Key facts
- Usually divided into five zones.
- Lower zones build aerobic base; higher zones push capacity.
- Based on a percentage of max heart rate.
- Help you train at the right intensity for your goal.
Heart rate zones turn 'how hard am I working?' into measurable ranges, typically five, each defined as a percentage of your maximum heart rate. Low zones (1–2) are easy aerobic work that builds endurance and aids recovery; middle zones (3) are moderate; high zones (4–5) are hard efforts that push your VO2 max and anaerobic capacity.
Training by zones helps you spend the right amount of time at each intensity rather than always grinding in the middle. A common approach is doing most cardio easy (Zone 2) to build a base, with a smaller dose of hard, high-zone work to raise your ceiling.
Frequently asked questions
How many heart rate zones are there?
Most systems use five zones, from very easy (Zone 1) to maximal effort (Zone 5), each defined as a percentage range of your maximum heart rate.
Which heart rate zone burns the most fat?
Lower zones burn a higher proportion of fat, but total calories burned matters more for fat loss. For overall fitness, training across zones is most effective.
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