Study On The Changing Characteristics And Intervention Of Neck And Shoulder Muscle Fatigue Caused By Long-term Sitting And Using Mobile Phone

Objectives:By investigating the changes of surface electromyographic(s EMG)fatigue index of neck and shoulder muscles and neck flexion angle in the process of using mobile phone while sitting for a long time,as well as the effects of using mobile phone while sitting for a long time on flash fusion frequency,shoulder flexibility,visual analog score and muscle strength,this study provides experimental basis for suggesting reasonable duration of mobile phone use.And to observe the effect of neck muscle stretching activities on the recovery of neck and shoulder muscle fatigue after using mobile phone for a long time sitting posture,so as to provide reference for promoting the recovery of neck and shoulder muscle fatigue.Methods:Two experiments were conducted on 20 non-physical education major college students.VAS score,flash fusion frequency,FMS shoulder flexibility,and maximum voluntary isometric contraction strength(MVC)of posterior extension were performed before and after 90 min of sitting position with mobile phone.The s EMG signals of the upper and middle fascicles of the neck trapezius muscle and sternocleidomastoid muscles were recorded during the measurement of MVC.After using the mobile phone,neck muscle stretching and sitting for the same length of time were carried out respectively,and all indicators were measured again after sitting and stretching.When testing neck extension MVC,the subject conducted neck extension test on the pre-adjusted Back-Check isometric strength tester.Each test lasted 10 seconds,and the s EMG signal was recorded.The electromyographic signal selected integrated electromyographic signal,root mean square amplitude,average amplitude,mean power frequency and median frequency indexes.The changes of various indexes before and after using mobile phone,sitting and stretching were compared respectively.During the use of mobile phone,JVC camera was used to make video recording every five minutes from the fixed camera position on the side of the subject.After the video recording,Kwon3 D system was used to dot the subject’s tragus and seventh cervical vertebra to obtain the cervical flexion Angle of the subject and observe the changes in the cervical flexion Angle during the use of mobile phone.Result:(1)VAS score was significantly increased,flash fusion frequency,shoulder flexibility and neck extensor strength were significantly decreased after 90 minutes of mobile phone use(p < 0.01).During the use of mobile phone,the head extension Angle increased continuously during the use of mobile phone,and significantly increased from 25 minutes(p < 0.01).(2)IEMG,RMS and MA values of the upper and middle tracts of the trapezius muscle and sternocleidomastoid muscle were significantly increased after 90 minutes of mobile phone use(p < 0.01);The MPF slope and intercept of the right trapezius upper bundle were significantly decreased(p < 0.05),the slope of the left trapezius upper bundle,sternocleidomastoid MF and the intercept of the left trapezius upper bundle were significantly decreased(p < 0.05),and the intercept of the right sternocleidomastoid MF was significantly higher than that of the left before and after using the mobile phone(p < 0.05).(3)VAS score and flash fusion frequency were decreased,the distance between two hands was decreased,and the extensor strength of neck was increased significantly after sitting and stretching(p < 0.01).The change rate of VAS score before and after stretching was significantly decreased compared with sitting,and the change rate of left shoulder flexibility was significantly increased compared with sitting(p < 0.05).(4)The IEMG,RMS and MA values of the upper and middle tracts of trapezius muscle on both sides and sternocleidomastoid muscle after sitting and stretching were significantly lower than those before sitting and stretching(p < 0.01);After sit-in,the MPF slope of the right trapezius fasciculi increased significantly(p < 0.01),and the MF intercept of the right sternocleidomastoid muscle before sit-in was higher than that of the left(p < 0.01).After stretching,the change rate of RMS and MA in the right trapezius muscle bundle decreased more than that in sitting,and there was a significant difference(p < 0.05).The change rate of IEMG in the left sternocleidomastoid muscle before and after sitting,and the change rate of MA before and after stretching were significantly higher than those in the right muscle(p < 0.05).The change rate of MPF slope of the right sternocleidomastoid muscle before and after stretching was significantly higher than that of the left(p < 0.05).Conclusion:(1)Long-term use of mobile phones can cause increased subjective fatigue,decreased shoulder flexibility,decreased neck muscle strength,resulting in fatigue of the trapezius muscle bundle,the middle bundle and the sternocleidomastoid muscle.(2)Forward head angle increased significantly after continuous use of mobile phone for more than 25 minutes,increasing the risk of neck muscle fatigue.(3)Neck muscle stretching program can relieve neck muscle fatigue caused by long-term use of mobile phones.