Instead of a fixed plan that says Tuesday is interval day, let your body vote. A morning heart rate variability (HRV) reading can tell you whether today is a good day to push.
// 01Why it works
- HRV reflects recovery. HRV is the beat-to-beat variation in your heart rate. When you're well recovered, it tends to sit at or above your normal range. Fatigue, poor sleep, illness and alcohol tend to push it down.
- HRV-guided training has been tested. In a Finnish trial, runners who did hard sessions only when their HRV was normal or high improved their performance more than runners on a fixed plan.
- The trend beats the single number. Research on elite athletes shows a single day's value is noisy. A rolling 7-day average is far more meaningful.
How to do it this week
- Measure the same way daily: on waking, before coffee, in the same position. Overnight readings from a watch or ring also work.
- Build a baseline. Collect 1–2 weeks of data before acting on it.
- Use a simple rule: if the 7-day average is in or above your normal range, train hard. If it's clearly below, go easy or rest.
- Cross-check how you feel. Low HRV plus heavy legs means back off. Low HRV alone on a day you feel great can be noise.
Common mistakes: comparing your HRV to other people's (it's very individual), panicking over one low morning, and switching devices mid-trend, since different brands give different numbers.
Sources
- Kiviniemi AM et al. Endurance training guided individually by daily heart rate variability measurements. Eur J Appl Physiol, 2007. PubMed 17849143
- Plews DJ et al. Training adaptation and heart rate variability in elite endurance athletes. Sports Med, 2013. PubMed 23852425