Summary
Ultra-endurance events (64km+) significantly suppress HRV for 1-2 days post-race, with 100-mile events requiring up to a week for full HRV recovery. Faster finishers often show greater autonomic disturbance.
Methods
Multiple studies on 64km to 100-mile ultra-marathons
Key Findings
- HRV suppressed 1 day post-race for 64km events
- HRV returned to baseline by day 2 for shorter ultras
- 100-mile races: HRV may not recover within one week
- Faster runners showed greater HRV disruption
- Perceptual fatigue took 5 days to resolve
Limitations
Individual variation significant, training status matters
What This Means for You
After ultra-endurance events, expect 2-7+ days for HRV to normalize depending on race distance. Don't resume hard training until HRV returns to your baseline—perceptual recovery often lags.
Source
Read the original paper in European Journal of Applied Physiology ↗
Added to HRV Zone: 2025-01-10