The Intramuscular Circulation Is Affected by Neck and Shoulder Pain

The purpose of this study was to investigate the effects of neck and shoulder pain (NSP) and the position of the head and neck on the intramuscular circulation of the cervical muscles such as the trapezius and levator scapulae muscles in young females. Ten NSP subjects (mean age: 20.9 ± 0.5 years) and ten non-NSP subjects (mean age: 20.6 ± 0.7 years) were recruited to this study. Near-infrared spectroscopy (NIRS) was used to non-invasively measure total haemoglobin (Total-Hb), oxygenated haemoglobin (Oxy-Hb), and deoxygenated haemoglobin (Deoxy-Hb) of the trapezius and levator scapulae muscles. The measurements of Total-Hb, Oxy-Hb, and Deoxy-Hb were taken in the neutral position, immediately after the maximally flexed (extended) position, and after 30 s in the maximally flexed (extended) position. In flexion, no significant main effect or interaction was observed with Total-Hb and Oxy-Hb. A significant interaction was observed with Deoxy-Hb (p < 0.01). There was no significant difference in the changes over time in the NSP group (p = 0.91). However, in the non-NSP group, a significant increase was noted at the neutral position to immediately after the maximally flexed position (p < 0.01) and at the end of maintaining the maximally flexed position (p < 0.01). In extension, no significant main effect or interaction was observed with Total-Hb and Oxy-Hb. A significant interaction was observed with Deoxy-Hb (p < 0.01). In the NSP group, no significant difference was observed in the changes over time (p = 0.91). In the non-NSP group, however, a significant decrease was observed from the neutral position to immediately after the maximally extended position (p < 0.01). The results of this study indicate that maintaining either maximal cervical flexion or extension may affect venous blood flow on non-NSP group. However, no effect on NSP group was observed due to existing diminished intramuscular circulation.