Analysis of comfort and ergonomics for clinical work environments

Work related musculoskeletal disorders (WMSD) are a serious risk to workers' health in any work environment, and especially in clinical work places. These disorders are typically the result of prolonged exposure to non-ergonomic postures and the resulting discomfort in the workplace. Thus a continuous assessment of comfort and ergonomics is necessary. There are different techniques available to make such assessments, such as self-reports on perceived discomfort and observational scoring models based on the posture's relevant joint angles. These methods are popular in medical and industrial environments alike. However, there are uncertainties with regards to objectivity of these methods and whether they provide a full picture. This paper reports on a study about these methods and how they correlate with the activity of muscles involved in the task at hand. A wearable 4-channel electromyography (EMG) and joint angle estimation device with wireless transmission was made specifically for this study to allow continuous, long-term and real-time measurements and recording of activities. N=10 participants took part in an experiment involving a buzz-wire test at 3 different levels, with their muscle activity (EMG), joint angle scores (Rapid Upper Limb Assessment - RULA), self-reports of perceived discomfort (Borg scale) and performance score on the buzz-wire being recorded and compared. Results show that the Borg scale is not responsive to smaller changes in discomfort whereas RULA and EMG can be used to detect more detailed changes in discomfort, effort and ergonomics.