Key result
Severe intensity interval training significantly reduced time domain indices of heart rate variability by 11-55% at 1 hour post-exercise compared to moderate intensity training (p<0.01).
Why the study?
Does severe intensity exercise compared to moderate intensity exercise affect heart rate variability in runners?
RCT (n=16)
Counterbalanced order
No
Does severe intensity exercise compared to moderate intensity exercise affect heart rate variability in runners?
p-value: p=<0.01
Severe exercise transiently reduces parasympathetic influence on the heart at 1 hour post-exercise in runners, with full recovery by 24 hours.
Severe training may transiently blunt post-exercise HRV in runners; hypothesis-generating and should not yet change practice.
The purpose of the present study was to investigate the influence of two exercise intensities (moderate and severe) on heart rate variability (HRV) response in 16 runners 1 hr prior to (-1 hr) and at +1 hr, +24 hr, +48 hr, and +72 hr following each exercise session. Time domain indexes and a high frequency component showed a significant decrease (p < .001) between -1 hr and +1 hr for severe intensity. The low frequency component in normalized units significantly increased (p < .01) for severe intensity at +1 hr. Only severe exercise elicited a change in HRV outcomes postexercise, resulting in a reduction in the parasympathetic influence on the heart at +1 hr; however values returned to baseline levels by +24 hr.
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James et al. (2012) conducted an RCT in Healthy experienced runners (n=16). Severe intensity interval training vs. Moderate intensity interval training was evaluated on Time domain outcomes of heart rate variability at 1 hour post-exercise (p=<0.01). Severe intensity interval training significantly reduced time domain indices of heart rate variability by 11-55% at 1 hour post-exercise compared to moderate intensity training (p<0.01).
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