Gender difference and lifting technique under light load conditions: a principal component analysis

Abstract

The majority of lifting research uses male subjects, and thus it is necessary to investigate if gender differences exist in lifting technique that may limit extrapolation of these studies. Three-dimensional kinematics of the ankle, knee, hip and lumbar and thoracic spine were collected for 30 subjects (15 males and 15 females) during lifting trials under two load conditions: 0% and 10% of maximum isometric back strength. Applying a principal component analysis (PCA) to the lifting waveforms, 30 principal components (PCs) were retained using a 90% trace criterion. There was a significant effect of load on PC2 of lumbar spine flexion and PC2 of hip rotation, but no effect of gender on any of the PCs. Therefore, independent of gender, under loaded conditions individuals demonstrated a semi-squat lifting technique. By employing a sophisticated statistical method such as PCA and standardising load to the individual's strength characteristics, there was no significant effect of gender on lifting technique.

Keywords:

• lifting kinematics
• principal component analysis
• gender differences
• methods
• manual materials handling

Acknowledgements

This project was funded by the Natural Sciences and Engineering Research Council of Canada, Ontario Graduate Scholarship and a research grant provided by the Workplace Safety and Insurance Board (Ontario).