Effect Of Low Back Pain For Dance Students On Muscular Endurance,Muscular Trength And Explosive Force Of Their Trunk Muscle

Objective:Low back pain refers to a syndrome with lumbosacral, buttocks, lower back painas the main symptom.It can be caused by many factors.It is a manifestation of theneuromuscular skeletal disorders. Low back pain is common not only in the ordinarypeople but also in sports students.Many programs which sports students are engagedin need to be started by low back.Therfore,it has a great influence on health and sportslife of the students in professional sports.According to scholars’ survey,there are morethan75%of the sports students that are with varying degrees of low back pain.Dance students is high risk of low back pain,because they often bearwaist rotation, flexion and extension movements and even a lot of action close to the limit.Often bearing the load of high-strength result in a heavy burdenon the waist,so as to easily lead to chronic low back pain.This study was designed to explore the impact of low back pain on muscle strength, endurance and explosive of dance students.And this study also try to learn the difference ofrelevant parameters of the trunk muscle between the dance students suffered from low back pain and normal dance students.We also try to find direct effecton motor ability of trunk muscle of dance students.We hope to guide clinical treatment and give therapeutic advice.We hope to put forward some training advice for coaches in order to prevent dance students from low back pain.Methods:The instrument of this study is American NORM isokinetic system and8-channel Noraxon surface EMG Telemetry System(sEMG), Model: Tele Myo2400T,software version: Myo Research XP Master Package Ver:1.03.05.Totally32dancestudents from Tianjin Sports University are chose as subjects.There are16subjectsthat are with low back as the experimental group,age21.56±1.031y, height163.75±1.528cm, weight53.28±1.291kg.16subjects without low back pain alsochose as the control group, age21.69±1.078y, height163.38±1.586cm, weight53.19±1.276kg.Use medical examination to exclude organic damage leading to lowbak pain.All the samples can participate the normal training and competition.Three angular velocity (30degrees/s,90degrees/s,120degrees/s) is used inisokinetic system to test trunk flexor and extensor muscle.Subjects do their best toflex and extent trunk for5times in two angular velocity of30degrees/s,90degrees/s.The rest time is30s.When the velocity is120degrees/s,subjects should do theirmaximum effort and maximum speed to flex and extent trunk for15times.Test data isrecorded and saved automatically by the system.Also erector spinae fatigue test:use subjects’ own weight for erector isometricload test.Method:Subjects are prone.Fixed their lower extremities and buttocks (lowerthan spina iliaca)with straps on a test benchon about90cm.During the test subjectsshould put hands after head and extent arms.Subjects should make trunk hang in theair and try their best to make trunk parallel with the ground for60seconds.Thesurface EMG of bilateral erector spinae is recorded.Results:Trunk extensor:During the isokinetic test,PT、PT/BW in the pain group and thenormal group both decrease with increased speed.At three kinds of speed,PT、PT/BWin the pain group are less than the normal group.And at the speed of30degree/s and90degree/s,the difference is significant(P<0.05).AP in the pain group and the normalgroup both increase with increased speed.At three kinds of speed,AP in the pain group is less then the normal group,but the difference was not significant(P>0.05).Trunk flexor:During the isokinetic test,PT> PT/BW in the pain group and the normal group both decrease with increased speed.At three kinds of speed,PT、PT/BW in the pain group are less than the normal group.But the difference is not significant(P>0.05).AP in the pain group and the normal group both increase with increased speed.At three kinds of speed,AP in the pain group is less then the normal group,but the difference was not significant(P>0.05).F/E:At the speed of30degrees/s and90degrees/s,F/E in the pain group is greater than the control group and the difference is significant(P<0.05).While at the speed of120degrees/s,the difference is not significant(P>0.05).Static endurance of The erector spinae:Whether the pain group or the normal group, MPF, MF slope(negative) of the right side erector spinae muscle is smaller than the left side.The MF slope of both sides of the pain group has significant difference(P<0.05).While MF slope of bilateral erector spinae of the normal group had no significant difference(P>0.05).Compared the MPF、MF slope of the ipsilateral erector spinae of two groups,the pain group(negative) is smaller than the normal group,but the significance is not different(P>0.05)。Conclusions:This study find that trunk muscle strength of dance students with low back pain decrease.And trunk extensor strength decrease more obviously.Especially in the low speed of trunk flexion and extension, this effect is more significant.At the same time,muscle strength of trunk flexor and extensor of dance students with low back pain is not balanced.The decreased muscle strength of trunk extensor is the main cause.Besides,compared to normal dance students,the dance students with low backpain are with erector spinae of decreased static endurance.And right side erector spinae of students with low back pain are more likely to be with fatigue.