Understanding Heart Rate Training Zones
Training within specific heart rate zones allows you to target different physiological adaptations during exercise. The classic five-zone model divides exercise intensity based on percentage of maximum heart rate (Max HR). Your Max HR is estimated using the widely-used formula: 220 − age. Zone 1 (50–60%) is gentle recovery work. Zone 2 (60–70%) is the fat-burning aerobic base zone. Zone 3 (70–80%) develops cardiovascular fitness. Zone 4 (80–90%) pushes your lactate threshold. Zone 5 (90–100%) is maximum sprint effort. Training across all zones creates a well-rounded fitness programme. The optional Karvonen method refines zones using your resting heart rate for even more personalised targets.
Frequently Asked Questions
How accurate is the 220 − age formula?
The 220 − age formula is a population average with a standard deviation of about ±10–12 bpm. It works well for most people but can overestimate max HR in older adults and underestimate it in very fit individuals. An actual max HR test (supervised exercise test) provides a more accurate measurement.
What is the best zone for fat burning?
Zone 2 (60–70% of max HR) is traditionally called the "fat burning zone" because fat is the primary fuel source at this intensity. However, higher intensity zones burn more total calories per minute, which may be more effective for overall fat loss. Zone 2 training also builds the aerobic base needed for all other training.
What is the Karvonen method?
The Karvonen heart rate reserve (HRR) method uses your resting HR to personalise training zones: Target HR = Resting HR + (HRR × intensity%). Where HRR = Max HR − Resting HR. This produces slightly higher zone targets than the standard % of Max HR method.