Characteristics of basal heart rate during daily life: Influences of age, gender, and seasons

To examine whether heart rate variability (HRV) during daily life shows power law behavior independently of age and interindividual difference in the total power, log-log scaled coarse-graining spectra of the nonharmonic component of 24-h HRV were studied in 62 healthy men (age 21–79 yr). The spectra declined with increasing frequency in all subjects, but they appeared as broken lines slightly bending downward, particularly in young subjects with a large total power. Regression of the spectrum by a broken line with a single break point revealed that the spectral exponent (β) was greater in the region below than above the break point (1.63 ± 0.23 vs. 0.96 ± 0.21, P < 0.001). The break point frequency increased with age ( r = 0.51, P < 0.001) and β correlated with age negatively below the break point ( r = 0.39) and positively above the break point ( r = 0.70). The contribution to interindividual difference in total power was greater from the differences in the power spectral density at frequencies closer to both ends of the frequency axis and minimal from that at −3.25 log(Hz), suggesting hingelike movement of the spectral shape at this frequency with the difference in total power. These characteristics of the 24-h HRV spectrum were simulated by an artificial signal generated by adding two noises with different β values. Given that the power law assumption is fundamental to the analysis of dynamics through the log-log scaled spectrum, our observations are substantial for physiological and clinical studies of the heartbeat dynamic during daily life and suggest that the nonharmonic component of HRV in normal subjects during daily life may include at least two 1/ f β fluctuations that differ in dynamics and age dependency.

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Personal Adaptive Method to Assess Mental Tension during Daily Life Using Heart Rate Variability

Methods of Information in Medicine ◽

10.3414/me11-01-0027 ◽

2012 ◽

Vol 51 (01) ◽

pp. 39-44 ◽

Cited By ~ 11

Author(s):

K. Matsuoka ◽

K. Yoshino

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Linear Regression ◽

Multiple Linear Regression ◽

Test Data ◽

Daily Life ◽

Pearson Correlation ◽

Multiple Linear Regression Model ◽

Training Data ◽

Data Set

SummaryObjectives: The aim of this study is to present a method of assessing psychological tension that is optimized to every individual on the basis of the heart rate variability (HRV) data which, to eliminate the influence of the inter-individual variability, are measured in a long time period during daily life.Methods: HRV and body accelerations were recorded from nine normal subjects for two months of normal daily life. Fourteen HRV indices were calculated with the HRV data at 512 seconds prior to the time of every mental tension level report. Data to be analyzed were limited to those with body accelerations of 30 mG (0.294 m/s2) and lower. Further, the differences from the reference values in the same time zone were calculated with both the mental tension score (Δtension) and HRV index values (ΔHRVI). The multiple linear regression model that estimates Δtension from the scores for principal components of ΔHRVI were then constructed for each individual. The data were divided into training data set and test data set in accordance with the twofold cross validation method. Multiple linear regression coefficients were determined using the training data set, and with the optimized model its generalization capability was checked using the test data set.Results: The subjects’ mean Pearson correlation coefficient was 0.52 with the training data set and 0.40 with the test data set. The subjects’ mean coefficient of determination was 0.28 with the training data set and 0.11 with the test data set.Conclusion: We proposed a method of assessing psychological tension that is optimized to every individual based on HRV data measured over a long period of daily life.

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