• Science of Emotion and Sensibility
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• v.4 no.1
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• pp.1-5
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• 2001

The evaluation of mental workload is measured by subjective ratings, physiological signals. It takes long time to analysis the measured signals and is very tedious and time-consumming work. Therefore, to evaluate the affect of workload effectively, real-time measurement system is required. In this paper, real-time mental workload measurement system using cardiac autonomic indiced which reflect well the mental workload was developed and evaluated. Analyzed indices were HR, IBI, Lorentz plot, CSI, CVI, and LF/HF ratio of heart rate variability. The system was applied to evaluate the affect of arithmetic task and showed good results. This system was consisted of ECG amplifier, A/D converter, and personal computer, and algorithm was implemented using LabVIEW.

• Journal of Korean Academy of Nursing
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• v.41 no.6
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• pp.788-794
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• 2011

Purpose: Reduced heart rate variability significantly increases cardiovascular mortality. Metabolic syndrome increases the cardiac autonomic dysfunction. Recently, increasing cardiovascular mortality has been reported in patients with schizophrenia. This study was done to compare heart rate variability between adults with and without schizophrenia and to compare the relationship of heart rate variability to metabolic syndrome in hospitalized patients with schizophrenia. Methods: This was a descriptive and correlational study in which 719 adults without schizophrenia and 308 adults with schizophrenia took part between May and June 2008. We measured the following: five-minute heart rate variability; high-frequency, low-frequency, the ratio of low-frequency to high-frequency, and the Standard Deviation of all the normal RR intervals. Data was also collected on metabolic syndrome, abdominal obesity, triglycerides, HDL cholesterol, blood pressure and fasting glucose. Results: The Standard Deviation of all the normal RR intervals values of heart rate variability indices were $1.53{\pm}0.18$. The low-frequency and high-frequency values of heart rate variability indices were significantly higher in hospitalized patients with schizophrenia ($3.89{\pm}1.36$; $3.80{\pm}1.20$) than those in the healthy participants ($2.20{\pm}0.46$; $2.10{\pm}0.46$). There were no significant differences between the schizophrenic patients with and without metabolic syndrome. Conclusion: The results of this study indicate that schizophrenia patients have significantly lower cardiac autonomic control, but they have significantly higher low-frequency and high-frequency values than those of healthy adults. Use of antipsychotic drug may affect the autonomic nervous system in schizophrenic patients. Metabolic syndrome was not associated with cardiac autonomic control in schizophrenia patients.

• Journal of Life Science
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• v.28 no.5
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• pp.587-596
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• 2018

This study aims to observe changes in heart-rate variability (HRV) indices induced by e-cigarette and conventional-cigarette smoking and to compare the differences in acute cardiac autonomic regulation. All participants (n=41) were exposed to both e-cigarette smoke (ES) and conventional cigarette smoke (CS) in a randomized crossover trial. HRV analysis was performed during each smoking session based on a recorded r-r interval 10 minutes before smoking and at specified recovery periods (REC1, 0-5 min; REC2, 5-10 min; REC3, 10-15 min; REC4, 15-20 min; REC5, 20-25 min; and REC6, 25-30 min). ES led to a significantly increased cardiac sympathetic index (LF/HF ratio) compared with the baseline, and it shifted the sympathovagal balance toward sympathetic predominance, including reduction in the complexity of the interbeat interval (SampEn). In REC1 after ES, only decreases of parasympathetic indices such as rMSSD, pNN50, HF, and SD1 were indicated. CS sessions produced not only an increased LF/HF ratio during smoking and recovery periods (REC1 and REC4) but also enhanced sympathetic predominance on autonomic balance during smoking and recovery periods (REC1, REC2, and REC4). In the CS trials, parasympathetic indices of time and non-linear analysis (rMSSD, pNN50, and SD1) were decreased during smoking and in REC1 to REC5. SampEn was also reduced during smoking and REC1 to REC4. Acute sympathoexcitatory effects induced by e-cigarette use produced statistically significant results. Parasympathetic withdrawal after smoking suggests that e-cigarettes may cause increased cardiovascular risk.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.11a
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• pp.91-95
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• 2001

In this study, we estimated the behavior of the diversity of physiological responses under varied physical environmental factors by measuring variations of heart rate variability (HRV), an index of activity of cardiac autonomic control. Seven healthy young male adults consented and participated in the study. The environmental conditions consisted of thermal, lighting, and acoustic conditions. Two components of HRV were measured. one was the low frequency (LF) component of HRV, which provided a quantitative index of the sympathetic and parasympathetic (vagal) activities controlling the heart rate (HR). The other component measured was the high frequency (HF) component, which provided an index of the vagal tone. The percent contribution of physical environmental factors to the variations in HRV indices were calculated by ANOVA. The contribution of physical environmental factors to the variations in HR was higher than the contribution of HF and LF. However, the contribution of these factors was lower than the contribution related with individual difference in all indices. This result showed that the individual diversity of physiological responses is not a negligible quantity.

• Journal of the Korean Applied Science and Technology
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• v.36 no.1
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• pp.142-152
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• 2019

This study aimed to explore the association between obesity index and heart rate variability (HRV) in college-aged male smokers. A total of 85 male college students (> 10 cigarettes per day for at least 3 years) were participated in this study. According to a standardized protocol, body mass index (BMI), percent body fat (%BF), waist circumference (WC), and waist-to-hip ratio (WHR) were taken as obesity indices. Resting r-r interval was monitored for HRV analysis as an indicator of cardiac autonomic regulation. Compared with low WHR subjects, high WHR subjects had significantly lower values of rMSSD, pNN50, HF, and SD1, suggesting decreased parasympathetic activity. No such differences in LF/HF ratio were found between the WHR-based subgroups. Bivariate correlation analysis showed that obesity indices of WC, WHR, and %BF were significantly associated with rMSSD, pNN50, HF, and SD1, with a tendency for correlation coefficient to be higher with WHR than with WC or %BF. No significant association was found between BMI and HRV parameters indicative of parasympathetic activity. This study suggest that central obesity is significantly associated with decrease in parasympathetic activation, independent of BMI as an indicator of obesity, in male college smokers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.1050-1056
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• 2009

Heart Rate Variability(HRV) is a parameter that represents monitoring variability of time intervals between R-peak in electrocardiography. HRV serves to various applications, such as indices of autonomic functions, prediction of cardiac sudden death, assessment of stress and emotional, etc. However, as measuring R-peak in ECG needs at least 3-electrodes, and it is inconvenient for end users. In this paper, we suggested the modified laplacian electrodes for measuring HRV at one-point, which are producted by MEMS fabrication and have the two circular electrodes on the pad. For optimal position and direction, we performed an experiment that compared with pearson correlation coefficient and the amplitude of signals, between standard lead II and proposed electrodes. We analyzed the HRV parameters, such as standard deviation of the NN interval(SDNN), high frequency(HF), low frequency(LF), LF/HF ratio. The result showed that the average correlation coefficient and amplitude are 0.967 and 0.685 mVpp at the position 2. The coeffiecient correlation between the standard HRV and proposed electrode-HRV is 0.999

• Korean Journal of Biological Psychiatry
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• v.15 no.3
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• pp.186-193
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• 2008

Objectives : The authors tried to investigate the characteristics of Heart Rate Variability(HRV) among the subjects with metabolic syndrome for testing the possibility of clinical application of HRV in evaluating metabolic syndrome. Methods : We examined the difference of the means of HRV between 122 subjects of metabolic syndrome and 1057 healthy controls using T-test, and the change of means in HRV according to increasing risk factors of metabolic syndrome. Using multiple regression analysis, we examined the association of HRV with the risk factors of metabolic syndrome. Results : The HRV indices including SDNN(Standard Deviation of all normal NN intervals), RMSSD(the square Root of the Mean Squared Differences of successive all normal NN interval), TP(Total Power), LF(Low Freuency), and HF(High Frequency) were significantly lower in the metabolic syndrome group than in the normal control group, and the means of all HRV indices except LF/HF were decreased consistently according to increasing risk factors of metabolic syndrome. The fasting glucose, triglyceride, and waist circumference were dependent factors that contributed significantly to the change of HRV. Conclusion : These findings suggest metabolic syndrome adversely affects cardiac autonomic system and HRV could be a useful method for evaluating metabolic syndrome.

• Nutrition Research and Practice
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• v.14 no.6
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• pp.606-620
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• 2020

BACKGROUND/OBJECTIVES: Although some juices affect subjective sleep quality, there is a lack of information on the effect of a specific juice on objective sleep quality and heart rate variability (HRV) during sleep; thus the present study investigated whether a blended juice made from natural extracts influenced sleep quality and HRV during sleep in adults with disturbed sleep. SUBJECTS/METHODS: A randomized, crossover study was conducted on twenty-five adults (15/10, female/male) complaining of difficulty initiating or maintaining nighttime sleep (Pittsburgh sleep quality index [PSQI] ≥ 5). During feeding sessions (FS), subjects received sleep-inducing juice made of natural ingredients (250 mL/trial) twice a day for 8 weeks or non-FS (N-FS) for 8 weeks while maintaining normal activities. Sleep quality and parameters were recorded via wearable actigraph for 7 consecutive days, and PSQI scores were assessed before and after the intervention. HRV was also monitored at rest and during sleep. RESULTS: After receiving the sleep-inducing juice intervention (FS), PSQI scores were significantly decreased (P < 0.001) and correlated with a significant decline in fatigue severity scale and visual analogue scale levels (P < 0.05; both). HRV indices of vagal activity were significantly improved during FS (P < 0.05), and no significant differences in N-FS were observed. Sleep efficiency and total sleep time increased significantly (P < 0.05) and sleep latency, total counts, sleep fragmentation index, and movement index, decreased significantly (P < 0.05, all 4) during FS, with no significant differences-observed during N-FS. CONCLUSIONS: This study results demonstrated that an 8-week course of sleep-inducing juice has led to improve sleep quality, suggesting an enhanced cardiac vagal tone during sleep. Thus, it could be a well-tolerated option for adults with disturbed sleep.

• Journal of Life Science
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• v.18 no.3
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• pp.291-297
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• 2008

We investigated whether 1) the combined capsaicin (75 mg), sesamin (30 mg), and L-carnitine (900 mg) (CCSC) ingestion enhances autonomic nervous system (ANS) activities including thermogenic sympathetic activity as energy metabolic modulator, 2) ${\beta}_3-AR$ polymorphism of each subject influences with ANS activity. Seven healthy males $(22.0{\pm}0.5\;yr)$ volunteered for this study. The cardiac autonomic nervous activities evaluated by means of heart rate variability of power spectral analysis were continuously measured during 5 min every 30 min for total 120 min resting condition with CCSC or placebo oral administration chosen at random. The results indicated that, there are not $Arp/Arg^{64}$ variants of the ${\beta}_3-AR$ genotypes in our subjects. There were not also significant differences in heart rate during rest between both trials. The difference of ANS activity did not reach the statistical significance between both trials. However, the significant improvement showed TOTAL power, HF component, and the indices of SNS and PNS activities before and at 30 min after CCSC ingestion (p<0.05, respectively). In conclusions, although each component of combined CCSC is associated with lipolysis and/or fat oxidation, the combined CCSC consumption is not influenced in stimulation of thermogenic sympathetic activity as modulator of energy metabolism. In rather, our results suggested that CCSC ingestion improves the balance of both SNS and PNS activities. Therefore, it will be considered many combined nutrient components for ergogenic and/or lipolysis effects as well as genetic variants affecting ANS activity in further studies.