Conductive Response Imaging in Thigh Muscle Compartments by Electrical Impedance Tomography for Efficient Bicycle...

The conductive response in thigh muscle compartments has been imaged by electrical impedance tomography (EIT) under bicycle-operation conditions and muscle-stimulation conditions to determine an efficient training strategy. EIT is already applied to evaluate the effectiveness of electrical muscle stimulation (EMS) on human muscle, and hybrid of EMS which combines EMS on biceps and voluntary resistance training simultaneously. In this study, we newly applied EIT to the thigh muscle compartments and imaged the conductive response under bicycle-operation conditions and muscle-stimulation conditions. The bicycle-operation conditions are high pedal rate in low torque (HPLT) and low pedal rate in high torque (LPHT). The muscle-stimulation conditions are bicycle condition and EMS-combined bicycle condition. As a result, EIT successfully imaged the conductive response in three muscle compartments which are T1 compartment (quadriceps), T2 compartment (hamstrings), and T3 compartment (other than the quadriceps and hamstrings). The spatial-mean conductivity changes $\Delta ⟨{\sigma }_P⟩$ (the power of bicycle training $P=103,152,or194\left[W\right]$ ) increased with increasing power $P$ of the bicycle training across all four conditions and in all muscle compartments ( $\beta =0.531,p<0.001$ ). The $\Delta ⟨{\sigma }_P⟩$ of HPLT tended to be larger than $\Delta ⟨{\sigma }_P⟩$ of LPHT ( $\beta =-35.52,p<0.001$ ). The $\Delta ⟨{\sigma }_P⟩$ of EMS-combined bicycle condition tended to be larger than $\Delta ⟨{\sigma }_P⟩$ of bicycle condition ( $\beta =12.85,p<0.05$ ). The key findings are that HPLT and EMS-combined bicycle condition are a more efficient bicycle training than LPHT and bicycle condition for increasing $\Delta ⟨{\sigma }_P⟩$ .