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

Area of Science:

• Biomechanics
• Human Movement Analysis

Background:

• Assessing bilateral kinematic differences in healthy individuals is important for understanding movement patterns.
• Previous studies have explored asymmetries, but the influence of preferred vs. non-preferred limbs and task specificity requires further investigation.

Purpose of the Study:

• To investigate trunk and lower extremity kinematic asymmetries in healthy individuals during functional tasks.
• To compare interlimb and single-subject analysis models for detecting movement asymmetries.
• To determine if asymmetries are task-specific.

Main Methods:

• Kinematic data of the trunk, pelvis, and lower extremities were collected bilaterally during single leg squat, forward step down, and lateral step down tasks.
• Participants designated preferred and non-preferred legs for interlimb comparisons.
• Single-subject analyses, including Fisher's exact tests, were used to evaluate task-related asymmetries.

Main Results:

• Increased pelvic drop was observed on the non-preferred leg during the lateral step down task (p=0.01).
• No other significant bilateral differences were detected using interlimb analyses.
• Single-subject analyses did not reveal a higher probability of asymmetries for any specific task.
• Associations between forward step down and single leg squat tasks were found for frontal plane hip and knee motion (p<0.01).

Conclusions:

• Interlimb analysis of movement asymmetries can be affected by within-participant variability between preferred and non-preferred limbs.
• Movement asymmetries during single-leg weightbearing activities appear to be task-dependent.
• A comprehensive battery of tests is recommended for accurately assessing bilateral kinematic differences.