Electrical-tomographic imaging of physiological-induced conductive response in calf muscle compartments during voltage intensity change of electrical muscle stimulation ( <i>vic</i> -EMS)
Bo Sun, Panji Nursetia Darma, Tomoyuki Shirai, Kosei Narita, Masahiro Takei
Abstract
Abstract Objectives . The electrical-tomographic imaging has been achieved for exploring differential tendency of physiological-induced conductive response in calf muscle compartments during voltage intensity change of electrical muscle stimulation ( vic -EMS). Approach . In the experiments, the differential tendency of conductivity distribution images σ during vic -EMS were clearly imaged as three responsive muscle compartments, which are called M 1 compartment composed of gastrocnemius muscle, M 2 compartment composed of tibialis anterior, extensor digitorum longus, and peroneus longus muscles, and M 3 compartment composed of soleus muscle. Main results . The differential tendency of spatial-mean conductivity 〈 σ 〉 M 1 is the same as the differential tendency of venous blood flow velocity v bl and blood lactate concentration C bl during vic -EMS by the increased tendency of spatial-mean conductivity difference Δ〈 σ 〉 M 1 , venous blood flow velocity difference Δ v bl and blood lactate concentration difference Δ C bl . The 〈 σ 〉 M 1 is increased with the increase of voltage intensity from 〈 σ pre 〉 M 1 = 0.142 [-] to 〈 σ l 14 〉 M 1 = 0.442 [-] ( pre : pre-training, l 14: voltage level during vic -EMS l = 14) by Δ〈 σ l 14- pre 〉 M 1 = 204.2% ( n = 16, p < 0.01). Correspondingly, the v bl and C bl are increased with the increase of voltage intensity by Δv bl l 14- pre = 1480.5% ( n = 16, p < 0.01) and Δ C bl l 14- pre = 230.1% ( n = 16, p < 0.01) respectively. Significance : The reason for the differential tendency of increase in < σ > M 1 suggests an increase in muscle extracellular volumes during vic -EMS due to the co-effect of venous blood flow velocity and blood lactate metabolism. Based on the conductivity second-order difference images <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mfenced close="∣" open="" separators=""> <mml:mrow> <mml:mstyle displaystyle="false"> <mml:mfrac> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>∂</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msup> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="bold-italic">σ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>M</mml:mi> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mi>φ</mml:mi> </mml:mrow> </mml:msubsup> </mml:mrow> <mml:mrow> <mml:mi>∂</mml:mi> <mml:msup> <mml:mrow> <mml:mi>φ</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:mfrac> </mml:mstyle> <mml:mspace width=".25em"/> </mml:mrow> </mml:mfenced> </mml:mrow> <mml:mrow> <mml:mi>φ</mml:mi> </mml:mrow> </mml:msub> </mml:math> and spatial-mean conductivity second-order difference