Fig. 2From: Changes in heart rate variability with respect to exercise intensity and time during treadmill runningLomb-Scargle PSD estimates for a single participant for the three time windows \(w_1\), \(w_2\) and \(w_3\) at moderate (a) and vigorous (b) intensities. The vertical dashed lines delineate the ultra-low frequency (ULF), very-low frequency (VLF) and low-frequency bandsBack to article page