moved their center of mass (the body's overall balance point) more slowly and with less acceleration and deceleration than younger adults. At the same time, older adults showed higher activation of muscles around the ankle working together (coactivation), which may reflect a more cautious, stiffened walking strategy to maintain stability.
The study also found that muscle coactivation around the knee and ankle is statistically linked to how fast and how smoothly the body's center of mass moves, but these links appear at different specific moments in the gait cycle and differ between the right and left legs. This suggests that each limb plays a distinct role at different moments—such as pushing off the ground, clearing the foot, or stabilizing the body—and that muscle coordination strategies are finely tuned to these varying demands throughout each step.
This research matters because it provides a more detailed, moment-by-moment picture of how aging changes walking mechanics compared to traditional summary measures. Understanding exactly when and where older adults show altered muscle coordination and movement efficiency could help in designing more targeted rehabilitation programs or fall-prevention interventions, and highlights the importance of analyzing both sides of the body separately when studying gait.
Alighanbari M, Champion R, Hoang K. (2026). Time-series analysis of multi-muscle coactivation and center of mass kinematics in older adults during gait.. Medical engineering & physics. https://doi.org/10.1088/1873-4030/ae9f5e