Measuring effects of height on the autonomic nervous system in middle-aged adolescents using the very low frequency band of heart rate variability

Abstract

Previous studies have revealed the association between falling accidents and stress, measured via heart rate variability (HRV). However, none have studied this association using the very low frequency (VLF) band of HRV in adolescent populations. This study aimed to fill this gap by recruiting 90 adolescents to perform a light physical task at varying heights. Heart rates were used to calculate short-term HRV. The results showed a positive correlation between VLF bands and parasympathetic indices and a negative correlation with sympathetic indices, demonstrating the balancing effects of the autonomic modulation associated with height. The lowest VLF bands were obtained as 79.25 ms² at 10 m (p < 0.001) and 62.87 ms² at 9 m (p < 0.001) for the experienced and non-experienced male groups, respectively, and 28.09 ms² at 6 m (p = 0.001) for the female group. The results also suggested the need for a relatively lower height restriction for female adolescents than for males.

Practitioner summary: Increased working heights can cause stress, which leads to falling accidents. The very low frequency band was shown to be associated with parasympathetic and sympathetic indices. Furthermore, the results suggested that the height limit necessary for providing a safe working environment may be lower for female adolescents than for males.

Abbreviations: HRV: heart rate variability; VLF: very low frequency; ms2: absolute power; ANS: autonomic nervous system; PNS: parasympathetic nervous system; SNS: sympathetic nervous system; RR: intervals between two successive peaks of R waves; RMSSD: root mean square of successive RR interval differences; SD1: Poincaré plot index of standard deviation 1; SD2: Poincaré plot index of standard deviation 2; HF: high frequency; LF: low frequency; BMI: body mass index; ECG: electrocardiography; HR: heart rate; FFT: fast Fourier transformation; IQR: interquartile range; r: non-parametric partial correlation coefficient; η2: eta-squared; EM: experienced males; NM: non-experienced males; NF: non-experienced females; EEG: electroencephalogram

Keywords:

• Parasympathetic nervous system
• sympathetic nervous system
• working at height
• adolescent workers
• occupational safety

Author contributions

WC conceptualised the manuscript and analysed the data. WP wrote and revised all versions of the manuscripts. AW conducted the experiment and collected the data. The authors contributed equally to this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research is supported by Chulalongkorn University Ratchadapisek Somphot Fund for Postdoctoral Fellowship and for the Research Unit on Population, Family Dynamics, and Social Policy. AW is supported by the National Research Council of Thailand [NRCT: Grant no. 25/2561] and the Department of Labour Protection and Welfare, the Ministry of Labour, Thailand.