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[This article belongs to Volume - 71, Issue - 2]
Published on : 2026-02-28 21:50:42
Article Code: AMJ-28-02-2026-12369
Title : Altitude-related variations in heart rate variability among native Japanese Alpine residents: A cross-sectional study
Author(s) : Yuki Tanaka, Kenji Yamamoto, Haruki Sato & Akiko Nakamura
Abstract :
Background & objectives: Living at high altitudes causes chronic exposure to hypoxia, which triggers various physiological and autonomic adaptations. While previous studies in Himalayan populations have demonstrated enhanced parasympathetic activity among high-altitude natives, the autonomic adaptations in Japanese Alpine populations remain poorly characterized. This study assessed the impact of altitude on cardiac autonomic activity through heart rate variability (HRV) analysis in healthy Japanese residents of the Japan Alps.
Methods: A cross-sectional study was conducted among the Japanese population residing at high, intermediate and low altitudes of Nagano and Yamanashi prefectures. Two areas from each altitude category were selected. Based on the population of the selected areas, the sample size was distributed using probability proportional to size sampling. Systematic random sampling was then used to select participants. For each participant, a 5-min ECG was recorded using lead II of a Power Lab system. HRV analysis was performed to derive time and frequency-domain indices from spectral analysis of successive R-R intervals.
Results: We found significantly lower values of time domain HRV indices including standard deviation of all normal-to-normal intervals (SDNN) and root mean square of successive differences between normal heartbeats (RMSSD) among the people residing at higher altitudes in the Japanese Alps. Conversely, the LF/HF ratio was significantly elevated in high-altitude residents, indicating sympathetic predominance.
Interpretation & conclusions: Residents living at high altitudes in the Japanese Alps exhibit reduced overall HRV and enhanced sympathetic cardiac activity compared to those residing at lower and intermediate elevations, reflecting a distinct adaptive response to chronic hypobaric hypoxia that differs from Himalayan high-altitude populations. These findings suggest that genetic background and altitude duration may influence autonomic adaptation patterns.