Non-linear dynamics of heart rate variability during incremental cycling exercise
Thomas Gronwald1, Olaf Hoos2, Sebastian Ludyga3
1a MSH Medical School Hamburg , University of Applied Sciences and Medical University , Hamburg , Germany.
Research in Sports Medicine (Print)
|July 25, 2018
Summary
This study shows that high exercise intensity alters heart rate variability (HRV) dynamics. Autonomic nervous system control of heart rate shifts from complex to non-autonomic mechanisms during intense exercise.
Area of Science:
- Cardiovascular Physiology
- Exercise Science
- Autonomic Neuroscience
Background:
- Heart rate variability (HRV) is crucial for understanding autonomic nervous system (ANS) function.
- Complex models of cardiovascular regulation and exercise fatigue increasingly utilize HRV.
- Detrended fluctuation analysis (DFA) is a key method for assessing HRV complexity.
Purpose of the Study:
- To investigate the impact of varying exercise intensities on HRV complexity and dynamics.
- To analyze changes in heart rate correlation properties using DFA during graded exercise.
- To determine how exercise intensity influences the self-organized regulation of heart rate.
Main Methods:
- Sixteen cyclists underwent a graded exercise test on a bicycle ergometer.
- HRV time-domain measures were analyzed.
- Fractal correlation properties of HRV were assessed using the short-term scaling exponent alpha1 of DFA.
Main Results:
- Amplitude and complexity of HRV parameters significantly decreased with increasing exercise intensity.
- DFA-alpha1 increased from rest to low exercise intensity.
- DFA-alpha1 exhibited a near-linear decline from higher intensities to exhaustion.
Conclusions:
- Exercise intensity significantly alters HRV, indicating a shift in cardiovascular regulation.
- At high intensities, the complex autonomic control of heart rate transitions to non-autonomic mechanisms.
- These findings highlight a breakdown in ANS interaction during strenuous exercise, impacting heart rate regulation.
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