Implications of intra-limb variability on asymmetry analyses

Area of Science:

• Biomechanics
• Sports Science
• Human Movement Analysis

Background:

• Asymmetry quantification in sports often focuses on discrete kinematic and kinetic variables.
• Intra-limb variability has been underrepresented in previous asymmetry analyses.
• Understanding limb variability is essential for accurate performance and injury risk assessment.

Purpose of the Study:

• To investigate the impact of intra-limb variability on calculating lower-limb asymmetry during sprint running.
• To inform future analyses by highlighting the importance of including intra-limb variability.
• To determine if intra-limb variability affects the significance of observed asymmetries.

Main Methods:

• Collected synchronized lower-limb kinematic and kinetic data from eight trained athletes during maximal velocity sprinting.
• Quantified asymmetry using a modified symmetry angle for selected variables.
• Calculated significant differences (P < 0.05) between left and right limb values to assess intra-limb variability relative to between-limb differences.

Main Results:

• Significant asymmetry was found in only 39% of kinematic and 23% of kinetic variables.
• Large kinetic asymmetry values were observed in some athletes but were not statistically significant due to high intra-limb variability.
• Asymmetries that were significant varied between individual athletes.

Conclusions:

• Excluding intra-limb variability can lead to misleading conclusions in asymmetry analyses.
• Intra-limb variability significantly influences the interpretation of kinematic and kinetic asymmetry.
• Future running gait analyses should incorporate intra-limb variability for more accurate assessments and to avoid reporting non-significant asymmetries.