Finite Element Analysis Of EIM And Its Application In Experimental Research Of Muscle Fatigue

In recent years,various wearable devices combined with sports and fitness,represented by smart watches and sports wristbands,have gradually been highly favored.As an unavoidable physiological phenomenon,muscle fatigue has provoked intense attention in the fields of daily life,rehabilitation medicine,and sports.But it was rarely applied to the wearable devices.Electrical impedance myography(EIM)uses electrical impedance to evaluate the characteristics of local muscle or muscle groups and it is an effective tool for detecting muscle fatigue.Compared with the common surface electromyography(sEMG)for assessing muscle fatigue,EIM has the advantages of large signal amplitude,controllable frequency,and easier pretreatment,which can provide a low complexity and high feasibility wearable realization scheme for real-time monitoring of muscle fatigue conditions.In this dissertation,the finite element solution method was applied to obtain the optimal electrode configuration for EIM measurement on the three-dimensional arm finite element model.At the same time,the experimental study of muscle fatigue based on EIM principle was carried out on biceps brachii under optimal electrode configuration,and the results were compared with sEMG to verify the feasibility and rationality of EIM parameters to evaluate muscle fatigue.The specific contents are arranged as follows:Firstly,a three-dimensional arm finite element simulation model was constructed based on the physiological information features of the experimental object.On this basis,the optimizing electrode configuration method was further obtained through a finite element solution method.The results showed that the electrode configuration with size of 40 mm×10 mm and spacing distance of 12 mm-24 mm-12 mm was optimized.It provided optimization conditions for following in vivo experiments.Secondly,Based on the EIM principle,the muscle fatigue experimental research were performed on the arm under the optimal electrode configuration.The results showed that the EIM resistance parameters R decreased with the accumulation of fatigue under the isometric or the isotonic contraction.The heavier the muscle load was,the faster the R declined.Meanwhile,according to the measurement results,the evaluation scheme was proposed in this dissertation.When the R value of the experimental object falls within the range of 43±5? in the isometric contraction scene and falls within the range of 41±5? in the isotonic contraction,or when the decrease in resistance reaches 8?,the muscle is more likely to be in a state of fatigue.Finally,the EIM parameters R and sEMG of different shrinkage processes were compared and analyzed.The results showed that both the EIM resistance parameter R and frequency domain index MF of sEMG were all downward with the accumulation of fatigue under two contraction modes.In the isometric contraction mode of each muscle load level,the falling slope of R is close to 1/4 of the MF.Under the dynamic scenario,the falling speed of R is about 2/5 of the MF.It can be seen that there is a strong consistency between the decline of R and MF,indicating that EIM is feasible and reasonable as an evaluation index of muscle fatigue.In this dissertation,EIM is applied to the experimental study of evaluating muscle fatigue,and the comparison and analysis with the sEMG were conducted,which verified that EIM can be used as a new technique to evaluate the muscle fatigue and provide a technical support and theoretical guidance for the development of wearable equipment for evaluating muscle fatigue conditions.