Physiological-induced conductive response evaluation in specific muscle compartments under hybrid of electrical muscle stimulation and voluntary resistance training by electrical impedance tomography

Objective: The physiological-induced conductive response has been visualised for evaluation in specific muscle compartments under hybrid (hybridEMS) of electrical muscle stimulation (EMS) and voluntary resistance training (VRT) by electrical impedance tomography (EIT). Methods: In the experiments, tendency of conductivity distribution images σ over time was clearly detected for three specific muscle compartments, which are called AM1 compartment composed of biceps brachii muscle, AM2 compartment composed of triceps brachii muscle, and AM3 compartment composed of brachialis muscle, under three training modalities. Results: From the experimental results, the tendency of physiological-induced conductive response are increased in all three training modalities with increasing training time. Correspondingly, the spatial-mean conductivity <σ>AM1,AM2,AM3 increased with the conductance value G and extracellular water ratio β of right arm by bio-impedance analysis (BIA) method. In addition, hybridEMS has the greatest effect on physiological-induced conductive response in AM1, AM2, and AM3. Under hybridEMS, the spatial-mean conductivity increased from <σpre > AM1 = 0.154 to <σ23mins > AM1 = 0.810 in AM1 muscle compartment (n = 8, p < 0.001); <σpre > AM2 = 0.040 to <σ23mins > AM2 = 0.254 in AM2 muscle compartment (n = 8, p < 0.05); <σpre > AM3 = 0.078 to <σ23mins > AM3 = 0.497 in AM3 muscle compartment (n = 8, p < 0.05). Conclusion: The paired-samples t-test results of <σ>AM1,AM2,AM3 under all three training modalities suggest hybridEMS has the most efficient elicitation on physiological induced conductive response compared to VRT and EMS. The effect of EMS on deep muscle compartment (AM3) is slower compared to VRT and hybridEMS, with a significant difference after 15 min of training. Copyright © 2023 Sun, Darma, Sejati, Shirai, Narita and Takei.