Training Zone Guide
| Zone | Feel | Primary Benefit | Typical Session |
|---|---|---|---|
| Zone 1 - 50-60% | Very easy | Recovery, warm-up | Any duration |
| Zone 2 - 60-70% | Comfortable, can talk in sentences | Aerobic base, a high share of energy from fat | 30-180 min |
| Zone 3 - 70-80% | Moderate effort, short sentences | Cardiovascular fitness | 20-60 min |
| Zone 4 - 80-90% | Hard | Lactate threshold, speed | Intervals, 10-30 min in total |
| Zone 5 - 90-100% | Maximum | Peak power, VO2 max | Short intervals, 1-5 min each |
Five-zone systems are a coaching convention, and different coaches draw the lines in slightly different places. The American Heart Association uses two broader bands: about 50 to 70% of maximum for moderate exercise and 70 to 85% for vigorous exercise. If you are new to exercise, it suggests starting at the low end.
On "fat burning": at easy intensity a larger share of the energy you burn comes from fat, but you burn fewer calories per minute. For weight loss, total calories burned over the week and your diet matter more than staying in one zone.
Formula Comparison by Sex and Age
Fox (220 − age): Classic formula, widely used. It was never derived from a proper study and tends to underestimate maximum heart rate for older adults and overestimate it for young adults.
Tanaka (208 − 0.7 × age): From a 2001 meta-analysis of 351 studies with about 18,700 people, confirmed in a lab study. It works for men and women in healthy adults.
Gulati (206 − 0.88 × age): Derived from exercise tests in more than 5,000 women aged 35 and over in the St. James Women Take Heart Project (2010). The calculator's Auto setting uses it for women and Tanaka for men.
Gellish (206.9 − 0.67 × age): From a 2007 study that followed the same adults with repeated treadmill tests over years. Its results sit close to Tanaka's.
Note: an individual's real maximum can differ from any of these by 10 beats a minute or more. For precision, a supervised maximal exercise test is the only real measurement.
The Karvonen method, with a worked example
Karvonen uses your heart rate reserve, the gap between maximum and resting heart rate, so fitter people with a low resting rate get zones that fit them better.
Target = resting HR + intensity × (max HR − resting HR)
Worked example. A 40-year-old man with a resting heart rate of 60. Tanaka max: 208 − 0.7 × 40 = 208 − 28 = 180 BPM. Reserve: 180 − 60 = 120. At 70% intensity: 60 + 0.7 × 120 = 60 + 84 = 144 BPM. The plain percentage method gives 0.7 × 180 = 126 BPM for the same zone, 18 beats lower.
When heart rate targets do not apply
Beta-blockers and some other heart and blood pressure medicines lower your heart rate, so formula zones will be too high. People with heart disease, or who are pregnant, should get targets from their doctor. Stop and get medical help if you have chest pain, faintness or unusual shortness of breath during exercise. A resting heart rate for adults is usually 60 to 100 beats a minute according to the American Heart Association; well-trained people can be lower.