Neck disorders among construction workers: understanding the physical loads on the cervical spine during static lifting tasks.

In this study a common yet very strenuous construction work activity, was evaluated biomechanically by studying electromyography (EMG) of the major neck muscles. The muscles studied were the sternocleidomastoid and the upper trapezius. Fifteen healthy participants (10 males and 5 females) with no history of musculoskeletal abnormalities participated in this study. The participants lifted 25%, 50%, and 75% of their maximum shoulder height static strength at neutral, maximally flexed, and maximally extended neck postures. The weight lifted as well as the neck posture significantly affected the activities of the neck muscles. Increase in the weight increased the activation of the neck muscles. The sternocleidomastoid muscle was most active at the extended neck posture, while the upper trapezius muscle was most active at the flexed neck posture. The results of this study indicate that the neck muscles play an active role during lifting and holding tasks at shoulder height. Thus, such tasks could be probable risk factors associated with neck disorders prevalent among construction workers.