The Research Of The Relationship Between Mobilization Of The EMG And The Force Of The Quadriceps

Objective:The aim of this study is to investigate the relationship between IEMG% and the ability of contraction of quadriceps, by studying the characteristics of the torque of knee extensors and IEMG% in voluntary isometric contraction at different knee angles and different load conditions.Methodology:Eight young healthy men volunteered to participate in the study. Participants were requested to perform voluntary isometric contractions at different conditions using Biodex System 3 Isokinetic Testing and Training System. Simultaneously, the SEMG signals were collected from retus femoris(RF),vastus medialis(VM) and vastus lateralis(VL), to analysis IEMG% and the contraction characteristics of quadriceps at different conditions.Results:1,In maximal voluntary isometric contraction,it is knee joint 75°flexion that the peak torque of knee extensors emerges.2,Below the load of 80%MVC, the IEMG% of the sum of RF,VL and VM increases with the increasing of knee angle flexion; Above the load of 80%MVC, the IEMG% of the sum of RF,VL and VM increases with the increasing of knee angle flexion, but there is a decrease only at knee joint 60°flexion.3,The IEMG% of the sum of RF,VL and VM increases with the increasing of the torque of knee extensors at every knee angle which we tested. The IEMG% change of RF and VL is in line with the change of the sum of RF,VL and VM, but the VM is different.4,At different loads and angles, the contribution ratio of RF,VL and VM to the sum of RF,VL and VM is 1:1:1. 5,The correlation between knee angle and peak torque of knee extensors and knee angle and IEMG% are low;while the correlation between peak torque of Knee extensors and IEMG% is high.The regression equation between the IEMG% of the sum of RF,VL and VM and the torque of knee extensors is: y=0.017+0.004x; The regression equation of the torque of knee extensors speculated by the IEMG% of the sum of RF,VL and VM and knee angles is: y=3.366+171.223 x1 (IEMG%)+0.43 x2 (knee angle)Conclusions:1,The torque of knee extensors,the angle of knee flexion and the IEMG% of the sum of RF,VL and VM have relevance on some degree.2,There is regression equation presenting the torque of knee extensors speculated through the angle of knee flexion and the IEMG% of the sum of RF,VL and VM:y=3.366+171.223 x1 (IEMG%)+0.43 x2 (knee angle)...