Objectives This study aimed to clarify haemodynamic responses of different age groups to simulated long working hours.
Methods Men of three age groups participated in this study (16 in their 30s (mean 33.9±2.7 years old), 15 in their 40s (45.5±2.9) and 16 in their 50s (54.1±2.7)). All participants conducted 12 45-min personal computer-based tasks from 09:00 to 22:00. Nine 10-min to 15-min breaks between task periods, a 1-hour break at noon, and a 50-min break in the evening were provided. Haemodynamic responses were measured during task periods. All participants had normal resting systolic blood pressure (SBP <140 mm Hg) and diastolic blood pressure (DBP<90 mm Hg), which were measured before tasks started in the morning. Two-way repeated-measures analysis of variances and multiple comparisons (Bonferroni) were conducted.
Results No haemodynamic indices were significantly different among groups at baseline. Compared with baseline, SBP was almost unchanged for the 30s group but increased for the 40s and 50s groups during task periods. The 50s group showed higher SBP compared with the 30s group especially in the latter half of the working hours (p<0.05). In addition, the 50s group also showed higher total peripheral resistance (TPR) than the 30s group (p<0.1).
Conclusion The 50s group showed higher SBP and TPR responses than the 30s group, especially in the latter half of working hours. These results suggest that older workers might suffer more cardiovascular damage related to long working hours.
- long working hour
- haemodynamic response
- older worker
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Contributors XL designed the study, carried out statistical analyses and wrote the main text. FO wrote the programming of experimental tasks. XL, HI and FO performed the experiments. TM supervised the study and taking the research grant. All authors contributed to the final version of the manuscript.
Funding The experiment is funded by the Industrial Disease Clinical Research Grants from the Ministry of Health, Labour and Welfare, Government of Japan (150903-01).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval All participants signed a written informed consent before the experiment. This study was approved by the Research Ethics Committee of the National Institute of Occupational Safety and Health of Japan (H2713, H3014) and all methods were performed in accordance with the relevant guidelines and regulations.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available.
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