Find your 5 training zones by age and resting heart rate.
The Karvonen method calculates training zones using Heart Rate Reserve (HRR = Max HR − Resting HR), which is more accurate than using max HR alone because it accounts for your fitness level. The formula: Target HR = (HRR × intensity%) + Resting HR.
Zone 2 (aerobic base) is the most important zone for building endurance and fat-burning capacity. Elite endurance athletes spend 80% of their training time in Zone 2.