Changes in pressure pain in the upper trapezius muscle, cervical range of motion, and the cervical flexion-relaxation ratio after overhead work.

This study examined the changes in pressure pain in the upper trapezius muscle, cervical range of motion, and cervical flexion-relaxation ratio after overhead work. 14 workers were recruited. Pressure pain in the upper trapezius muscle, active cervical range of motion, and cervical flexion-relaxation ratio were measured in all subjects once before and once after overhead work. The pressure-pain threshold of the left upper trapezius muscle was 8.6 ± 2.5 lb before overhead work and 7.3 ± 2.4 lb after overhead work; that of the right upper trapezius muscle was 8.8 ± 2.9 and 7.3 ± 2.8 lb, respectively, revealing a significant decrease in pressure-pain threshold with overhead work. All cervical range of motion measures decreased significantly with overhead work. The cervical flexion-relaxation ratio on the left side was 1.3 ± 0.2 before overhead work and 1.1 ± 0.2 after overhead work; the respective values for the right side were 1.4 ± 0.5 and 1.2 ± 0.3 before and after overhead work, revealing a significant decrease with overhead work. We postulate that overhead work can reduce the pressure-pain threshold in the upper trapezius muscle and cause changes in the cervical range of motion and cervical flexion-relaxation ratio.