Typical Fatigue Risk And Characterization In Marathon Sports

With the deepening of the concept of national health,marathon has developed rapidly in China.Due to the particularity of the sport,the sports injuries that follow are increasingly prominent.Casualties caused by typical sports fatigue occur from time to time.This study takes the typical fatigue of marathon(muscle thermal fatigue caused by body thermal imbalance and muscle running fatigue induced by high-intensity exercise)as the object.Firstly,the research on heat exchange and heat balance of human internal tissues was carried out,and the human thermal fatigue model was built,and the numerical simulation verification and case comparison were carried out.Secondly,the human running fatigue risk experiment and the running fatigue risk characterization of ECG and sEMG signals were carried out to solve the running fatigue risk distance and risk threshold.Finally,the research on the rating evaluation of typical fatigue risk of marathon sports based on multi feature parameter fusion was carried out.The construction of a human thermal fatigue model.According to the thermal balance mechanism of human body,the mechanism of heat transfer and heat dissipation inside the human body was analyzed,and the mathematical model of heat transfer and heat dissipation between the internal tissue layers of the human body was obtained.The influence factors of human thermal fatigue in marathon were analyzed,and it was shown that the multi-factors of human body’s metabolic heat production,heat dissipation,environment,sportswear,and exercise work were the main influencing factors.And the differential governing equation for the distribution of the human muscle temperature field was constructed.Human thermal fatigue risk simulation verification and case comparison.According to the human thermal fatigue model,the boundary conditions of-5 ℃,5 ℃,15 ℃,25 ℃ and 35 ℃ are set for the human temperature changes in different environments.Through the simulation of Theseus-FE software,the distribution of human temperature field exposed to different temperatures and the temperature change law of the core layer and skin layer are obtained:when the human body is exposed to a low temperature environment(-5 ℃)for a long time(3 hours),the temperature of the human skin layer and the core layer decreases rapidly,risk of human body temperature loss,when the human body is exposed to the high temperature environment(35℃)for a long time(3h),the temperature of the skin layer and core layer of the human body will rise,leading to the risk of sudden cardiac arrest due to overheating of the human body.The comparison with the relevant medical laws verifies the accuracy of the actual application of the marathon thermal fatigue model.For the case of Baiyin "5.22" Marathon accident,weather conditions such as temperature,wind speed,wind direction and humidity at that time and disaster scenario conditions such as slope and altitude were extracted,and the time and location of human body temperature loss risk were simulated by numerical method.The simulation results were compared with the time-space relationship of accident casualties,and the solution results were basically consistent with the real situation The simulation results were compared with the time-space relationship of accident casualties,and the solution results were basically consistent with the real situation.The temperature change of the human body in the laboratory marathon running fatigue risk experiment was simulated,and the temperature change law of the human body with different running distances of the half marathon and the fatigue feeling value of the subjects during the marathon running were obtained.The regression analysis was carried out between the temperature of the abdominal core layer and the fatigue feeling of marathon running,and the best part of the fitting effect was the temperature of the abdominal core layer.The relationship between the temperature of the abdominal core layer and the feeling of running fatigue was established,and the quantitative evaluation of the fatigue feeling of marathon running was realized.Study on the characterization of sEMG signals reflecting the risk of fatigue in marathon running.Recruit 20 subjects for the fatigue risk experiment of marathon running,and carried out the incremental load experiment according to the test results of the subjects’ maximal oxygen uptake.The joint analysis and the analysis and comparison of the results of the exercise lactate threshold determined that the pace corresponding to 80%of the VO2max intensity was the risk pace threshold for the subject’s running fatigue risk,and the medial gastrocnemius and rectus femoris were determined as the test muscles which represent running fatigue risk.According to this pace,subjects were subjected to a laboratory treadmill half-marathon exercise experiment,and the sEMG signals of the test muscles were collected in real time,and the time domain,frequency domain,and nonlinear characteristic parameters of the sEMG signals were obtained,perform regression analysis with exercise duration,and obtained the mathematical model of characteristic parameters.According to the significance analysis of characteristic parameters,iEMG,MF and complexity were selected as the key characteristic parameters to characterize the risk of running fatigue of the sEMG signal on the surface of the medial gastrocnemius muscle.Select iEMG,MPF and approximate entropy as the key characteristic parameters to characterize the fatigue risk of running on the surface of the rectus femoris sEMG signal.Study on the characterization of ECG signals reflecting the fatigue risk of marathon running.Collect the time domain,frequency domain,and nonlinear characteristic parameters of the subject’s ECG signal in real time,and performed regression analysis with the exercise duration to obtain the mathematical model of the characteristic parameters.The running fatigue degree of the subjects was solved,and the Pearson correlation coefficient between the characteristic parameters and the running fatigue threshold was calculated.And the SDNN,LFnorm,HFnorm,and sample entropy of the ECG signal were selected as the key characteristic parameters for the judgment of the subjects’ running fatigue risk.Recruit 20 subjects(marathon beginners)who had not participated in the half-marathon for half-marathon running,and compared the heart rate and ECG characteristic parameters of the aforementioned subjects(marathon runners),the marathon beginners had higher risk of running fatigue.The running fatigue risk questionnaire survey was conducted on the aforementioned subjects during the experiment,and the variation trend of human running fatigue degree and the variation trend of running fatigue risk characteristics were obtained.Validation of mathematical representation model of ECG and sEMG characteristic parameters and evaluation of typical fatigue risk levels in marathon.Based on the mathematical representation model of the characteristic parameters,analyze and obtain the fatigue risk threshold and running fatigue risk distance of relevant characteristic parameters,recruit 10 subjects for outdoor half-marathon,and verify the accuracy of the mathematical representation model of ECG and sEMG characteristic parameters.Using the key characteristic parameters of temperature,ECG and sEMG,and using the method of support vector machine to build typical fatigue risk level evaluation model for marathon.The model has an accuracy of 70.0%,82.1%,and 90.5%for the three risk levels of typical fatigue in marathon sports,and the overall evaluation accuracy of physiological feature information fusion was 86.3%..This study provides scientific reference for the risk of body temperature loss,sudden death,sports injury in typical fatigue of extreme sports,and provides certain technical basis for the prevention and treatment of occupational diseases of personnel under special working conditions(extreme temperature,high intensity).