模拟长航时飞行对骨盆周围肌肉肌电活动和下背部主观疼痛等级的影响

Effect of Long-time Simulated Flight on EMG of Pelvic Relevant Muscles and Subjective Pain Level of Low Back

目的研究模拟长航时飞行对受试者骨盆周围肌肉肌电活动和下背部主观疼痛等级的影响,探讨肌肉功能失衡是否为引起下背痛的原因,为改善相关肌肉功能预防和治疗长航时飞行引发的下背痛问题提供理论依据。方法16名男性受试者分为2组,对照组8人,未经历过下背痛;背痛组8人,有或曾经有过3个月以上下背痛史。受试者完成4 h模拟长航时飞行前后,进行骨盆周围肌肉表面肌电测量,取30 s自然放松静止站立过程中相对稳定的5 s时长肌电数据,计算被测肌肉的积分肌电(iEMG)与平均功率频率(MPF)并填写视觉模拟评分(VAS)疼痛评估量表。结果模拟长航时飞行后,下背痛组左侧阔筋膜张肌和股直肌iEMG显著提升(P<0.05);其他肌肉iEMG在实验干预前后并无显著变化(P>0.05)。对照组左侧半腱肌MPF显著下降(P<0.05);其他肌肉MPF在实验干预前后并无显著性变化(P>0.05);对照组左侧阔筋膜张肌MPF显著低于下背痛组(P<0.05)。模拟长航时飞行前,下背痛组下背部疼痛等级显著高于对照组(P<0.01);飞行后,两组受试者下背部疼痛等级均有显著提升(P<0.01),但不存在组间差异(P>0.05)。结论4 h模拟长航时飞行会造成受试者表面肌肉屈髋肌(阔筋张肌和股直肌)的紧张和伸髋肌(半腱肌)的疲劳,会引起并加剧下背痛。

Objective To test the hypothesis that the long-time simulated flight induced low back pain may be caused by the muscle imbalance of pelvic relevant muscles,the effect of simulated long-time flight on the EMG of pelvic relevant muscles and the subjective pain level of the low back were observed so as to provide experiment data support for the prevention and treatment of long-time flight induced low back pain in pilots.Methods The surface electromyography of the muscles around the pelvis was measured in 8 subjects who had never experienced low back pain(control)and 8 subjects who had or had a history of low back pain for more than three months(LBP)before and after 4-hour simulated long-time flight.The integrated electromyography(iEMG)and mean power frequency(MPF)of all muscles were derived from the relatively stable 5 s-long EMG data within 30 s of relaxed static standing position.VAS pain assessment was also performed before and after the intervention.Results The iEMG of the left tensor fascia lata and rectus femoris were significantly increased in LBP after simulated long-time flight(P<0.05).There was no significant difference of iEMG in other muscles before and after experimental intervention(P>0.05).The MPF of left semitendinosus muscle in control group significantly decreased(P<0.05);the MPF of other muscles showed no significant difference before and after the experimental intervention(P>0.05);the MPF of left tensor fascia lata muscle in control group was significantly low than that in LBP group(P<0.05).Before simulated long-time flight,the level of low back pain in LBP group was significantly higher than that in control group(P<0.01);after the flight,the level of low back pain in the two groups was significantly in-creased(P<0.01),however there was no statistical difference between the two groups(P>0.05).Conclusion The 4 h simulated long-time flight caused tightness of the surface hip flexor muscles(tensor fascia lata and rectus femoris)and fatigue of the hip extensor muscles(semitendinosus),which may initiate and aggravate low back pain.