The Study On Relationgship Between Moment And SEMG Of Human Body Lower Limbs Under The Increasing Load

Objective:The aim of this study is to investigate the relationship between IEMG and momentof body hip、knee and ankle under the different load use the method of inverse dynamics，provide the oretical basis for electrical control, rehabilitation medicine, sports medicine, andthe implementation of the man-machine engineering.Methodology: Experiment of15subjects to squat with a heavy burden, load level of0%RM、15%RM、30%RM、45%RM、60%RM、75%RM and90%RM, and carries on thekinematics, dynamics and electronic data collection.Results:1、In the process of squat, main control of the lower limbs muscle for hip includeglutes maximus, semitendinosus and biceps femoris, next crouching, moment and IEMG aregradually decrease with the increasing hip Angle, moment reach maximum at the hip Angle60°, every muscle IEMG reach maximum at the hip Angle90°, in the process of squat, bothmoment and IEMG are all decreased with increment of hip Angle. Under the sameAngle,moment and IEMG botn increase with the increase of the load level.2、In the process of squat, main control of the lower limbs muscle for knee includerectus femoris、vastusmedialis and vastus lateralis, next crouching, moment and IEMGgradually increase with the decrease of the knee Angle, under30%RM, moment reachmaximum at the knee Angle70°, above the30%RM, moment reach maximum at the kneeAngle80°. The IEMG of rectus femoris reach maximum at the knee Angle120°, theIEMG of vastusmedialis and vastus lateralis reach maximum at the knee Angle90°. In theprocess of squat, Moment and IEMG gradually reduce with the increase of the knee Angle.Under the same Angle,moment and IEMG botn increase with the increase of the load level.3、In the process of squat, main control of the lower limbs muscle for knee include medialgastrocnemius、lateral gastrocnemius and peroneous longus,in the process of complete squat,the moment and IEMG value changes in the overall trend is the same as the hip and knee, butthe change is not big, moment reach maximum at knee Angle45°, the medial gastrocnemiusIEMG in55°achieve maximum, lateral gastrocnemius and peroneous longus IEMG reachedthe maximum at65°. Under the same Angle,moment and IEMG botn increase with theincrease of the load level. 4、The relationship between every joint moment、IEMG and joint angle:a、The formula of hip joint moment、IEMG and joint angle：Squat to down：Y=-68.276-0.649X1-1.455X2+0.412X4S quat to up：Y=-35.565-0.332X1+0.622X2-2.707x3+0.334X4Y：Moment X1：the IEMG of glutes maximus X2：the IEMG of biceps femorisX3：the IEMG of semitendinosus X4：Angleb、The formula of kn ee joint moment、IEMG and joint angle：Squat to down：Y=110.725+1.226X1-0.648X2S quat to up：Y=100.571+1.159X1-0.507X2Y：Moment X1：the IEMG of vastusmedialis X2：Anglec、The formula of an kle joint moment、IEMG and joint angle：Squat to down：Y=2.303-1.674X1S quat to up：Y=-2.649-1.329X2Y：Moment X1：the IEMG of medial gastrocnemius X2：the IEMG of lateralgastrocnemiusConclusions:1、Hip, knee and ankle moment trend along with the change of angle is basicallythe same，mean moment showed a trend of first increase and then decrease in thewhole squat，maximum moment appear nearby the rock bottom of squat，but due tothe different load will appear certain differences. The greater load level will producethe greater moment at the same angle.The hip moment is greater than the kneemoment and the ankle moment is the minimum.2、The trend of moment and IEMG of main control muscle of three joint momentis almost the same， but every muscle maximum IEMG appeared earlier thanmaximummoment.The greater load level will produce the the greater IEMG.3、Moment, IEMG and joint Angle exist complex relationship.