Effects of Industrial Maintenance Task Complexity on Neck and Shoulder Muscle Activity During Augmented Reality Interactions

Extensive studies have demonstrated the advantages of augmented reality (AR) in improving efficiency, thereby fulfilling a quality role in industry. Yet, the corresponding physical strain on individuals poses a significant challenge. This study explores the effects of task difficulty (complex versus simple maintenance activities) and multimedia guidance (e.g., paper-based versus AR via HoloLens) on physical strain, body discomfort ratings, perceived exertion, and mental effort. A 2 x 2 mixed design was employed, involving a total of 28 participants with an average age of 32.12 +/- 2.45 years. Physical strain was evaluated by measuring the normalized root mean square (RMS) of electromyography (EMG) indicators, expressed as a percentage of maximum voluntary contraction (%MVC) from six muscles (i.e., right flexor carpi radialis (RFCR), right middle deltoid (RMD), right upper trapezius (RUT), right cervical extensor (RCE), and right and left splenius (RSPL and LSPL) muscles. The results indicated that AR instruction, particularly in complex tasks, led to higher physical strain in the neck and shoulder muscles (RCE and RUT) compared with paper-based methods. However, AR significantly reduced strain in the RSPL, LSPL, RMD, and RFCR muscles during both simple and complex tasks. This study highlights that while AR can lower physical strain in certain muscle groups, it also introduces increased strain in the neck and shoulders, particularly during more demanding tasks. This study highlights the need for ergonomic considerations when designing and implementing AR technologies, especially for complex tasks that inherently demand more from the user, both physically and cognitively.