| Purpose:compression garments is considered to promote endurance,strength,speed,balance and fatigue recovery.At present,the effect of compression garments on neuromuscular control may also be one of the mechanisms leading to its improvement of ability.Muscle synergy,as a control theory with strong evidence of nerve origin,can effectively analyze the multi-dimensional neuromuscular control mode.We try to explore the neuromuscular mechanism of compression garments during running.Therefore,in this study,firstly,the biomechanical differences of the lower limbs before and after fatigue were detected,and the muscle synergy mode was obtained by using the non-negative matrix factorization.Combining the results of the biomechanical performance of lower limbs and the muscle cooperation pattern to explore the potential effects of compression garments on performance and the neuromuscular control mechanism.Method:The research 1 recruited 12 male subjects(age: 23.3±2.1,height: 177.2±6.6,weight: 73.3±5.7)to randomly wear compression garments and control shorts,and conducted two running fatigue experiments with increasing load,with an interval of at least 48 hours.The kinematics,dynamics,surface electromyography(for study 2),gas metabolism and blood lactic acid concentration data of the subjects before and after the fatigue were collected by Vicon motion capture system,Bertec three-dimensional treadmill,Noraxon wireless surface electromyography system(for study 2),k4b2 gas metabolism analyzer and portable lactic acid tester.Repeated measurement analyze is used to analyze the influence of compression garments factors and fatigue factors on lower limb joint angle,angular velocity,range of motion,moment,power and other parameters.The research 2 mainly analyzes the s EMG data in the experiment through the theory of muscle cooperative control.First,preprocess the original s EMG signal,eliminate the motion artifact by band-pass filtering(20-400hz),then get the complete envelope curve by low-pass filtering(20hz)after full-wave rectification,standardize it by using the maximum amplitude of each channel,divide the envelope curve into 10 cycles by using the gait cycle results in Study 1 after resampling,and then form the matrix to be decomposed by the average envelope curve of each channel.The script is written by Matlab,and the matrix to be decomposed is subjected to a non-negative matrix decomposition algorithm to extract N muscle synergy mode and activation curves,and the final value of N is determined by the variance interpretation degree greater than 90%.K-means cluster analysis was used to classify the synergies before fatigue into six reference baseline synergy modes,and then Pearson correlation coefficient was used to classify the synergy mode,and the average muscle weight and average activation curve of each coordination mode were obtained.In this study,Repeated measurement analyze is used to analyze the influence of compression garments factors and fatigue factors on the number of muscle synergy mode,and simple effect analysis is carried out when there is interaction.Welch T test is used to test the muscle weight,activation time,start time and end time of two groups of clothing conditions under the same fatigue and two groups of clothing conditions under the same fatigue,and the significance level of the above statistical analysis is p<0.05.Result:Research 1: There is a significant difference in fatigue time between the two clothing conditions(p=0.014),but there is no significant difference in the three parameters of maximal heart rate,oxygen uptake and fatigue degree between the two clothing conditions.In addition,when wearing CG,the blood lactic acid concentration after fatigue is higher(p=0.028),and there is no significant difference in blood lactic acid concentration after 15 mins rest,but the change of blood lactic acid concentration under CG condition is larger(p=0.048).Kinematics: For the ankle,the fatigue factor has a significant influence on the peak angle of dorsiflexion(p=0.008).For the knee,the fatigue factor has a significant influence on the maximum flexion angle(p=0.016)and touchdown angle(p=0.025)during the supporting period.compression garments have significant influence on the maximum(p=0.029),minimum flexion angle(p=0.01)and touchdown angle(p=0.029)of the knee joint.For the hip,fatigue factor has significant influence on the maximum flexion angle(p < 0.001),maximum flexion angular velocity(p=0.031)and joint range of motion(p < 0.001).Compression garments has a significant influence on the maximum(p < 0.001)and minimum joint angle(p < 0.001)of the hip joint,which shows that when wearing compression garments,the maximum flexion angle decreases significantly,while the minimum angle and extension angle increase.Dynamics: For the ankle,there is no significant main effect and interaction between compression garments equipment and fatigue factors on dorsiflexion moment,plantarflexion moment,shock absorption power and push-out power.For the knee,this study found that compression garments equipment has a significant main effect(p=0.035)on the peak value of the pedal-extension torque of the knee joint.Specifically,when wearing compression garments equipment,the peak value of the extension moment of the knee joint is significantly increased.For hip,compression garments and fatigue factors have not found any significant main effect and interaction on the moment and power.As for vertical stiffness and work,we found that fatigue factor has a significant impact on vertical stiffness and work of lower limbs(p=0.016),which showed that the vertical stiffness decreased after fatigue.When wearing compression garments equipment,the vertical stiffness and vertical work do tend to increase before and after fatigue,but there is no significant main effect.Research 2: In this study,there are six kinds of reference synergy.Fatigue factor and compression garments factor have no significant main effect on the number of synergy,but there is a trend of interaction(p=0.053).Synergy SYN2 did not appear in compression garments.The main muscle groups of each synergy mode did not change significantly under four conditions,and some cooperative minor muscle groups changed but their weights were lower.There are certain changes in the activation curves of synergy modes,mainly concentrated in SYN3 and SYN4.For SYN3 activation curves,the activation start time after fatigue is significantly delayed by nearly4%(p<0.001),and the activation starts from before touching the ground to after touching the ground.The activation time was significantly reduced by 36%(p=0.022)after fatigue under the control condition.For the activation curve of SYN4,under the control condition,the activation time after fatigue significantly increased by nearly 25%(p=0.013).Under compression garments,the activation time after fatigue is significantly reduced by 25%(p<0.001),and the activation start time after fatigue is significantly delayed by nearly 5%(p=0.021).Conclusion:1)Compression garments have the potential to improve sports performance,which has no obvious effect on physiology during exercise,but has remarkable effect in fatigue recovery.compression garments can reduce the knee flexion angle and increase the moment,which may help to improve the running economy and the conversion efficiency of mechanical energy.2)Compared with traditional methods,the muscle coordination model has higher repeatability,which is helpful to explain the changes and strategies of neuromuscular in combination with sports performance.Fatigue and compression garments equipment can affect the number of cooperative modes to a certain extent,but it is difficult to affect the weight of the main muscle groups that have already cooperated.3)The mechanical characteristics of lower limb compression garments can assist the runner to accomplish some mechanical goals and improve the cooperative working ability among muscles,which is helpful for the runner to use the muscle synergy of lower limb cross-joint muscles to maintain the overall work ability and reduce the loss of mechanical energy when dealing with fatigue. |
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