Electrical Characteristics Response Study of Blood Flow Velocity and Blood Lactate Concentration Based on Electrical Impedance Tomography
Lactic acid produced by muscles during exercise training is transported to the liver for metabolism through the bloodstream.In this process,the lactate acid level increases with the increase of exercise intensity,and the concentration of lactate acid in interstitial matrix of muscle tissues increases subsequently,leading to muscle fatigue.Transcutaneous electrical nerve stimulation(TENS)is a widely used medical method for muscle relaxation and improving peripheral blood circulation.To monitor the potential of TENS to alleviate muscle fatigue,this study adopted electrical impedance tomography(EIT)method to visualize the alleviating effect of TENS on muscle fatigue by detecting the tissue electrical characteristics response caused by the changes in blood lactate concentration,a biomarker of muscle fatigue.An experimental platform was thus constructed to mimic the changes of blood lactate concentration(Cbl)in the muscle tissue model,and to measure the trend of the spatial-mean conductivity((σ))in the mimic model during the Cbl change.The blood flow velocity was closely related to the metabolic rate of the lactate in the blood.TENS could speed up blood flow and effectively reduced the lactate accumulation in muscle tissue.However,too fast blood flow velocity was prone to cause secondary ventricular fibrillation disease,which threatened the safety of human life.To avoid this threat,a real-time blood flow velocity mimic platform was developed in this study to monitor the(σ)changes caused by the changes in blood flow velocity(vph)in the vicinity of mimic blood vessels.The correlations between Cbl vs(σ),and vph vs(σ)in the mimic muscle tissue were verified by Pearson test.Pearson correlation analysis results showed a positive correlation between Cbl and(σ)(r=0.9113,p<0.05),and betweenvph and(σ)(r=0.9782,p<0.001).The approach presented here quantitatively assessed the potential of TENS stimulation-induced changes in lactate concentration and blood flow velocity for alleviating muscle fatigue through(σ).