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Understanding the Physical Risk Factors Affecting Cervical Musculoskeletal Disorders

In spite of strong epidemiological evidence associating neck or cervical spine disorders with forceful arm exertions common at workplaces, effect of such exertions as causative of neck musculoskeletal disorders (MSD) is currently not well understood. In this study the effect of isometric lifting tasks at elbow, shoulder and overhead heights on the activities of two major neck muscles, sternocleidomastoid (anterior neck muscle) and upper trapezius (posterior neck muscle), was evaluated by using electromyography (EMG). Thirty healthy participants performed isometric lifting tasks exerting 25%, 50% and 75% of their respective maximum strengths at neutral and extended neck postures. Activities of sternocleidomastoid and upper trapezius increased with the increase in the lifting weights and heights. Extended neck posture caused a higher load on the neck musculature than the neutral posture. In conclusion, this study demonstrates a positive load-response relationship between forceful arm exertions and activation of the neck muscles.