Author: Jalilian H1, Zamanian Z2, Gorjizadeh O1, Riaei S1, Monazzam MR3, Abdoli-Eramaki M4
1Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran.
2Department of Occupational Health Engineering, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran. email@example.com.
3Department of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran.
4School of Occupational and Public Health, Ryerson University, Toronto, Canada.
Conference/Journal: Int J Occup Environ Med.
Date published: 2019 Oct
Other: Volume ID: 10 , Issue ID: 4 , Pages: 174-184 , Special Notes: doi: 10.15171/ijoem.2019.1688. , Word Count: 250
BACKGROUND: Whole-body vibration (WBV) and mental workload (MWL) are common stressors among drivers who attempt to control numerous variables while driving a car, bus, or train.
OBJECTIVE: To examine the individual and combined effects of the WBV and MWL on the autonomic nervous system.
METHODS: ECG of 24 healthy male students was recorded using NeXus-4 while performing two difficulty levels of a computerized dual task and when they were exposing to WBV (intensity 0.5 m/s2; frequency 3-20 Hz). Each condition was examined for 5 min individually and combined. Inter-beat intervals were extracted from ECG records. The time-domain and frequency-domain heart rate variability parameters were then extracted from the inter-beat intervals data.
RESULTS: A significant (p=0.008) increase was observed in the mean RR interval while the participants were exposed to WBV; there was a significant (p=0.02) reduction in the mean RR interval while the participants were performing the MWL. WBV (p=0.02) and MWL significantly (p<0.001) increased the standard deviation of normal-to-normal intervals with a moderate-to-large effect size. All active periods increased the low-frequency component and low-frequency/high-frequency ratio. However, only the WBV significantly increased the highfrequency component. A significant (p=0.01) interaction was observed between the WBV and MWL on low-frequency component and low-frequency/high-frequency ratio.
CONCLUSION: Exposure to WBV and MWL can dysregulate the autonomic nervous system. WBV stimulates both sympathetic and parasympathetic nervous system; MWL largely affects sympathetic nervous system. Both variables imbalance the sympatho-vagal control as well.
KEYWORDS: Autonomic nervous system; Heart rate; Mental processes; Vibration; Workload
PMID: 31586382 DOI: 10.15171/ijoem.2019.1688