Fig. 3

Cardiac autonomic control before and after each condition (4 S: green circles; 6 S: orange triangles; 9 S: blue squares; CON: grey diamonds). (A) LnSDNN: logarithm of the standard deviation of the R-R interval; (B) LnRMSSD: Logarithm of the root mean square of successive differences between adjacent R-R intervals; (C) LnHF: logarithm of the high-frequency power of the R-R interval in absolute values; (D) SampEn: sample entropy. # Significantly higher values in the control session at that time point compared to all experimental conditions (p < 0.001 in all cases); * Significant difference at the specific time point between 4 S and 6 S (p < 0.05); @ Significant difference at the specific time point between 4 S and 9 S (p < 0.05).