HRV Expert

Your heart is not a metronome.

The small changes in time between your heartbeats are called heart rate variability, or HRV. They change with sleep, stress, training and illness. Learn to read them here, free and without an account.

Start learning Check your HRV

A metronome every gap 1.000 s

A resting heart gaps 0.950–1.052 s

Ticks mark heartbeats; the line below plots the gap before each beat. Both average 60 beats per minute, but the heart's gaps lengthen and shorten with each breath. That variation is HRV. Illustrative recording, RMSSD 43 ms.

A free course in short lessons

Each lesson takes five to eight minutes and ends with a short quiz. Your progress stays on this device.

  1. Level 1 Foundations

    1. What your heartbeat is really doing
    2. What HRV is, in one picture
    3. The nervous system behind HRV
    4. Why higher is not always better
    5. How HRV is measured

  2. Level 2 Reading your numbers

    1. RMSSD, SDNN and lnRMSSD
    2. What's normal, by age, sex and fitness
    3. Why your devices disagree
    4. How to take a good reading
    5. Building your baseline and reading trends

  3. Level 3 Using HRV well

    1. What moves HRV
    2. HRV for training and recovery
    3. HRV, stress and breathing
    4. Limits, myths and red flags
    5. Final quiz

See the course

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