Biomechanical Analysis Of Chain Hard Pulling Training On Unstable Support Surface

Research purpose: Based on surface electromyography technology and Vicon motion capture system,analyze the relevant parameters of chain hard pulling on unstable support surface,and explore the differences between traditional hard pulling,chain hard pulling and hard pulling on unstable support surface.Research methods: 15 male students majoring in physical education of North China University were recruited as subjects,with an average age of 22 ± 2.7 years.The subjects were required to have a strength training foundation of more than one year or a hard pull training foundation of more than half a year,and there were no spinal column,waist and lower limb joint injuries and diseases that could affect the completion of this research plan.The experiment was divided into 8 groups under different intervention conditions（35%1rm barbell,35%1rm barbell + chain,35%1rm barbell + balance training pad,35%1rm barbell + Chain + balance training pad,65%1rm barbell,65%1rm barbell + chain,65%1rm barbell + balance training pad,65%1rm barbell + Chain + balance training pad）.The centripetal stage data of a hard pull with high signal quality were collected for analysis.IEMG（integrated electromyography）and RMS（root mean square electromyography）,MPF（mean power frequency）,MF（median frequency）,changes of spine displacement in coronal plane and peak ground reaction force were statistically analyzed.The test muscles were: right and left rectus abdominis,transversus abdominis,erector spinalis,rectus femoris and lateral femoris.Results:（1）comparison between barbell group and barbell+ Chain Group: under 35%1rm and 65%1rm of chain group,the average i EMG of bilateral rectus abdominis,transverse abdominis and erector spinalis was always greater than that of traditional group（p<0.05）.The difference of muscle work percentage of left and right erector spinalis in chain group was smaller than that of traditional group,and there was no significant difference in the displacement of spine in human anatomy plane（p>0.05）;（2）Comparison between the barbell group and the barbell + balance training pad group: when the traditional hard pulling was performed on the unstable support surface,the i EMG average values of the left and right rectus abdominis,transverse abdominal muscle,erector spinalis,rectus femoris and lateral femoral muscles at 35%1rm and 65%1rm were always greater than those on the stable support surface（p>0.05）,and there was no significant difference in the displacement of the spine in the coronal plane and horizontal plane（p>0.05）;（3）After comparison between the barbell + chain group and the barbell + Chain + balance training pad group,it was found that except that under the condition of 65%1rm,the i EMG of the right rectus femoris muscle during hard pulling on the stable and unstable support surfaces after t-test（p<0.05）,there was no significant difference in the other statistically analyzed i EMG（p>0.05）,and there was no significant difference in the displacement of the spine in the human anatomical plane（p>0.05）.Research conclusions:（1）under the conditions of 35%1rm and 65%1rm,chain hard pulling can show better stimulation effect in the core muscle group,produce greater peak ground reaction,enhance the muscle activity and muscle fiber recruitment of the core muscle group,achieve better training effect,and show that the left and right balance of the vertical spine muscle,the main force generating muscle group of chain hard pulling,is better than the traditional hard pulling,and the force is more balanced;（2）Under the conditions of 35%1rm and 65%1rm,hard pulling on the unstable support surface can enhance the bilateral force balance of the lateral femoral muscle,the main force generating muscle group of the lower limb during hard pulling,enhance the stability of the lower limb,and improve the peak ground reaction force during traditional hard pulling;（3）Hard chain pulling can improve the intensity of muscle activity and the number of muscle fiber recruitment,and this effect is more obvious in the core muscle group,which can produce greater peak ground reaction.At the same time,hard chain pulling also reflects that the left and right surface EMG signals of the vertical spine muscle,the main force generating muscle group,are more balanced,and the force is more balanced.