Effects of biomechanical parameters of spinal manipulation: A critical literature review

Spinal manipulation is a manual treatment technique that delivers a thrust,using specific biomechanical parameters to exert its therapeutic effects.These parameters have been shown to have a unique dose-response relationship with the physiological responses of the therapy.So far,however,there has not been a unified approach to standardize these biomechanical characteristics.In fact,it is still undetermined how they affect the observed clinical outcomes of spinal manipulation.This study,therefore,reviewed the current body of literature to explore these dosage parameters and evaluate their significance,with respect to physiological and clinical outcomes.From the experimental studies reviewed herein,it is evident that the modulation of manipulation’s biomechanical parameters elicits transient physiological responses,including changes in neuronal activity,electromyographic responses,spinal stiffness,muscle spindle responses,paraspinal muscle activity,vertebral displacement,and segmental and intersegmental acceleration responses.However,to date,there have been few clinical trials that tested the therapeutic relevance of these changes.In addition,there were some inherent limitations in both human and animal models due to the use of mechanical devices to apply the thrust.Future studies evaluating the effects of varying biomechanical parameters of spinal manipulation should include clinicians to deliver the therapy in order to explore the true clinical significance of the dose-response relationship.

Optimization of the key position parameters for tractor steering wheel based on a driver’s arm muscle load analysis

Steering wheel is the most frequently used manual device in tractors,whose position directly affects the handling comfort of the driver and fatigue degree of the arm muscles.In this study,the biomechanical modelling software AnyBody was used for an inverse kinetics analysis of the rotation process of tractor steering wheel,calculate the muscle activation degree of the driver’s arm and compare it with the calculated results of surface EMG tests to verify the reliability of the biomechanical model.Based on the biomechanical model,the effects of three position parameters(steering wheel inclination,front-back distance,and upper-lower height)on the activation degree of the driver’s arm muscles were evaluated.The results demonstrated that steering wheel inclination has the most significant effect on the degree of muscle activation,followed by the upper-lower height and then front-back distance.Considering the interaction among factors,a regression orthogonal test was designed,and the test results revealed that the minimum muscle activation(1.2887)can be obtained with the steering wheel inclination of 31°,front-back distance of 431 mm and upper-lower height of 375 mm.The findings can provide a reference for optimizing the structure and position parameters of tractor steering wheels.