Editorial: New perspectives and insights on heart rate variability in exercise and sports

1 Editorial on the Research Topic 17 rate variability (HRV) has increasingly gained recognition in recent years as a significant 18 indicator of both mental and physical health, particularly in response to acute or chronic stressors. 19 During the acute phase, the variability in the elapsed time between successive heartbeats (the RR-20 interval) tends to decrease due to heightened sympathetic nervous system activation during exercise 21 (Bruce et al., 1963;Michael et al., 2017). Once exercise stops, this neural activation subsides, leading 22 to increased RR-interval variability associated with the reactivation of the vagus nerve 23 (parasympathetic system). Conversely, chronic HRV assessments performed without physical stimuli 24 provide insights into the overall balance of the autonomic nervous system (ANS).