The Effect Of Lumbar Extensor Muscles Fatigue On Biomechanics Characteristic Of Upper Limb Whiping Movement

Lumbar extensor muscles and affiliated group are muscles and ligaments,which around the lumbar,and are an important parts of the body' s core muscles.Studies have shown that lumbar extensor muscles play an important role in support body weight,transmission and intergrated limbs power,buffer impact,protect the spine and internal organs.Whiplash movement is one of the most basic action for human body,whip is common in sports technology.In some sports events,such as badminton?tennis?table tennis,whiplash movement is the primary technical movement type.And these sports events often have continuous multiple rounds upper limb whiplash movement.In this moment,the athieles showed a continuous? high strength? large power whiplash movement.In the process of many rounds of whiplash movement,lumbar extensor is to maintain the trunk and body balance and to deliver and integrated the power of limbs.This will make lumbar extensor under high load for a long time,so it easy to fatigue.Summarized various research results,we can be found that athlete lower back pain has a very close connection with lumbar extensor fatigue accumulation caused by long-term training.This suggests that there is a situation that athletes are not completely restore from lumbar extensor fatigue,then they went into a new round of training or competition.However research status at home and abroad focuses on the effect of lumbar extensor fatigue on basic motor function of human body,rather than the effect of lumbar extensor fatigue on complex motion technique.To sum up,whether the structure of whiplash will changed after lumbar extensor fatigue,what kind of negative influence will happen when these movement structures change,if lumbar extensor fatigue have negative influence on upper whiplash movement,what is it mechanism.In addition whether lumbar extensor fatigue will increased damage risk of upper whiplash movement.For research purposes,we measurement 16 badminton players,they are all state two or one badminton athletes.Collect their body biomechanical indicators information when they full power smash.We use motion capture system with infrared camera to track 52 mark points which were pasted on the subject,aim to get body kinematics information of subjects;By using of Kistler force platform to measurement ground reaction force produced by subject when they smash;Using Noraxon telemetering electromyography measurement system to collect electromyographic signal produced by muscles of trunk and upper limbs.By comparing above-mentioned indexes before and after lumbar fatigue,analysis the reason of the effect of lumbar fatigue on upper limbs whiplash movement.By comparing the kinematics,kinetics and myoelectricity indexes ofsubjects,we get the following conclusions:1? In the swing stage of upper limbs whiplash movement,due to lumbar extensor fatigue,the relative magnitude between hip and shoulder were changed,so that decreased the rotating angular of trunk and upper limbs' some sections,resulting in the decreased generation and transfer efficiency of angular momentum.finally,the speed of terminal part of upper limbs were going down obviously.2?Lumbar extensor fatigue does not change the general pattern of each part of upper limbs in turn to accelerate and transfer momentum moment.However,lumbar extensor fatigue extend the time difference between upper extremity and trunk.3?Lumbar extensor fatigue affects the kinematics and kinetics characteristics of lower extremity joints in the pedal process,and change the balance model in whip movement,make the body balance appear more forward position strategy.4?The reason of drop whip effect,rhythm changes between joints,movement structure change during whip caused by lumbar extensor fatigue,is not due to fatigue has reduced the ability of the lumbar extensor muscle to transmit and integrate the force of the extremities-But due to the fatigue of lumbar extensor muscles,the ability of neuromuscular control decreased.This result in the activation of major muscles that cause the trunk buckling and rotation decreases.In this way,the ability of the body to produce and transmit the moment of momentum is reduced.5? The reduced trunk neuromuscular control ability and more forward balancing posture strategy,which is caused by fatigue of the lumbar extensor muscles,cause a change in the load of the lumbar and knee-joint.Therefore,the risk of lower back and lower extremity knee joint injury will be increase.In addition,the reduced of neuromuscular control ability also could cause the resist disturbance ability of body is decline,and increase the chance of accidental damage.6? In allusion to the effect of lumbar extensor fatigue on upper limbs whiplash technique,should increase nerve-muscle activity during routine training,thus the muscle control ability of the nerve is improved.In addition,we should emphasize the integrality and systematicness of muscle and motion structure training during routine training,this can effectively prevent local muscle fatigue and the risk of injury.