In brief:
- Heart rate zones are divided into 5 levels that show training intensity as a percentage of maximum heart rate.
- Maximum heart rate is roughly calculated with the formula 208 − 0.7 × age (Tanaka et al., 2001).
- The most effective endurance training follows an 80/20 split: 80% of volume at low intensity (zones 1–2) and 20% at high intensity (zones 4–5).
- The Estonian Health Board recommends that adults get at least 150 minutes of moderate-intensity activity per week.
Heart rate zones are the foundation of effective cardio training – they show exactly how hard your heart is working and which energy systems your body is currently using. Choosing the right zone helps you achieve the training effect you want, whether your goal is fat burning, building endurance or developing speed endurance.
What are heart rate zones and how are they calculated?
Heart rate zones are based on maximum heart rate (MHR – maximal heart rate). The most common approximation formula is 220 minus age, but the Tanaka formula is considered more accurate: MHR = 208 − 0.7 × age (Tanaka et al., 2001). For example, the estimated maximum heart rate of a 35-year-old trainee is roughly 184 beats per minute.
The classic 5-zone model (Garber et al., 2011):
| Zone | % MHR | Name | Feel |
|---|---|---|---|
| 1 | 50–60% | Recovery zone | Very easy, you can chat freely |
| 2 | 60–70% | Endurance zone | Easy, aerobic burn |
| 3 | 70–80% | Aerobic zone | Moderate, breathing quickens |
| 4 | 80–90% | Threshold zone | Hard, speaking in full sentences is difficult |
| 5 | 90–100% | Maximum zone | Very hard, bearable for only seconds up to a minute |
Choosing the right time to train also influences which zone makes sense to work in – morning sessions often suit lower-intensity work, while the body is still fully waking up.
How does training in each zone affect the body?
Zones 1 and 2 (50–70% MHR) are optimal for building an aerobic base. In this range the body mainly uses fat as fuel, capillary density in the muscles increases and the heart muscle becomes more efficient (Garber et al., 2011). It is also ideal recovery training after hard sessions.
Zone 3 (70–80% MHR) improves general endurance, but the energy source shifts more toward carbohydrates. This range is sometimes called the “gray zone” – it is neither easy enough for recovery nor hard enough to trigger maximum adaptation.
Zone 4 (80–90% MHR) is the lactate threshold zone. Regular training in this range raises the threshold at which lactic acid builds up, which is one of the most effective ways to improve endurance at race pace (Seiler & Kjerland, 2006).
Zone 5 (90–100% MHR) – interval training here improves VO₂max and anaerobic capacity. Buchheit and Laursen (2013) showed that high-intensity interval training is effective for raising VO₂max, but it requires sufficient recovery time and is not suitable for everyday training.
Why training on a rowing machine is beneficial – a rowing machine is one of the few pieces of training equipment that loads the upper and lower body evenly, and it works well for training in every heart rate zone, including as low-intensity recovery sessions.
How much time should you spend training in different zones?
An analysis of the training of elite endurance athletes showed that about 80% of volume is done at low intensity (zones 1–2) and only about 20% at higher intensity (zones 4–5) – the so-called polarized 80/20 distribution (Seiler & Kjerland, 2006). This approach has proved more effective than spending most of your time in the “middle zone” (zone 3).
The Estonian Health Board recommends that adults get at least 150 minutes of moderate-intensity (zones 2–3) or 75 minutes of high-intensity (zones 4–5) cardio activity per week. Tracking your heart rate zones with a heart rate watch helps you follow these recommendations more precisely and avoid an excessive or insufficient training load.
How do you use heart rate zones in practice?
Step 1 – determine your maximum heart rate. A laboratory VO₂max test gives the most accurate result, but in everyday life a maximal effort test after a thorough warm-up (e.g. a set of uphill sprints) with a heart rate watch is enough.
Step 2 – choose a zone based on your goal. Recovery and fat burning → zones 1–2; general endurance → zone 3; raising the lactate threshold → zone 4 as intervals; speed endurance → zone 5 as short sets.
Step 3 – record your data. A training log in which you note your average heart rate, RPE (rating of perceived exertion, 1–10) and your performance helps you see progress over weeks and months.
Aerobic training in zones 2–3 also supports brain health, among other things. One way to train your brain is precisely moderate cardio activity, which increases BDNF production and supports neuroplasticity. This is especially important for older people – 7 tips for training your brain in older age confirm that regular training in zones 1–2 is a safe and effective way to keep both body and mind in shape.
References
- Tanaka H, Monahan KD, Seals DR. (2001). Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 37(1):153–6. PMID: 11153730
- Garber CE, Blissmer B, Deschenes MR, et al. (2011). Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults. Med Sci Sports Exerc. 43(7):1334–59. PMID: 21694556
- Seiler KS, Kjerland GØ. (2006). Quantifying training intensity distribution in elite endurance athletes: is there evidence for an “optimal” distribution? Scand J Med Sci Sports. 16(1):49–56. PMID: 16430681
- Buchheit M, Laursen PB. (2013). High-intensity interval training, solutions to the programming puzzle: Part I: cardiopulmonary emphasis. Sports Med. 43(5):313–38. PMID: 23539308
Frequently asked questions
How do I calculate my heart rate zones without lab testing?
Use the Tanaka formula: MHR = 208 − 0.7 × age. Then multiply that number by the percentage range of each zone (e.g. zone 2 = MHR × 0.60–0.70). A maximal effort test done with a heart rate monitor will give you a more accurate result.
Is a wrist heart rate sensor accurate enough for tracking heart rate zones?
A wrist sensor is fine for everyday training, but for high-intensity interval training (zones 4–5) a chest strap (e.g. Polar H10) is considerably more accurate, because wrist sensors are slow to respond to rapid changes.
Does fat burning only happen in zone 2?
Fat makes up the largest share of your fuel in zones 1–2, but absolute calorie expenditure rises with intensity. For fat loss, it’s advisable to combine longer low-intensity sessions with regular interval training.
How many times a week should I train in zones 4–5?
The ACSM recommends 1–2 high-intensity sessions a week, with adequate recovery. More frequent high-zone workouts increase the risk of overtraining and injury and bring no extra benefit.
Do heart rate zones change with age?
Yes – maximum heart rate drops by roughly 1 beat per year of age, so your zone calculations need to be updated from time to time. The zones of a 50-year-old athlete are noticeably lower than those of the same athlete at 30.
Come and train! ArtGym
