Validity of self-reporting and video-recording for measuring knee-straining work postures

Area of Science:

• Occupational Health
• Ergonomics
• Biomechanics

Background:

• Knee-straining work postures are prevalent in trades like carpentry and floorlaying.
• Accurate measurement of exposure duration is crucial for understanding occupational knee disorders.
• Existing methods for quantifying work posture duration have limitations.

Purpose of the Study:

• To compare the validity of self-reporting versus video-recording for measuring knee-straining work posture duration.
• To assess the reproducibility of video-recording timings for knee-straining work.
• To evaluate the association between observed and self-reported knee-straining work.

Main Methods:

• Thirty-nine carpenters and 33 floorlayers were video-recorded during work.
• Participants immediately self-reported time spent in knee-straining postures.
• Investigators measured knee-straining posture duration using video playback and stopwatch.
• Reproducibility was assessed by two investigators measuring the same video recordings.

Main Results:

• Video-observation was highly effective for timing knee-strain work.
• A strong correlation (Spearman's rho = 0.88) was found between observed and self-reported knee-straining work.
• Self-reported durations showed good correlation with video-recorded measurements.
• High agreement was observed between two investigators timing knee-straining work from video recordings.

Conclusions:

• Video-recording is a valid and reproducible method for measuring the duration of knee-straining work postures.
• Self-reporting demonstrates good validity when compared to objective video measures.
• The findings support the use of video-based methods in occupational studies of knee exposure.