| Purpose: The accumulation of exercise-induced muscle fatigue leads to an increased risk of injury,and it is not limited to the local joints where the fatigued muscles are located.Severe muscle fatigue during exercise can cause deformation of the whole body and a high risk of falls.This is an important basic theoretical problem in the study of exercise physiology.It is also an important practical application issue of competitive sports.The direct measurement method and indirect measurement method of muscle fatigue are used to detect the recovery process of exercise-induced muscle fatigue,find the characteristics of muscle fatigue and recovery,and select the appropriate evaluation method of muscle fatigue.At the same time,the mathematical model of muscle fatigue is verified,which is suitable for the sports field.The mathematical model provides a theoretical basis.Method: 32 ordinary college students(male: 16;female: 16),using Mark 10 to test MVC three times and set resistance load according to 30%,40%,50%,60%,70% of their own MVC;knee flexion and extension process In,the metronome is used to set the frequency to 30beats/min,and the electromyography device and three-dimensional accelerometer are used to synchronously collect the electromyography data and acceleration of the knee extensor muscles.After MATLAB R2019 b programming and wavelet transform processing,the EMG data obtains the instantaneous average frequency and instantaneous median frequency.Linear regression is used to describe the decreasing trend of maximum power,IMNF,and IMDF as the number of knee extensions increases.At the same time,the slope of IMNF and IMDF is compared with "0".During the recovery process,the Omron sphygmomanometer tests the heart rate and blood pressure every 1 minute,and reports the Borg scale value every 20 s.The calm heart rate and the recovered heart rate after the test were tested for independent samples,and curve estimation was used to describe the change of the Borg value.Results: 1.The intra-group correlation coefficients of the three MVC test results for men and women were 0.97 and 0.98,respectively,and there was no significant difference between the three measurements(P>0.05).2.The maximum power output changes linearly.Under the same load,it decreases with the increase of time;under different loads,the greater the load,the greater the maximum power output.Female subjects applied a load greater than 60% MVC.As the load increased,the maximum power decreased slowly.3.The slopes of the EMG data of 32 subjects are all negative,and compared with "0",there are significant differences(P<0.01),and the decline rate under 50% MVC for men is less than 40% MVC.4.During the recovery process,the heart rate and blood pressure after 5 minutes of rest were not significantly different from the calm heart rate and blood pressure before the test(P>0.05).The Borg value showed an exponential change trend during the recovery process,R2 was all greater than 0.994,and the Borg value recovery rate first increased and then decreased.5.Using experimental data to verify the mathematical model,the fatigue rate has a linear trend.Conclusion: 1.In resistance training,women's load setting does not exceed 60% of their own MVC when it is necessary to complete the action while avoiding wrong actions or borrowing force.2.The wavelet change analysis of surface EMG is superior to other indicators.It can detect muscle fatigue and the accumulation of muscle fatigue.3.During the recovery process,the heart rate and blood pressure recover quickly.It is recommended to use the psychophysical scale for evaluation during the recovery phase.4.Verify the muscle fatigue model.It is found that the fatigue rate in this mathematical model changes exponentially,and the test results of lower limb muscles are used to verify linear changes. |
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