Study on surface electromyography characteristics of erector spinae muscles at different spinal anteversion angles of the scrapers / 中华劳动卫生职业病杂志

Objective: To simulate and evaluate the scraping and grinding work of workers with different spinal anteversion angles, and to explore the effects of different anteversion angles on the erector spinae muscles of scrapers. Methods: In November 2019, 16 male college student volunteers were recruited to simulate workers' scraping and grinding work. The parameters were 25°, 15 times/min, 15°, 30 times/min, 5°, 60 times/min respectively. The surface electromyography (sEMG) was used to collect the electromyographic signals of the erector spinae muscles, and the surface electromyographic characteristics of the erector spinae muscles were evaluated with Borg Scale. Results: There were significant differences between the maximum voluntary contraction percentage (MVE%) of the left and right erector spinae muscles groups in the three groups with different spinal anteversion angles (F(left)=13.41, P(left)<0.001; F(right)=4.74, P(right)=0.005) , and the EMG amplitude was higher at 25°, 15 times/min. At 15°, 30 times/min, MVE% of the left side was significantly higher than that of the right side (t=2.58, P=0.021) . There was significant difference in the mean power frequency (MPF) of the right erector spinae muscle in the three groups (F=9.42, P<0.001) , but there was no significant difference in the MPF of the left erector spinae muscle (F=0.30, P=0.823) . The fitting line showed that the left erector spinae muscle showed a downward trend at 5°, 60 times/min (t=-5.39, P=0.012) . Conclusion: Scrapers are less likely to be fatigued when the posture is 15°, 30 times/min, but they are more likely to be fatigued when working at 5°, 60 times/min.

Relationship between the distribution of spinal nerve posterior ramus and locations of acupoint in low back / 中国针灸

<p><b>OBJECTIVE</b>To explore the relationship between the distributions of posterior ramus of spinal nerve (PRSN) and locations of acupoint in low back through anatomical observation.</p><p><b>METHODS</b>The regional anatomy was performed at five corpses to observe the distribution of erector spinae muscle and PRSN in areas ofpoints and back-points in low back.</p><p><b>RESULTS</b>The T, L, L, Land LPRSN distributed on both sides of the spine; the medial branches of PRSN travelled between spinalis thoracis muscle and longissimus thoracis muscle, while the lateral branches of PRSN travelled between longissimus thoracis muscle and iliocostalis lumborum muscle.</p><p><b>CONCLUSIONS</b> points and back-points in low back are closely associated with PRSN, particularly T, L, L, Land L.</p>

Surface electromyography signals from neck muscles during different craniocervical postures in a lateral recumbent position / 中华物理医学与康复杂志

Objective To survey cervical myoelectric signals during craniocervical flexion, neutral and extension postures, and to explore the evidence that proper head position can alleviate cervical muscle fatigue in a lateral recumbent position. Methods Surface electromyography (sEMG) signals were detected from the sternocleidomastoid, upper trapezius and erector spinae muscles of 30 young subjects bilaterally during craniocervical flexion,neutral and extension postures in the left lateral recumbent position. The integrated trace area (IEMG) and median frequency (MF) were estimated. Results The average IEMG of the sternocleidomastoid muscles was significantly lower in flexion than in extension bilaterally. The average IEMG of the erector spinae muscles was lower in extension than in flexion bilaterally, and the difference was again significant. The IEMGs of the upper trapezius muscle showed no significant difference on average in the three postures bilaterally. There was no significant MF difference in any of the muscles. Conclusions The muscles in the cervical back were less activated during craniocervical extension in a lateral recumbent position. A little cranicocervical extension is optimal while resting in a lateral recumbent position.