Autonomic Nervous System Influences on Cardiovascular Self-Organized Criticality

Area of Science:

• Physiology
• Complex Systems Science
• Cardiovascular Dynamics

Background:

• Cardiovascular self-organized criticality (SOC) is a recently identified phenomenon.
• The autonomic nervous system (ANS) plays a crucial role in regulating heart rate variability (HRV).
• Understanding HRV SOC can provide insights into ANS function and cardiovascular health.

Purpose of the Study:

• To model and characterize heart rate variability self-organized criticality.
• To investigate the influence of autonomic nervous system changes on HRV SOC.
• To examine the effects of body position and physical training on HRV SOC.

Main Methods:

• A computational model of ANS changes was developed.
• Twelve professional soccer players underwent a 5-week training program.
• Heart rate variability was recorded using beat-by-beat measurements during stand tests.
• Bradycardias were analyzed for adherence to Zipf's law, a characteristic of SOC.

Main Results:

• Bradycardias followed Zipf's law, indicating SOC, irrespective of body position or training status.
• Bradycardias were significantly longer in the standing position compared to the supine position.
• Zipf's law adherence was disrupted after four heartbeat intervals in the standing position.
• Physical training could alter Zipf's law distribution in some individuals.
• Zipf's law adherence was broken in some subjects by training.

Conclusions:

• HRV exhibits self-organized criticality, confirming its complex, emergent nature.
• Zipf's law adherence in HRV is strongly associated with autonomic adjustments during postural changes (standing).
• Deviations from Zipf's law, influenced by training and body position, warrant further investigation into their physiological significance.