Effects Of Long-time Simulated Flight On Pelvic Position And Related Muscles In Adult Males

Objective: Pilots often perform long-duration flight missions and most of them have low back pain.In order to find the effects of pelvic position and related muscle on low back pain in pilots and provide evidence support for the treatment and prevention of high-risky low back pain in pilots,this research measured pelvic position(pelvic tilt)and related muscle’s EMG before and after 4-hour simulated flight.Methods: This study enrolled 16 adult men without physical training experience and regular exercise as subjects.8 of the subjects without low back pain were defined as N group,the other 8 of the subjects with low back pain were defined as Y group.All subjects were subjected to a 4-hour simulated flight intervention,X-ray image of pelvic was taken before and after the intervention to measure the static position of the pelvic,The three-dimensional infrared high-speed motion capture system was used to measure the dynamic changes of the pelvic when standing within 30-second,these two methods were used to measure pelvic tilt(PT).The integral electromyography(i EMG)and mean power frequency(MPF)of pelvic-related muscles(rectus abdominis,tensor fasciae latae,rectus femoris,erector spinae,multifidus,gluteus maximus,biceps femoris long head,semitendinosus)were measured with EMG device simultaneously with the threedimensional infrared high-speed motion capture system,the pain level were obtained by completing VAS questionnaire.Results: After 4-hour simulation flight,both groups’ pelvic tilt measured by tw o methods did not change significantly,The i EMG of the left tensor fascia l-a ta muscle(pre:10.86±4.85 u V×s,post:13.64±3.87 u V×s,P<0.05)and the rectus fem oris muscle(pre:9.50±3.15 u V×s,post:15.05±9.31 u V×s,P<0.05)were significantly improve in Y group;The MPF of the left tensor fascia lata muscle in N grou p was significantly lower than Y group(N:0.55±0.13 Hz,Y:0.76±0.22 Hz,P<0.05),an-d the MPF of left semitendinosus muscle in the N group was significantly de-creased(0.70±0.28 Hz,0.56±0.22 Hz,P<0.05);The level of low back pain w as s-ignificantly increased in both groups(N-pre:0.00±0.00,N-post:2.50±2.27,P<0.01;Y-pre:2.25±1.16,Y-post:3.88±0.99,P<0.01).Conclusion: 4-hour long simulated flight will not cause pelvic position change;4-hour long simulated flight will cause tension in the surface flexor muscle and fatigue in the extensor muscle;4-hour long simulated flight will cause and aggravate low back pain.