Why the study?
Cardiovascular self-organized criticality had recently been demonstrated, prompting the study of autonomic nervous system changes to better characterize heart rate variability self-organized criticality.
Do physical training and body position changes affect heart rate variability self-organized criticality (Zipf's law distribution of bradycardias) in professional soccer players?
Do physical training and body position changes affect heart rate variability self-organized criticality (Zipf's law distribution of bradycardias) in professional soccer players?
Heart rate variability exhibits self-organized criticality following Zipf's law, which is strongly linked to autonomic standing adjustments but can be disrupted by physical training.
Answers are grounded in this paper and cite their sources.
May inform autonomic HRV assessment in athletes; leaves open whether position or training alters Zipf criticality clinically.
Cardiovascular self-organized criticality has recently been demonstrated. We studied a model of autonomic nervous system changes to better characterize heart rate variability self-organized criticality. The model included short and long-term autonomic changes associated with body position and physical training, respectively. Twelve professional soccer players took part in a 5-week training session divided into "Warm-up", "Intensive", and "Tapering" periods. A stand test was carried out at the beginning and end of each period. Heart rate variability was recorded beat by beat (Polar Team 2). Bradycardias, defined as successive heart rates with a decreasing value, were counted according to their length in number of heartbeat intervals. We checked whether bradycardias were distributed according to Zipf's law, a feature of self-organized criticality. Zipf's law draws a straight line when the rank of occurrence is plotted against the frequency of occurrence in a log-log graph. Bradycardias were distributed according to Zipf's law, regardless of body position or training. Bradycardias were much longer in the standing position than the supine position and Zipf's law was broken after a delay of four heartbeat intervals. Zipf's law could also be broken in some subjects with curved long bradycardia distributions by training. Zipf's law confirms the self-organized nature of heart rate variability and is strongly linked to autonomic standing adjustment. However, Zipf's law could be broken, the significance of which remains unclear.
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Fortrat et al. (2023) studied this question.
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