HEART RATE VARIABILITY
Sayers, B. McA. (1973). Analysis of heart rate variability. Ergonomics, 16, 17-32.
Several factors produce inconsistent heart beat cycles.
- Under resting conditions, the cardiac interbeat signal fluctuates probably because of thermal and blood pressure control systems.
- Respiration also causes cycle fluctuations.
- Thermal and blood pressure controls as well as respiration account for 75-90% of the variation.
- In mental work, it is the change in respiratory pattern and not rate, that causes the HR characteristics.
- HR is not a valuable parameter for exploring the workload response in a normal individual.
A respiratory pattern is the duration, depth, and detailed shape of the intrapleural pressure wave form. Such a spectrum is revealed over a 60-120 sec period.
HR may be more stable at higher rates.
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