HRV and Exercise

Measuring HRV During Exercise is Complicated

Firstly, tracking your heart rate variability (HRV) is very different than tracking your heart rate (HR).

Tracking your HRV during exercise sessions is of limited value for two reasons:

1. as your heart rate increases to supply your muscles more oxygen, the variability between heartbeats (HRV) is suppressed
2. you also have a much higher chance of introducing movement artifacts, even with a well-fitting chest strap (and wrist worn devices will be much worse). This does not matter as much for HR training, but does for tracking HRV, which is far more sensitive.

If your trainer or coach wishes you to track your HRV during exercise, be sure you're using a good chest strap (list of Compatible Devices (link)) and follow their guidance on what to look for.

Our Recommendations for Using HRV With Exercise

The best value you'll get from HRV for exercise is to

1. track your HRV routinely (multiple times per week)
2. along with workout intensity and duration,
3. as well as with sleep, and any other big lifestyle factors and stressors (mental, emotional, nutritional, fasting, etc.).

This process can help you find out how your training program is affecting your HRV and to know when to intensify your training OR prioritize recovery.

For example, when your training starts to affect day-to-day HRV less, it could be time to intensify your training either by adding distance, speed, reps, sets, or sessions.

Some notes to consider:

• Exercise and training are a stimulus/stress on the body (targeted stress) which we hope will trigger a positive adaptation over time.
• However, it is also a general stress - if you have stress from a lot of sources, exercise is just another stress and the trick is to track all of these factors.
• When it comes to training and exercise, recovery is where the progress is made. Ex: if you lift a 10lb weight, it doesn't magically make you 10lbs stronger instantaneously. But as recovery kicks in, and tissues repair and rebuild, the muscle gets stronger and gets ready for the next time it encounters that type of stress.
• If you impair your recovery, (inflammatory food, poor sleep, mental stress) you hamper your body's ability to use its available resources for positive adaptation.
• When you're new to the exercise or training program, it'll have a stronger overall impact on your body. You'll need more recovery time between sessions to get full adaptation and recovery.
• As you progress and gain more experience, each rep, set, and session will require more work to challenge your body. Also, recovery speed will improve. This is indicated by your HRV reverting to normal more quickly on a day-to-day basis. You may also feel this faster recovery in less soreness and better energy levels.
• As you adapt to training, you want to see daily HRV fluctuations decrease slightly. Your daily HRV trend may look a little less up and down than before, and your coefficient of variation should go down.
• Each morning when you take your HRV reading, you can expect to see the change either the next day or 2-3 days following a good exercise session. If you don't see this, then you can potentially up the intensity or volume of the next session. Look for adaptation by week 1-2 of a new exercise regimen.
• Sustainable results depend on your recovery! Even professional athletes spend 10 times more hours recovering than training!