Study of Physical Discomfort and Working Postures Related to Squatting/Kneeling Tasks Performed on Construction Sites

A cross-sectional survey of 599 male and female workers at construction sites in Taiwan was carried out via questionnaire. Information was obtained on individual factors, job characteristics, workloads, and physical discomfort. Observational data was then collected for 23 construction workers performing six activities to obtain 1,436 observations using Ovako working posture analysis system (OWAS), to identify and evaluate harmful working postures in the construction workplace. The observational results showed that the most pronounced and prevalent complaints after prolonged squatting or kneeling relate to the knee (54.6%), upper back (53.8%), and lower back (53.3%). Female workers had higher prevalence of physical discomfort than male workers for most body areas. Multivariate logistic regression models were used to predict physical discomfort. Daily squatting or kneeling on a construction site for more than 4 hours was strongly associated with discomfort in the upper and lower extremities (odds ratio ranges from 1.74 to 2.56). Among the six job activities analyzed in this investigation, from OWAS, electrical work (50%), tile work (48%) and retaining pile work (42%) were the major contributors to poor working postures for construction workers. The results of this study can be employed to construct a workplace squatting/kneeling task design reference to improve musculoskeletal fatigue and prevent the development of relevant disorders.