Sex and age differences in the association between heart rate variability and cardiac chronotropy: A replication‐extension study

Figures

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  FIGURE 1. Conceptual moderation models of the current investigation. cv, coefficient of variation; HRT, hormone replacement therapy; IBI, inter‐beat‐interval; RMSSD, root mean square of successive in beat‐to‐beat interval differences.

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  FIGURE 2. Sex differences in the association between vagally‐mediated heart rate variability and cardiac chronotropy in younger (top panels) and older (bottom panels) individuals. (a) and (c) show scatterplots of lnRMSSD and IBI in men and women of both age groups. (b) and (d) represent the prediction of IBI values in men and women of both age groups at low, mean, and high lnRMSSD values. Higher and lower estimates of lnRMSSD were derived from ±1SD from the mean. IBI, inter‐beat intervals; LnRMSSD, natural log‐transformed root mean square of successive beat‐to‐beat interval differences.

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  FIGURE 3. Age differences in the association between vagally‐mediated heart rate variability and cardiac chronotropy in women (top panels) and men (bottom panels) individuals. (a) and (c) show scatterplots of lnRMSSD and IBI in younger and older individuals of both sex groups. (b) and (d) represent the prediction of IBI values in younger and older individuals of both sex groups at low, mean, and high lnRMSSD values. Higher and lower estimates of lnRMSSD were derived from ±1SD from the mean. IBI, inter‐beat intervals; LnRMSSD, natural log‐transformed root mean square of successive beat‐to‐beat interval differences.

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  FIGURE 4. The top panels represent box and whisker plots for IBI (a) and lnRMSSD (b) values in older women with (n = 17) or without (n = 59) HRT (n = 59). The boxes are determined by the 25th and 75th percentiles. The whiskers are determined by 1.5 interquartile range. The bottom panels show a scatterplot of lnRMSSD and IBI values (c) and the prediction of IBI values at low, mean, and high lnRMSSD values (d) in older women with or without HRT. Higher and lower estimates of lnRMSSD were derived from ±1SD from the mean. HRT, hormone replacement therapy; IBI, inter‐beat intervals; lnRMSSD, natural log‐transformed root mean square of successive beat‐to‐beat interval differences.