Non-linear dynamics of heart rate variability in athletes: effect of training

Abstract

Only few studies on heart rate variability (HRV) in athletes have been performed so far. Moreover most of the data were obtained from time or frequency analysis. The aim of the present work was to use methods of nonlinear dynamics to study heart rate variability in a young population consisting of athletes and a sedentary group, used as controls. ECG episodes lasting 10 min were recorded digitally in supine position in a group of 34 young subjects. Spectral analysis was performed with Fast Fourier transform (FFT). Following non-linear methods were computed: fractal dimension),1/f slope, approximate entropy (ApEn) and Lyapunov exponent. Major difference between controls and aerobic athletes was in resting heart rate. ApEn correlated well with power spectral density. Aerobic athletes showed a difference with controls in ApEn and Lyapunov exponent. Results indicate a possible relation of non-linear indices and autonomic regulation of cardiovascular function.

Heart Rate Variability Indexes as a Marker of Chronic Adaptation in Athletes: A Systematic Review

“…Only one protocol with controlled breathing showed a negative ES for the normalized HF, which was inconsistent with the same condition in the other study (Table ) . Both studies with rugby athletes showed a negative ES for HF in logarithmic scale . The ES showed that the protocol, the modalities of sport and the unit of measure both appeared to contribute for the controversial results found in the literature, especially in the frequency domain analyses.…”

“…From seven protocols using the low and high absolute spectral power, only one showed a moderate positive ES (Table ) . Contrarily, five protocols using the logarithmic transformation to calculate the power in LF showed large positive ES (Table ) . Considering normalized LF, two protocols with free breathing found a consistent negative ES, whilst two protocols with controlled breathing showed ESs with opposite signals (Table ) …”

“…The total number of athletes was about 333 males and females, aged between 17 and 40 years, who practiced different sports (running, cycling, swimming, canoeing, athletics, skating, volleyball, football, basketball, rugby, and triathlon). For the sample characterization, seven studies used the VO 2 as a physiological measure, seven studies reported the length of time that the athletes had practiced the sport (over 2 years), and eight studies selected athletes participating in national, regional, or international competitions . No study reported the athlete's training phase during the course of the experiment.…”

“…The provided mean and standard deviation values from 14 articles were included in the quantitative analyses of the Cohen's ES, whose large and moderate values were showed in time (Table ) and frequency domain (Table ).…”

“…The HRV data were provided by articles or by e‐mail through contact with the authors. Missing values are due to graphic representations in the articles and mismatched data received by e‐mail .…”