Cardiac autonomic disturbance following sprint-interval exercise in untrained young males: Does exercise volume matter?

Abstract

Objectives: This study examined the influences of the volume of all-out sprint-interval exercise (SIE) on acute post-exercise heart rate variability (HRV) recovery. Methods: HRV recovery following a session of (i) 2 × 30-s SIE (SIE2), (ii) 4 × 30-s SIE (SIE4), and (iii) non-exercising control (CON) were compared in 15 untrained young males. Time domain [standard deviation of normal-to-normal intervals, root mean square of successive R-R differences] and frequency domain [low frequency (0.04–0.14 Hz), high frequency (0.15–0.40 Hz)] measures of HRV were assessed every 20 min for 140 min after the exercise, and every hour during the first 4 h of actual sleep time at immediate night. All trials were scheduled at 19:00. Results: In comparison to CON, both SIE2 and SIE4 attenuated the HRV markedly (p 0.05). Nevertheless, the post-exercise HRV restoration in SIE2 appeared to be faster than that in SIE4. Regardless, nocturnal HRV measured within 10 h following the exercise was not different among the SIE and CON trials (p > 0.05). Conclusion: Such findings suggest that the exercise volume of the SIE protocol may be a factor affecting the rate of removal of the cardiac autonomic disturbance following the exercise. In addition, rest for ∼10 h following either session of the SIE protocol appears to be appropriate for the cardiovascular system to recover.

Keywords

• Sprint-interval training
• Heart rate variability
• Cardiovascular system
• Cardiac parasympathetic activity
• Cardiac health