Individual variation of heart rate variability in Japanese population.

Research Project

Project/Area Number	15370104
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	生理人類学
Research Institution	Ishikawa prefectural nursing university
Principal Investigator	KOBAYASHI Hiromitsu Ishikawa prefectural nursing university, Department of nursing, Associate professor, 看護学部, 助教授 (20225535)
Co-Investigator(Kenkyū-buntansha)	NAKAYAMA Eijyun Kitasato University, Department of nursing, Lecturer, 看護学部, 講師 (70326081)
Project Period (FY)	2003 – 2006
Project Status	Completed (Fiscal Year 2006)
Budget Amount *help	¥9,700,000 (Direct Cost: ¥9,700,000) Fiscal Year 2006: ¥1,600,000 (Direct Cost: ¥1,600,000) Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000) Fiscal Year 2004: ¥3,600,000 (Direct Cost: ¥3,600,000) Fiscal Year 2003: ¥3,200,000 (Direct Cost: ¥3,200,000)
Keywords	heart rate variability / HRV / low-frequency / high-frequency / autonomic nervous system / reproducibility / ICC / posture / 自立神経 / 交感神経 / 副交感神経 / LF
Research Abstract	Spectral components of heart rate variability (HRV) were repeatedly measured (4-8 measurements; mean: 6 measurements) in 75 healthy Japanese male subjects (age range:20-61) under two postural conditions (standing and supine). Low-frequency (LF) and high-frequency (HF) components and mean heart rate (HR) were analyzed with special reference to individual variations, which were classified into two types : inter-(interV) and intra-individual variations (intraV). The percent contributions and coefficients of variations were calculated for both interV and intraV. Percent contributions of intraV (intraV%) of HR with standing and supine postures were 15.8 and 12.9%, respectively. The intraV% of HF and LF on standing were 31.5 and 26.5%, while those in the supine posture were 27.8 and 35.5%, respectively. The coefficients of interV (interCV) and intraV (intraCV) were also calculated. The interCVs of HR,HF, and LF on standing were 14.9,41.4,nd 48.4%, while those in the supine posture registered 16.2,42.9,and 44.2%, respectively. The intraCVs of HR, HF, and LF on standing were 5.0, 19.7, and 21.2%, while those in the supine posture indicated 4.7, 20.1, and 23.0%, respectively. We also calculated the interV and intraV of logarithmic-transformed HRV indexes. The log-transformation remarkably diminished both variables: interCV and intraCV registered 14-16 and 6-7%, respectively. Although interV variations were considerabley large, intraV variations of HRV were negligibley small. The HRV indexes decreased with age, although HR remained unchanged. The coefficients of determination (r^2) were 14-34%. In the case of log-transformed HRV indexes, the coefficients of determination registered 9-15%, suggesting that 14-34% (raw) or 9-15% (log) of the observed interV may be due to variations in age.