Examining movement asymmetries during three single leg tasks using interlimb and single subject approaches

Purpose: s:To examine whether healthy individuals displayed asymmetric trunk and lower extremity kinematics in the frontal and sagittal planes using both interlimb and single subject models. Methods:Trunk, pelvis, and lower extremity kinematic waveforms were analyzed bilaterally during the single leg squat (SLS), forward step down (FSD), and lateral step down (LSD). Participants identified task specific preferred and non-preferred legs based on perceived stability for interlimb analyses. Movement patterns were also analyzed with a single subject approach that included Fisher's exact tests to assess whether asymmetries were related to the task. Results:Participants were found to have increased pelvic drop on the non-preferred leg during the LSD from 41 to 77% of the movement (p = 0.01). No other bilateral differences were found for interlimb analyses. Single subject analyses indicated that no task had a greater probability of finding or not finding asymmetries. Associations were found between the FSD and SLS for frontal plane hip (p < 0.01) and knee motion (p < 0.01). Conclusions:Interlimb analyses can be influenced by intraparticipant movement variability between preferred and non-preferred legs. Movement asymmetries during single leg weightbearing are likely task dependent and a battery of tests is necessary for assessing bilateral differences.

Automated summary

The purpose of this study was to examine whether healthy individuals displayed asymmetric trunk and lower extremity kinematics in the frontal and sagittal planes. Both interlimb and single subject models were used for analysis. The results showed that participants had increased pelvic drop on the non-preferred leg during lateral step down. Other bilateral differences were not found for interlimb analyses. Single subject analyses indicated that asymmetries were task dependent, and there were associations between certain tasks in terms of hip and knee motion in the frontal plane.