Why train by heart rate zones
Heart rate shows how hard the body is really working. At the same pace, one client may be on an easy jog while another is close to their max. Heart rate zones help you set the intensity for each individual – so an easy workout is actually easy and a hard one is actually hard.
Heart rate zone calculator
Age and resting heart rate are all you need. If your client knows their max heart rate, enter that too.
Guideline values for healthy adults. If a client takes medication that affects heart rate or has a health condition, follow their doctor's advice.
Max heart rate: Tanaka formula (2001). Zones 50–100 % follow the common 5-zone model (e.g. Garmin). Karvonen uses percentages of heart rate reserve (max − resting). VO2max: Uth et al. formula (2004).
What each zone means
- Zone 1 – recovery, warm-up and cool-down. You can talk comfortably.
- Zone 2 – base endurance. A comfortable pace where you can still talk. Most endurance training should happen here.
- Zone 3 – moderate intensity. You can only talk in short sentences.
- Zone 4 – pace around the anaerobic threshold, intervals. Talking is hard.
- Zone 5 – short all-out efforts, sprints. Sustainable for only tens of seconds to a few minutes.
Heart rate and VO2max
VO2max is the maximum amount of oxygen the body can take in and use per minute (ml/kg/min). It’s the best measure of endurance fitness – and it’s closely linked to heart rate: oxygen uptake depends on heart rate, on how much blood the heart pumps with each beat, and on how much oxygen the muscles extract from the blood.
Max heart rate barely changes with training, but VO2max does – the heart gets stronger and pumps more blood per beat. That’s why a fit client has a lower resting heart rate and a lower heart rate at the same pace. The calculator above uses this to estimate VO2max with the Uth formula: 15.3 × max heart rate ÷ resting heart rate. It’s only a rough number – most useful for comparing the same client over a few months.
Why VO2max matters
- A strong health marker. In a study of more than 120,000 patients, people with the lowest fitness had roughly 5× higher risk of death than those with the highest (Mandsager et al., JAMA Network Open, 2018).
- Every step counts. An improvement of 1 MET (3.5 ml/kg/min) is linked to about 13% lower risk of death (Kodama et al., JAMA, 2009).
How to improve VO2max
- Mostly easy training. Endurance athletes spend about 80% of their time at low intensity (zones 1–2) and only the rest hard (Seiler, 2010).
- 4 × 4-minute intervals. 4 minutes at 90–95% of max heart rate (zone 5), 3 minutes active recovery, 3× a week. After 8 weeks VO2max improved by about 7% (Helgerud et al., 2007).
- Everyone responds differently. On the same program some people improve a lot, others very little (HERITAGE study, Bouchard et al., 1999). Those who don’t improve often just need more training (Montero & Lundby, 2017).
- It drops fast without training. After 2–3 weeks off, VO2max falls by about 7% (Coyle et al., 1984). On holiday, 1–2 short hard sessions a week are enough.
FAQ
How do you measure max heart rate?
Most accurately with a stress test at a doctor's office or in a lab. A healthy, well-trained client can also estimate it from a watch after a few very hard intervals. For beginners and people with health conditions, the age-based estimate is enough.
What if a client takes blood pressure or heart medication?
Some medications (such as beta blockers) lower heart rate, so the chart doesn't apply. In that case, guide intensity by perceived exertion and the doctor's recommendations.
How often should you update the zones?
When fitness improves and resting heart rate drops, recalculate the zones – usually every 2 to 3 months.
