Identification of Biomechanical Risk Factors for the Development of Lower-Back Disorders during Manual Rebar Tying

Abstract

High prevalence of musculoskeletal disorders among construction workers pose challenges to the productivity and occupational health of the construction industry. To mitigate the risk of musculoskeletal disorders, construction managers need to deepen their understanding of the physical and biomechanical demands of various construction tasks so that appropriate policies and preventive measures can be implemented. Among various construction trades, rebar workers are highly susceptible to lower-back disorders (LBDs) given the physically demanding nature of their work tasks. In particular, rebar tying is considered to be closely related to LBDs because it exposes workers to multiple ergonomic risk factors (repetitive works in prolonged static and awkward postures). The objective of the current study was to compare the differences in lumbar biomechanics during three typical rebar tying postures: stooping, one-legged kneeling, and squatting. Biomechanical variables including trunk muscle activity and trunk kinematics were measured by surface electromyography and motion sensors, respectively. Ten healthy male participants performed a simulated rebar tying task in each of the three postures in a laboratory setting. Repeated measures analysis of variance showed that while each posture has its unique trunk kinematic characteristics, all these postures involved excessive trunk inclination that exceeded the internationally recommended trunk inclination angle of 60°for static working postures. Of the three postures, stooping posture demonstrated a significant reduction in electromyographic activity of lumbar muscles (a reduction in 60-80% of muscle activity as compared to the other two postures). The reduced muscle activity may shift the loading to passive spinal structures (e.g., spinal ligaments and joint capsules), which is known to be a risk factor for LBD development. Collectively, the results from this study may help explain the high prevalence of LBDs in rebar workers. Future studies are warranted to confirm the findings at construction sites and to develop appropriate ergonomic approaches for rebar workers.dividual papers. This paper is part of the Journal of Construction Engineering and Management, © ASCE, ISSN 0733-9364. © ASCE 04016080-1 J. Constr. Eng. Manage. J. Constr. Eng. Manage., 04016080 Downloaded from ascelibrary.org by Arizona State Univ on 07/26/16. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04016080-2 J. Constr. Eng. Manage. J. Constr. Eng. Manage., 04016080 Downloaded from ascelibrary.org by Arizona State Univ on 07/26/16. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04016080-10 J. Constr. Eng. Manage. J. Constr. Eng. Manage., 04016080 Downloaded from ascelibrary.org by Arizona State Univ on 07/26/16.

The impact of tool selection on back and wrist injury risk in tying steel reinforcement bars: a single case experiment

“…This has been confirmed in laboratory-based simulations studies. For example , Umer, et al (2017) used wearable sensors to directly measure biomechanical risk factors associated with a simulated steel fixing task, finding lumbar flexion angles substantially exceed recommended limits (Umer, et al, 2017). However, field-based studies also show that ergonomic exposures vary significantly depending upon the specific work context.…”

“…Lightweight wearable sensors are capable of providing large quantities of highly accurate data on a range of MSD risk exposure variables (Inyang, et al, 2012). To date, whole body measurement systems have been used in a laboratory context (Umer, et al (2017), however, it is less common for such systems to be used in construction work settings.…”

Measuring Biomechanical Risk in Lifting Load Tasks Through Wearable System and Machine-Learning Approach

“…Manual material handing (MMH) tasks expose workers to a high level of ergonomic hazards, which finds high correlation with the onset of work-related musculoskeletal disorders (WMSDs) [7][8][9][10][11]. Awkward postures have been identified as risk factors for the musculoskeletal system, especially in the construction field [12][13][14][15]. Though different guidelines have been designed for risk assessments, they have not always been definitive due to factors such as high variability, repetitiveness, and a low standardization of tasks [16][17][18][19][20][21][22].…”

Motion-based analysis for construction workers using biomechanical methods

“…However, the subjective assessment based on observation is time-and labor-consuming with low repeatability among different observers (Takala et al, 2010). With the development of sensor technology, Inertial Measurement Units (IMU) have been used to solve the above problem (Yan et al, 2017;Umer et al, 2017). IMU measures the relative rotation angles of joints, and human body postures can be computed based on these joint parameters.…”

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