Different effects of inspiratory duration and expiratory duration on heart rate deceleration capacity and heart rate asymmetry

Yong-Ping Wang; Terry B J Kuo; Guo-Zhi Wang; Cheryl C H Yang

doi:10.1007/s00421-024-05433-2

Different effects of inspiratory duration and expiratory duration on heart rate deceleration capacity and heart rate asymmetry

Eur J Appl Physiol. 2024 Feb 29. doi: 10.1007/s00421-024-05433-2. Online ahead of print.

Authors

Yong-Ping Wang¹, Terry B J Kuo^{2

3

4

5

6}, Guo-Zhi Wang⁷, Cheryl C H Yang^{8

9

10

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Affiliations

¹ Department of Anesthesiology, National Taiwan University Hospital, Taipei, Taiwan.
² Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan.
³ Sleep Research Center and Institute of Brain Science, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Li-Nong St., Taipei, 11221, Taiwan.
⁴ Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan.
⁵ Department of Education and Research, Taipei City Hospital, Taipei, Taiwan.
⁶ Clinical Research Center, Taoyuan Psychiatric Center, Ministry of Health and Welfare, Taoyuan, Taiwan.
⁷ Department of Surgery, Chung Shan Medical University Hospital, Taichung, Taiwan.
⁸ Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan. cchyang@nycu.edu.tw.
⁹ Sleep Research Center and Institute of Brain Science, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Li-Nong St., Taipei, 11221, Taiwan. cchyang@nycu.edu.tw.
¹⁰ Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan. cchyang@nycu.edu.tw.
¹¹ Department of Education and Research, Taipei City Hospital, Taipei, Taiwan. cchyang@nycu.edu.tw.

PMID: 38421428
DOI: 10.1007/s00421-024-05433-2

Abstract

Purpose: Low values of heart rate deceleration capacity (DC) and heart rate asymmetry (HRA) are associated with cardiovascular risks. Slow respiration has been proven to enhance the magnitudes of these indexes, but individual inspiratory (T_I) and expiratory (T_E) durations were not controlled in most studies. This study aims to examine whether the effects of T_I and T_E on these indexes would be the same and, if not, how to adjust T_I and T_E to maximize the effect of slow respiration.

Methods: We evaluated 14 seated healthy young adults who randomly controlled their breathing to nine combinations of T_I and T_E, each chosen respectively from 2, 4, and 6 s. A 5-min R-R interval time series was obtained from each study period for further analysis.

Results: The magnitude of DC increased when T_I or T_E increased, while that of acceleration capacity (AC) remained almost unchanged by T_I. We further defined a new index as 100 × DC²/(DC² + AC²) and found it to be correlated with conventional Guzik's (r = 0.94) and Porta's (r = 0.99) indexes of HRA during different combinations of T_I and T_E. Increasing T_I and increasing T_E both enhanced the magnitudes of HRA indexes, with T_I taking effect when ≤ 4 s, and T_E taking effect when > 4 s. DC and HRA indexes were maximized with a T_I of 4 s and a T_E of 6 s.

Conclusion: We suggest that a T_I of 3-4 s with a T_E of 7-6 s is an appropriate standard for slow respiration.

Keywords: Acceleration; Deceleration; Expiration; Heart rate; Inspiration.

Abstract

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