Does kinematic coupling in the lower extremities and trunk during a chair transfer task change between younger and...

Past work examining relationships across biomechanical domains during gait has observed that age-related effects may be dependent on the joint of interest. This work has not been extended to other functional tasks, nor to relationships within the kinematic domain.

How does kinematic coupling between the lower extremity and trunk segments during a functional task (sit-stand-sit) differ between younger and older adults?

Younger (n = 21) and older (n = 28) adults performed a sit-stand-sit task while whole-body motion was tracked. Sagittal foot, shank, thigh, and trunk segment angles were calculated and cross-correlated between pairings of adjacent segments (foot-shank, shank-thigh, and thigh-trunk). Maximum cross-correlation coefficients and their temporal lags quantified the strength and timing of coupling, respectively, and were compared between age groups.

Where significant differences were identified, foot-shank and thigh-trunk cross-correlation coefficients were generally stronger, and temporal lags were generally shorter, for older and younger adults, respectively. The thigh-trunk pairing exhibited the opposite trend during the sit-down phase, with stronger cross-correlation coefficients observed for older adults.

These joint-dependent trends may be an indicator of the use of compensatory strategies during sit-stand-sit, which may aid in identifying older adults who could benefit from interventions to prevent functional declines in the ability to perform chair transfer tasks.