The Optimal Walking And Running Speed For Prevention And Treatment Of Low Back Pain Is Discussed Based On The Coupled Simulation Of Intra-abdominal Pressure And Lumbar Spine Load Based On OpenSim

Objective:To build a full-body musculoskeletal model with intra-abdominal pressure module in Opensim.By the computer simulation,to investigate the biomechanical characters of waist and hip and the difference of loading compensation mechanisms in six exercises(slow/fast walking,2-5m/s running)with normal and low intra-abdominal pressure,and to determine the best way of prevention and rehibitation of low back pain.METHODS:Based on the modeling function of Open Sim,some of the joint parameters of the Raabe's full-body model were modified,and the intra-abdominal pressure module was added.Then computational accuracy of the model was preliminarily verified by comparing simulation data and electromyogram data.Based on the improved model,the kinematics data of six kinds of exercise(1.2m/s slow walking,1.8m/s fast walking,2m/s jogging,3m/s running,4m/s running and 5m/s running)were input,and the differences of peak loading of disc and muscle between different gaits with different intra-abdominal pressure conditions were analyzed by adjusting intra-abdominal pressure module.Results:When the intra-abdominal pressure was normal,the posterior extensor muscles(erector spinalis,gluteus maximus)which maintain the stability of the trunk were recruited more during running than during walking.The peak values of erector spinae muscle activation were47.1%,64.8%,94.2% and 100% at 2-5m/s running speed,respectively,which were higher than those at 43.3% and 23% at fast and slow walking speed.The peak values of gluteus maximus muscle activation were 64.1%,88%,100% and 98.7% at 2-5m/s running speed,respectively,which were higher than those of 37.6% and 30.7% at fast and slow walking speed.The recruitment of lumbar spine stability muscles(quadratus lumbar,multifidus)is also higher during running than during walking.The peak values of quadratus lumborum muscle activation were 3.5%,4.8%,6.6% and 12.9% at 2-5m/s running speed,respectively,which were higher than those at 2.7% and 1.8% at fast and slow walking speed.The peak values of multifidus muscle activation were 11.9%,16.2%,22.4%,and 37.8% at 2-5m/s running speed,respectively,which were higher than those at 5.6% and 3.1% at fast and slow walking speed.At the same time,running(> 80%)produced/required much more intra-abdominal pressure than walking(<20%).At 2-5m/s running speed,the peak activation degrees of the intra-abdominal pressure module were 82.8%,98.6%,100%,100%,respectively,which were much higher than that of 19.8% and 12% at fast and slow walking speed.The lumbar disc loading during running was generally higher than that during walking.At 3-5m/s running speed,the average peak axial compression force of the intervertebral disc was 1388 N,1559.7N and 1733.9N,respectively,which exceeded the upper limit of the optimal axial loading range of the intervertebral disc(300-1200N).But the intervertebral disc loading produced by fast walking and 2m/s jogging were similar,and their ranges were well within the optimal disc stimulation loading(300-1200N).After the removal of the intra-abdominal pressure module,the activation degrees of lumbar and hip muscles and lumbar disc loading in running were higher than that in walking,and the increase rate of axial intervertebral disc loading in running(>35%)was much higher than that in walking(<10%).The axial loading of lumbar intervertebral disc increased by 6.4%(1231.1N)in fast walking,but increased by 36.2%(1908.4N)in 2m/s jogging.However,the increase rate of the lumbar and hip muscles' peak-strength during running was only slightly higher than that of walking.Conclusion:1.Compared with walking,running can better activate the core muscle group and maintain the homeostasis of intra-abdominal pressure,but it is highly dependent on intra-abdominal pressure.If the intra-abdominal pressure is insufficient,it is easy to cause musculoskeletal compensation.2.For people with normal intra-abdominal pressure,slow running(2m/s)is the better exercise to prevent low back pain.3.For patients with low back pain,who has lower abdominal pressure,fast walking(1.8m/s)is the better intervention means.Meanwhile,lumbar and hip training is recommended to make up for the deficiency of fast walking on activation of core muscle group.