White Paper – Posture Risk Identifying Problematic Overhead Work Postures with Body-Worn Sensors

by Jessica Zendler

A guide to the Ergo Senz Posture risk module for health and safety professionals.


Work injuries in the United States led to $171 billion in direct and indirect costs and 105 million lost work days in 2019 alone. Work-related musculoskeletal disorders (WMSDs) account for up to 60% of Canadian workers’ compensation claims. WMSDs of the upper extremity are common and have been linked to prolonged repetitive overhead work. Early identification of problematic overhead arm postures can reduce these disruptive and costly injuries. This white paper discusses the benefits of sensor-based assessment of awkward work postures and presents the technical basis for the ErgoSenz Posture risk module.

Assessment is Critical for Preventing WMSDs

Programmatic assessment of risk factors for WMSDs, coupled with targeted mitigation efforts, is an effective method for reducing workplace injuries and associated costs. Localized fatigue, caused by the combination of awkward postures, frequent repetition, limited rest, and sustained duration of effort, is believed to precipitate these costly injuries. The American Conference of Governmental Industrial Hygienists (ACGIH) has established a Threshold Limit Value (TLV) for assessing upper-limb localized fatigue. The TLV calculates a maximum acceptable effort (load) based on the duty cycle of the effort (Figure 1). As the duty cycle increases fatigue begins at lower effort levels. Implementing the ACGIH Upper Limb Localized Fatigue TLV is operationally challenging, but recent advancements in body-worn sensors have opened the opportunity for efficient, systematic application of the TLV to assessing repetitive overhead work.