Target heart rate zones

Heart rate zones help you monitor the intensity of endurance training. Our bodies produce energy in different ways during different intensity exercises, and the physiological effects of exercises on the body are different.

To calculate your target heart rates, you need your maximum heart rate and your resting heart rate. You can calculate your maximum heart rate with a maximum heart rate calculator. You can calculate your resting heart rate, for example, by counting the number of heartbeats while resting for 15 seconds by pressing on your carotid artery. Multiply the number of beats by four to get your heart rate per minute, i.e. your current heart rate. Most people's resting heart rate falls between 60 and 100 beats.

Target heart rates are calculated using the Karvonen formula

Target heart rates can also be calculated directly from maximum heart rate, but adding the resting heart rate allows for the use of the Karvonen formula, which better takes into account personal condition.

Karvonen formula:

target heart rate = (maximum heart rate - resting heart rate)

\times exercise level (%) + resting heart rate

Target heart rate zone descriptions

Zone 1: 50-60%
Very light exercise

energy production mainly from fat
training in the heart rate zone can be continued for a long time
exercising basic endurance
develops endurance fitness and the body's oxygen utilization capacity
exercising mainly with slow muscle cells
easy to talk
example: warm-up

Zone 2: 60-70%
Light exercise

energy production mainly from fat
training in the heart rate zone can be continued for a long time
exercising basic endurance
develop endurance fitness and the body's oxygen utilization capacity
exercising mainly with slow muscle cells
reasonably easy to talk
example: long-duration run

Zone 3: 70-80%
Moderately strenuous exercise

energy production from fats and carbohydrates
aerobic threshold is usually in this range
exercising endurance
lactate formation increases
develops oxygen uptake and aerobic capacity as well as the body's ability to remove lactate
exercising mainly with slow muscle cells, but the involvement of fast muscle cells also increases
speaking becomes more difficult
example: brisk run

Zone 4: 80-90%
Heavy exercise

energy production mainly from carbohydrates
exercising endurance
lactate formation increases
develops oxygen uptake and aerobic capacity capacity and the body's ability to remove lactate
training takes place with slow and fast muscle cells
talking is difficult
example: fast-paced running or interval training

Zone 5: 90-100%
Really hard exercise

energy production from carbohydrates
develops maximum endurance and anaerobic energy production
the anaerobic threshold is exceeded and lactate formation is faster than the body's ability to remove lactate
training takes place with slow and fast muscle cells
talking is really difficult
example: near-maximal interval training

Aerobic threshold: (75%)

Aerobic threshold refers to the maximum exercise intensity at which the blood lactate level does not rise above the resting level. Once the aerobic threshold is exceeded, the blood lactate level begins to rise. However, in aerobic exercise, the removal of lactate from the body is more efficient than the production of lactate. Endurance properties are also better in the aerobic range (the range between the aerobic and anaerobic threshold) than in the anaerobic range. Personal aerobic threshold can vary greatly between individuals, and is usually calculated at an intensity of 70–75 percent (75% in the calculator).

Anaerobic threshold: (90%)

Anaerobic threshold refers to the maximum exercise intensity at which the production of lactate and the removal of lactate are in balance. When the anaerobic threshold is exceeded, more lactate is produced than the body can remove it. This leads to rapid exhaustion and the intensity level can often only be maintained for a few minutes. The anaerobic threshold can also vary between individuals, but in calculations it is usually set at 85–90% (90% in the calculator).

Training raises both aerobic and anaerobic thresholds.

Author

Lassi Honkanen
physiotherapist

Sources:

Cleveland Clinic. 2023. Heart Rate Zones Explained. https://health.clevelandclinic.org/exercise-heart-rate-zones-explained

Nummela, A. Hynynen, E. Mikkola, J. Vesterinen, V. 2022. Kestävyysharjoittelu - tutkitulla tiedolla tuloksiin. Lahti: VK-Kustannus Oy.

TriathlonSuomi. Sykerajojen määrittäminen ja harjoittelu. https://triathlonsuomi.com/harjoittelu/harjoitusten-tehosta-maarasta-ja-palautumisesta/sykerajojen-maarittaminen-ja-harjoittelu/