Characteristics of Surface Electromyograph Activity of Cervical Extensors and Flexors in Nonspecific Neck Pain Patients: A Cross-Sectional Study.

Background and Objectives: We identified typical surface electromyogram (sEMG) activities of the cervical extensors and flexors during motions in the three anatomical planes in healthy adults. The aim of this study was to explore characteristics of sEMG activities of these cervical muscles in nonspecific neck pain (NSNP) patients based on healthy adults. Materials and Methods: Participants were 24 NSNP patients (NSNP group, mean ± SD of age, 47.5 ± 15.5) and 24 healthy adults (control group, 20.5 ± 1.4). For each participant, sEMG of the cervical extensors and flexors was recorded during neck flexion, extension, bilateral lateral flexion, bilateral rotation, and at the neutral position in Phase I (the neck from the neutral position to the maximum range of motion), Phase II (at the maximum range of motion), and Phase III (from the maximum range of motion to the neutral position), yielding a total of 42 phases. A percentage of maximum voluntary contraction to normalize muscle activity in each phase was calculated to obtain the ratio of muscle activities in the extensors and flexors in each of 36 phases of the motions to the neutral position and ratio of the flexors to extensors in activity for 21 phases. Results: In 28 of 36 phases of the motions, the ratios of muscle activities in the extensors and flexors to the neutral position in the NSNP group were significantly larger than the control group (p < 0.05). In 6 of 21 phases, the ratios of the flexors to extensors in activity in the NSNP group were significantly larger than in the control group (p < 0.05). Conclusions: In NSNP patients, the activity of the cervical extensors and flexors associated with neck motion increased with an imbalance in activity between these muscles compared to their activity in healthy adults. The results of this study will be useful in understanding the pathogenesis of NSNP and in constructing an objective evaluation of the treatment efficacy on NSNP patients.

The Mode of Activity of Cervical Extensors and Flexors in Healthy Adults: A Cross-Sectional Study.

Background and Objectives: The purpose of this study was to investigate the activity of bilateral cervical extensors and flexors on the sagittal, frontal, and horizontal planes of healthy adults during motions of the neck in a sitting position, which has not been satisfactorily investigated by surface electromyogram (sEMG). Materialand Methods: We recruited 35 healthy participants (mean ± standard deviation of age, 20.3 ± 2.4). sEMG recordings of the cervical extensors and flexors were performed for a total of nine seconds in three phases: Phase I involved the motion of the neck from the neutral position to the maximum range of motion; Phase II involved maintaining the neck at the maximum range of motion; and Phase III involved the motion of the neck from the maximum range of motion to the neutral position during neck flexion, extension, right and left lateral flexion, right and left rotation, and maintaining the neck in the neutral position. Muscle activities in each motion were normalized as a percentage of maximal voluntary contraction (%MVC) so that the muscles could be compared. Results: The %MVC of the extensors was significantly larger than that of the flexors in the neutral position (p < 0.001). In addition, the %MVCs of the following were significantly larger than the %MVC in the neutral position: the extensors in flexion (p = 0.014) and extension (p = 0.020), the ipsilateral extensors (p = 0.006) and flexors (p < 0.001) in lateral flexion in Phase I; the flexors in flexion (p < 0.001), the extensors in extension (p = 0.010), and the ipsilateral extensors and flexors in lateral flexion (p < 0.001) in Phase II; the extensors and flexors in flexion (p < 0.001), the flexors in extension (p < 0.001), the ipsilateral flexors (p < 0.001), the contralateral flexors (p = 0.004) and the contralateral extensors (p = 0.018) in lateral flexion in Phase III; and the bilateral extensors and contralateral flexors during rotation in all three phases (p < 0.001). Conclusion: The typical sEMG activities of the extensors and flexors during motion of the neck in healthy adults were identified in this study; this information can be used to understand the pathophysiology of non-specific neck pain and to provide an index for evaluating the effect of treatment.

Effects on Acupuncturist Blinding: Different Diameters of Double-blind Acupuncture Needles.

CONTEXT: It's difficult to conduct experiments using a double-blind design in controlled clinical trials of acupuncture. To resolve this problem with blinding, we designed double-blind needles (DBNs) with stuffing to mimic the resistance felt during insertion of a regular acupuncture needle. Results of the past studies using 0.16 mm diameter DBNs found that the resistance felt by the acupuncturists during insertion successfully blinded them. OBJECTIVE: The study intended to compare the effects on an acupuncturist's blinding when the practitioner used penetrating DBNs with 0.14, 0.16, 0.18, and 0.20 mm diameters. DESIGN: We conducted a double-blind randomized trial. SETTING: The study took place at the Japan School of Acupuncture, Moxibustion. and Physiotherapy in Tokyo, Japan. PARTICIPANTS: The participant was one licensed acupuncturist who performed 320 needle insertions during acupuncture for 20 healthy students, who were familiar with acupuncture and who attended the Japan School of Acupuncture, Moxibustion, and Physiotherapy. METHODS: The acupuncturist was informed she would administer a penetrating or non-penetrating needle; however, only penetrating needles were used. She inserted the four sizes of needles in both of each student's dorsal forearms using an alternating twirling technique. This procedure was repeated once more on another day, with at least one day between sessions. PRIMARY OUTCOME MEASURES: After the acupuncturist removed each needle, we asked her to guess: (1) the type of needle inserted, (2) her level of confidence in the guess, and (3) the clues that contributed to her guess. A chi-squared test was used to determine whether the ratio of correctly or incorrectly identified needles met an expected probability of 0.5 for each needle diameter. RESULTS: Of the 320 needle insertions, the acupuncturist correctly identified 54% of 0.14 mm, 45% of 0.16 mm, 46% of 0.18 mm, and 50% of 0.20 mm needle insertions. The correct and incorrect ratios of identified needles were fitted with a probability of 0.5, with no significant differences in the acupuncturist's confidence (P = .16). In 99% of the tests, the cue that contributed to the acupuncturist's guess was the feeling of the needle insertion. CONCLUSION: These findings indicate that the differences in the diameters of DBNs from 0.14 to 0.20 mm didn't significantly affect the acupuncturist's blinding.