engleski

Measurement of lower-leg muscle impedance in national taekwondo team and students non-athletes

Electrical impedance is a complex measure of resistance, represented not only with relative magnitudes of voltage and current, but also with the phase angle. The phase angle represents the value of phase shift between the voltage and the current. We have measured the electrical impedance of musculus gastrocnemius for two different groups of examinees. The first group was Croatian taekwondo team with both males and females, and the other was a group of students matched on age and sex. The magnitude (|Z|) and phase (φ ) of impedance were measured from 100 Hz do 1 MHz, by the HP 4284A impedance meter, using the Ag-AgCl ECG self adhesive electrodes. To achieve easier control of the instrument parameters, we have developed a computer application using the Microsoft .NET 2.0 framework. The results show the difference of mean value of |Z| between taekwondo athletes and students at high frequencies. We have ignored the impedance at lower frequencies because it is dominantly affected by the electrode and skin impedance and does not reflect the difference of the impedance of muscles. We have found that the mean value of |Z| is lower for males and higher for females in both tested groups. We have compared the differences that we noticed, with the results of conductivity and permittivity measurements of Gabriel and co-workers. The measured differences in impedance spectra indicate the structural difference of the leg tissue between the groups. We think that the higher mean value of |Z| in females is probably because of genetically conditioned enlarged quantity of subdermal adipose tissue. The observed difference in impedance between male taekwondo team and the group of male students are most likely related to the larger muscle mass in members of the taekwondo team.

electrical bioimpedance; muscle impedance; in vivo measurement; taekwondo athletes; instrument control

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