foundations

HRV vs VO2 Max vs ECG: Which Smartwatch Metric Matters?

Decode popular health metrics and learn which ones to track for healthspan (and how to use them).

Published July 2026

Key Takeaways

Track trends rather than single-day values
VO2 Max improves with consistent aerobic work
ECG features are for specific use-cases with medical input

What to track and why

HRV: a proxy for recovery readiness; track trends, not single days
VO2 Max: cardiorespiratory fitness; improves with intervals + zone 2
ECG spot checks: for those with clinician guidance or symptoms

Practical use

Use metrics to shape habits (sleep, training load), not to obsess daily

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