Complex assessment of athletes’ operative status and its correction during competitions, based on the body impedance analysis

Background and Study Aim. The aim of this research was assessment and correction of highly skilled swimmers’ operative status during competitions. Material and Methods. The authors carried out complex assessment of 46 high-skilled swimmers during competition period. The body impedance analysis and functional status express diagnosis were conducted before and after competitions. Results. The components limiting the operational state of swimmers were determined: “component composition of the body” (44.83% of the total load), “functional” (19.97%). Correlation relationships were established between the main indicators that determine the level of the operational state of athletes. The multiple regression equation was calculated, which made it possible to determine the influence of individual significant parameters on the level of the operational state of athletes and the confidence interval. A group of athletes with operational status indicators below the confidence interval received sport supplementation. Conclusion. The main characteristics of the athletes’ operative status are cellular biomarker phase, fat free mass, extracellular water, intracellular water, strength index. These characteristics should be used in assessment of both operative status and complex functional diagnosis of highly-skilled swimmers during competitions.

Circuit Models of Bioelectric Impedance

Accurate information about fluid distribution in different compartments of the human body is very important in various areas of medicine like drug dosage, renal replacement therapy, nutritional support, coronary artery disease, colorectal cancer and HIV infection. The body impedance analysis method being simple, inexpensive, accurate and noninvasive is largely used to this end. Several models of the body impedance are presented in this chapter. The first is the Cole model, a linear, first-order RC circuit valid for a frequency range of two decades. Another model, developed by De Lorenzo, employs a fractional-order impedance whose parameters are identified using the frequency characteristics of the impedance module and can be used for a frequency range of three decades. In addition, two other models are presented, a ladder RC model valid for a frequency range of two decades and its extension to three decades, as well as a circuit containing multiple RC branches connected in parallel. These two models are obtained by approximating the measured body admittance modulus with a physically realizable circuit function followed by the circuit synthesis. The last model can be simplified, its simplest form being the Cole model. Allowing a better prediction of the intracellular and extracellular water volumes, this model can be viewed as an extension of the Cole model.

Common-Mode Noise Reduction in Noncontact Biopotential Acquisition Circuit Based on Imbalance Cancellation of Electrode-Body Impedance

Biopotential sensing technology with electrodes has a great future in medical treatment and human—machine interface, whereas comfort and longevity are two significant problems during usage. Noncontact electrode is a promising alternative to achieve more comfortable and long term biopotential signal recordings than contact electrode. However, it could pick up a significantly higher level of common-mode (CM) noise, which is hardly solved with passive filtering. The impedance imbalance at the electrode-body interface is a limiting factor of this problem, which reduces the common mode rejection ratio (CMRR) of the amplifier. In this work, we firstly present two novel CM noise reduction circuit designs. The circuit designs are based on electrode-body impedance imbalance cancellation. We perform circuit analysis and circuit simulations to explain the principles of the two circuits, both of which showed effectiveness in CM noise rejection. Secondly, we proposed a practical approach to detect and monitor the electrode-body impedance imbalance change. Compared with the conventional approach, it has certain advantages in interference immunity, and good linearity for capacitance. Lastly, we show experimental evaluation results on one of the designs we proposed. The results indicated the validity and feasibility of the approach.