Heart Rate Variability (HRV)
Heart rate variability (HRV) is the small, natural variation in the time between consecutive heartbeats. Even when your heart rate feels steady, the exact gap between one beat and the next is constantly shifting by a few milliseconds. Those fluctuations reflect how your autonomic nervous system — the system that regulates things like heart rate, breathing, and digestion — is balancing its “stress” (sympathetic) and “recovery” (parasympathetic) branches. That makes HRV a useful window into recovery, stress load, and overall physiological state.
How Reckon measures it
Reckon measures the time between each heartbeat — the peak-to-peak interval — in milliseconds, and tracks how much that interval changes from beat to beat. Greater beat-to-beat variation generally points toward a more recovered, parasympathetic-dominant state; less variation tends to reflect higher stress or fatigue.
Rather than judging any single reading, Reckon builds a rolling 7-day average to establish your personal baseline. Each new measurement is then compared against that baseline, and the deviation — how far above or below your norm you are — is what we treat as the meaningful signal. That deviation acts as a proxy for your current autonomic balance and feeds directly into your Training Readiness score.
Why your numbers are personal
There is no universal “good” HRV. A healthy value depends on factors like age, fitness, genetics, and overall health, and it’s completely normal for two people to have very different absolute numbers while both being well-recovered. For that reason, your absolute HRV matters far less than your trend. A reading that sits well below your own baseline tells you more than how your number compares to anyone else’s.
Supporting a healthy HRV
HRV responds to the same things that support recovery in general: consistent, well-managed training, quality sleep, good hydration and nutrition, and managing day-to-day stress. Watching your deviation over time — rather than chasing a single number — is the most reliable way to understand how your body is adapting.