Shoulder injuries are among the most common musculoskeletal disorders affecting industrial workers, with the most predominant type being a rotator cuff tear. The rotator cuff consists of four muscles that surround the shoulder joint to keep the bones in place during movement. The most common cause of this injury is working with the hands over shoulder height (Blache et al., 2014).
Strenuous tasks that involve applying heavy loads to the shoulder, such as lifting and carrying, combined with frequent and prolonged tasks that require the hands to work above shoulder height, put the worker at an even greater risk.
Why does the risk increase? Performing a forceful task while in an awkward posture requires high contraction forces by the muscles. Based on research, operators experience pain and fatigue when lifting 10 kilograms or more above the shoulder level for 15 minutes or longer (Beach, Senthilselvan & Cherry et al., 2012). This means that constant excessive or prolonged exposure to forceful exertions can result in muscle strain, damage, or soreness. Moreover, surrounding structures near the rotator cuff (nerves) can be pinched or become inflamed when performing these kinds of tasks.
While shoulder injuries are common, they are easily preventable. Employers should conduct regular task evaluations or consult with an ergonomist on varying issues. When hazards or areas of concern arise, they should be quickly corrected through engineering improvements. Ensuring that workers can complete all tasks at proper hand working heights and reducing the weight of objects they must support, lift, or carry, will decrease the injury risk and create a safer and more comfortable environment for all.
References: Beach, J., Senthilselvan, A., Cherry, N. (2012). Factors affecting work-related shoulder pain, Occupational Medicine, 61(6),451-454. Blache, Y., Desmoulins, L., Allard, P., Plamondon, A., Begon, M. (2014). Effects of height and load weight on shoulder muscle work during overhead lifting task. Ergonomics, 58(5), 1-14. Nové-Josserand, L., Liotard, J.-P., Godeneche, A., Neyton, L., Borel, F., Rey, B., Noel, E., Walch, G. (2011). Occupational outcome after surgery in patients with a rotator cuff tear due to a work-related injury or occupational disease. Orthopaedics & Traumatology: Surgery & Research, 97(4), 361-366.