MICROCOMPUTER SYSTEM (VariaCardio TF4) DESIGNED FOR THE DIAGNOSTICS OF HEART RATE VARIABILITY DURING HUMAN MOVEMENT
Keywords: spectral analysis, heart rate variability (HRV), autonomic nervous system (ANS), sport training, telemetric diagnostic system
AbstractINTRODUCTION: One of many possibilities of controlling the intensity of sport training and the responses of an athlete to an exercise load is through the regulation of heart rate (HR) values or the evaluation of heart rate variability (HRV). While the HR diagnostics can be realized with the help of several devices (e.g. SPORTESTER - POLAR ELEKTRO, Finland), the evaluation of HRV, using spectral analysis, is limited by the lack of diagnostic methods for sport practice and availability at an acceptable price. METHOD: Changes of autonomic nervous system (ANS) behavior was evaluated with the help of so-called "short-term" spectral analysis of HRV. This method supplies information on changing ANS activities (sympathetic and vagal subsystems) during the course of physical and psychological load. ANS evaluation was used by means of the telemetric computer-aided system (VariaCardio TF 4) to enable researchers to register the ECG signal, to evaluate the length of RR intervals accurate to 1 ms and to transfer the data with help of a miniature UHF transmitter, even during movement activities. A UHF receiver was connected to a standard serial COM ports of a microcomputer. The system involved software to calculate HRV parameters in time and frequency domains. RESULTS: Evaluation of ANS in the frequency domain is based on "short-term" spectral analysis of HRV (SAHRV) which enables evaluation of ANS effects on the heart rate in 1 to 15 defined load situations, each monitored for 300 seconds. The software procedure directs the course of examination, filtered artifacts and calculated SAHRV parameters according to a partially modified algorithm (CGSAcoarse- graining spectral analysis) (YAMAMOTO et al., 1991) assuring optimum suppression of the noise component of the analyzed signal. The results of SAHRV were POWER SPECTRAL DENSITY( SPECTRAL POWER in the frequency bands of 0.01-0.05 Hz (VLF), 0.05-0.15 Hz (LF), and 0.15-0.5 Hz (HF)( RELATIVE POWER( RATIO POWER( and others . CONCLUSIONS: Experiences with the application of the VariaCardio TF 4 system confirms that examination is not time consuming and the system is easy to use. The corrections in the regulation of the training process, resulting from the obtained data of the ANS examinations, can optimize the whole process and make it effective. REFERENCE: Yamamoto, Y., Hughson, R. L. (1991). Coarse-Graining Spectral Analysis: Next Method for Studying Heart Rate Variability. Journal of Applied Physiology, 71,1143-1150.
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