Abstract: BACKGROUND: The incidence rate of chronic non-specific neck pain is high and the etiology is unknown. Myofascial pain and deep cervical flexor atrophy are the key factors. Extracorporeal shockwave therapy can improve microcirculation, relieve local pain, and delay the degenerative development of the cervical spine, while motion control training can significantly improve neck muscle strength and endurance and reduce neck pain. However, both methods have limited effectiveness when applied individually.
OBJECTIVE: To explore the therapeutic efficacy of extracorporeal shock wave intervention combined with motion control training at the upper trapezius muscle on chronic non-specific neck pain. 
METHODS: Forty-two patients with chronic non-specific neck pain recruited from Shenyang Sport University were randomly divided into three groups: a shock wave group (n=14), in which extracorporeal shockwave intervention at the upper trapezius muscle was given for 10-15 minutes, once a week for 4 weeks; a training group (n=14), in which motion control training was given for 40-50 minutes, three times a week for 4 weeks; and a combination group (n=14), in which extracorporeal shockwave intervention at the upper trapezius muscle combined with motion control training was performed for 4 weeks. Patients were assessed for pain intensity, cervical spine function, upper trapezius muscle thickness, hemodynamic parameters, and serum interleukin 6 and tumor necrosis factor α levels before intervention, 1 week and 4 weeks after intervention. 
RESULTS AND CONCLUSION: (1) Compared with the pre-intervention period, the visual analogue scale scores and neck disability index in the three groups were lower after 1 and 4 weeks of intervention (P < 0.05), and the visual analogue scale scores and neck disability index in the combination group were lower than those of the shock wave group and the training group (P < 0.05). (2) Compared with the pre-intervention period, the upper trapezius thickness increased in the training group and the combination group after 4 weeks of intervention (P < 0.05); the upper trapezius thickness was greater in the combination group than in the shock wave group and the training group after 4 weeks of intervention (P < 0.05). (3) The shock wave group and the combination group had an increase in the peak systolic velocity of the ascending segment of the transverse carotid artery (P < 0.05) and a decrease in the resistance index (P < 0.05) after 1 and 4 weeks of intervention, while the training group showed an increase in the peak systolic velocity of the ascending segment of the transverse carotid artery 
(P < 0.05) and a decrease in the resistance index (P < 0.05) after 4 weeks of intervention. The peak systolic velocity of the ascending segment of the transverse carotid artery in the combination group was higher (P < 0.05) and the resistance index was lower (P < 0.05) than those in the shockwave group and the training group after 1 and 4 weeks of intervention. (4) Compared with the pre-intervention period, the levels of interleukin 6 and tumor necrosis factor α were reduced in the shock wave and combination groups after 1 and 4 weeks of intervention (P < 0.05), and in the training group after 4 weeks of intervention (P < 0.05). After 1 and 4 weeks of intervention, the levels of interleukin 6 and tumor necrosis factor α were lower in the combination group than in the shock wave group and the training group (P < 0.05). To conclude, extracorporeal shock wave combined with motion control training for chronic non-specific neck pain significantly reduces pain and improves neck function, and the mechanism of action may be to promote the blood flow velocity at the trigger point, reduce blood flow resistance, reduce the serum levels of interleukin 6 and tumor necrosis factor α, and increase the thickness of the upper trapezius muscle.

Key words: neck pain, upper trapezius muscle, extracorporeal shock wave, motion control, trigger point, inflammation, transverse carotid artery, engineered tissue construction