FAQ: Heart Rate Zones

How do I determine my resting heart rate?

The best way to measure your resting heart rate is to use a watch or a heart rate monitor before you get out of bed in the morning (and before your first cup of coffee, since caffeine stimulates the heart rate). Some athletes even sleep with their heart rate monitor strap on!

As you get fitter, your resting heart rate should gradually reduce (unlike your maximum heart rate, which falls slowly with age but is not much affected by fitness).

If you notice a blip up in your resting heart rate one morning, this is a sign of overtraining or impending illness.

What is my heart rate reserve or working heart rate? What is the Karvonen formula?

Your heart rate reserve is the gap between your resting heart rate and your maximum heart rate. For example, my maximum heart rate is 190bpm (four beats a minute higher than the rule of thumb based on my age predicts); and my
resting heart rate is 48bpm. This means my heart rate reserve is:
HRR = 190 – 48 = 142 bpm.

To get the heart rate corresponding to the aerobic threshold, which is at 85% of my heart rate reserve, I have to add 85% of my heart rate reserve rate to my resting heart rate. So the heart rate corresponding to my
aerobic threshold is estimated to be: AT = 48 + (0.85 x 142) = 169.

This way of calculating a heart rate zone is known as the Karvonen formula.

What are the heart rate zones?

Click here for a tool to estimate your own heart rate zones.

Zone What it does % of Heart Rate
Reserve (Karvonen)
Long, slow runs, easy or recovery runs

Training in this zone improves the ability of your heart to pump blood and improve the muscles' ability to utilize oxygen.  The body becomes more efficient at feeding the working muscles, and learns to metabolise fat as a source of fuel.

Aerobic zone or "target heart rate zone"

Most effective for overall cardiovascular fitness. Increases your cardio-respitory capacity: that is, the your ability to transport oxygenated blood to the muscle cells and carbon dioxide away from the cells.  Also effective for increasing overall muscle strength.

Anaerobic zone The point at which the body cannot remove lactic acid as quickly as it is produced is called the lactate threshold or anaerobic threshold. It generally occurs at about 80-88% of the Heart Rate Reserve. Training in this zone helps to increase the lactate threshold, which improves performance. Training in this zone is hard: your muscles are tired, your breathing is heavy. 80-90%
VO2 max
"Red line zone"
You should only train in this zone if you re very fit, and only for very short periods of time. Lactic acid develops quickly as you are operating in oxygen debt to the muscles   The value of training in this zone is you can increase your fast twitch muscle fibers which increase speed. 90-100%

Does it matter where in the heart rate zone I train?

Yes. Training at particular heart rates in the zone will be more beneficial for you in terms of the impact on your body. Have a look at the heart rate training paces.

See also