Figure 1From: Normative references of heart rate variability and salivary alpha-amylase in a healthy young male populationHistograms of the interindividual variation of heart period, log-transformed heart rate variability indices and time-domain heart rate variability indices. HRV indices included lnHF, lnLF and ln(LF/HF). Right-skewed distributions were observed for lnHF and the time-domain indices (SDNN and rMSSD).Back to article page