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J Occup Health year 2002 volume 44 number 4 page 214 - 220
Classification Original
Title Blood Pressure and Heart Rate Variability in Taxi Drivers on Long Duty Schedules
Author Fumio KOBAYASHI1, Takemasa WATANABE2, Misuzu WATANABE1, Yasuhiro AKAMATSU1, Teruyuki TOMITA1, Taisuke NAKANE1, Hikari FURUI3, Kiyomi TAKEUCHI1, Akiyoshi OKADA4, Rumi OHASHI5 and Junichiro HAYANO6
Organization 1Department of Health and Psychosocial Medicine, Aichi Medical University School of Medicine,
2Department of Hygiene and Public Health, Osaka Medical College,
3Department of Psychology and Communication, Aichi Shukutoku University Faculty of Communication Studies,
4Health Promotion Center, Aichi University of Education,
5Department of Hygiene, Fujita Health University School of Medicine and
6The Third Department of Internal Medicine, Nagoya City University Medical School, Japan
Keywords Driver, Blood pressure, Heart rate variability, Long work hour
Correspondence F. Kobayashi, Department of Health and Psychosocial Medicine, Aichi Medical University School of Medicine, Nagakute-cho, Aichi 480-1195, Japan
Abstract Blood Pressure and Heart Rate Variability in Taxi Drivers on Long Duty Schedules: Fumio KOBAYASHI, et al. Department of Health and Psychosocial Medicine, Aichi Medical University School of Medicine-Objective-To clarify the mechanisms of excessive risk of cardiovascular disease among taxi drivers, the effects of taxi driving with long work hours on taxi drivers' blood pressure and heart rate variability were examined. Methods-We measured the physical activity level, ambulatory blood pressure, and Holter ECG in 34 healthy middle-aged male taxi drivers over one work day and the two following non-work days. The subjects worked for a 24-h period starting at 07:00, then rested from work for 48 h. Ambulatory blood pressure was recorded automatically at 30-min intervals over the 72-h period. Holter ECG records were also kept for the 72 h, and temporal changes in the R-R interval were analyzed by the complex demodulation method (CDM). The amplitude of the high frequency (HF) components (central frequency 0.30 Hz), and the ratio of low-frequency components (central frequency 0.09 Hz) to high-frequency components (L/H) was calculated. Results-Blood pressure during the work day was significantly higher than that during the non-work days, with a stronger effect in the hypertensive subjects. There were no significant overall differences in heart rate variability between the work day and the non-work days, but the temporal patterns of HF and L/H on the work day revealed a potent effect of reversed-phased circadian rhythm for work at night. Conclusions-Long duty taxi driving raises blood pressure and may increase cardiovascular risk as a result. The conflict between the circadian rhythms of autonomic nervous activity and work activity at night may also result in increased risk.