The knee adduction moment (KAM) is commonly used as a surrogate measure of medial compartment loading in individuals with medial knee osteoarthritis. This study investigated the effects of four gait modification strategies—toe-in, toeout, trunk lean, and knee thrust—on KAM peak and impulse using a within-subject design. Fourteen healthy adults performed normal walking and each modified gait condition. All gait modifications significantly reduced KAM peak compared to normal gait (p<0.05). However, a significant reduction in KAM impulse was observed only during the toe-out gait (p<0.01). Multiple regression analysis revealed that the moment arm accounted for 89–92% of the variance in KAM peak, while the combined effects of moment arm and stance time explained 87% of the variance in KAM impulse (p<0.001). The decrease in impulse during toe-out gait was primarily driven by a lower KAM peak without a significant increase in stance time. In contrast, for the other gait modifications, reductions in KAM peak were counterbalanced by prolonged stance time, resulting in no overall reduction in impulse. These findings suggest that both KAM peak and impulse should be considered when selecting gait modification strategies, with toe-out gait appearing to offer the most favorable biomechanical response in healthy adults.
This study aimed to determine mechanisms involved in the decrease of knee adduction moment (KAM) when waking with a contralateral cane without any constraint. Ten young subjects performed walking under two conditions: unassisted (no cane) or with a cane. After collecting data from the stance phase of the left foot, kinematic and kinetic data at early and late peaks of KAM were extracted for further analyses. When using a cane, early and late peaks of KAM decreased (p < 0.05) by 20.5% and 29.6%, respectively. Stepwise multiple regression analysis showed that the moment arm accounted for 59% and 95% of the variance of early and late KAM peaks, respectively. This reduction in moment arm occurred primarily due to lateral rotation of the GRF. Regarding the mechanism behind this, it could be due to the following: 1) by using a cane, the synthetic center of pressure shifted medially, which caused synthetic GRF to become more vertical than that of an unassisted walking and accordingly, and 2) the decrease of horizontal component of synthetic GRF reduced horizontal component of foot GRF, leading to lateral rotation of foot GRF. Understanding these mechanisms might help us improve effective use of canes.
In the rehabilitation of upper limb function impaired by stroke, facilitating the coordinated activation of multiple muscles is desirable. This study aims to analyze the coordination patterns of the tonic and phasic components of EMG during a reaching task and to investigate how the phasic component changes in relation to reaching speed. The analysis focused on the shoulder and elbow joints. EMG was recorded at five different speeds, with the slowest speed selected to represent the tonic component. The tonic component was then removed from the total EMG at the other four speeds to extract the phasic component. Correlation coefficients were calculated between the tonic component and joint angles, as well as between the phasic component and joint angular accelerations. For the tonic component, as joint angle increased during reaching, muscle activation also increased to counteract gravitational moments and enhance joint stiffness. For the phasic component, as reaching speed increased, the correlation between acceleration-deceleration patterns and muscle activation also increased. This suggests a greater synergistic contraction for enhanced acceleration and deceleration, as well as increased antagonistic contraction to ensure dynamic stability during faster movements
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