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Frequency characteristics of long-term heart rate variability during constant-routine protocol
Naoko Aoyagi1, Kyoko Ohashi, Yoshiharu Yamamoto
1Educational Physiology Laboratory, Graduate School of Education, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Summary
Behavioral factors like diet and activity significantly influence heart rate variability (HRV) over longer periods (>1 hour). However, HRV above this threshold appears independent of behavior, suggesting an intrinsic regulatory system.
Area of Science:
- Physiology
- Chronobiology
- Biomedical Engineering
Background:
- Long-term heart rate variability (HRV) is influenced by behavioral factors, but these effects are not fully understood.
- Physical activity, food intake, and circadian rhythms are key behavioral influences on physiological regulation.
Purpose of the Study:
- To investigate the impact of behavioral factors on long-term HRV.
- To differentiate between behavior-dependent and behavior-independent components of HRV.
Main Methods:
- Utilized a constant-routine protocol with simultaneous core body temperature (CBT) monitoring.
- Employed generic spectral analysis and coarse-graining spectral analysis on HRV data.
- Compared HRV during a 27-hour constant routine with a normal daily routine in healthy subjects.
Main Results:
- HRV exhibited similar power-law scaling above ~10(-3.5) Hz in both constant and daily routines.
- Below ~10(-3.5) Hz, HRV was significantly lower during the constant routine, indicating behavioral influence.
- Coarse-graining analysis removed meal-related artifacts and highlighted the ~10(-3.5) Hz crossover frequency.
- Core body temperature correction did not affect the observed results.
Conclusions:
- Behavioral factors significantly impact HRV below a frequency of ~10(-3.5) Hz (periods >1 hour).
- Above this crossover frequency, HRV appears independent of behavior, potentially reflecting intrinsic physiological regulation.
- The findings help distinguish between externally influenced and intrinsic components of heart rate variability.