Introduction
Training without knowing your heart rate zones is like driving without a speedometer. Heart rate zone training allows you to exercise at precisely the right intensity to achieve your specific goals — whether that’s burning fat, building aerobic capacity, or peaking for performance.
What Are Heart Rate Zones?
Heart rate zones are ranges expressed as percentages of your maximum heart rate (MHR). The most widely used system divides exercise intensity into five zones based on the formula: MHR = 220 − Age.
The Five Zones Explained
Zone 1 (50–60% MHR) — Warm-up: Very light intensity. Ideal for warm-ups, cool-downs, and active recovery on rest days. Feels like a gentle stroll.
Zone 2 (60–70% MHR) — Fat Burn: Moderate intensity. Your body primarily burns fat as fuel. Perfect for long, easy runs, cycling, or any sustained aerobic activity. Most of your training should be here.
Zone 3 (70–80% MHR) — Aerobic: Comfortable but challenging. Improves cardiovascular efficiency. You can speak in sentences but not hold a full conversation.
Zone 4 (80–90% MHR) — Anaerobic: Hard effort. Lactate builds faster than it can be cleared. Builds speed and performance. Sustainable only for shorter intervals.
Zone 5 (90–100% MHR) — Maximum: All-out sprint. Only sustainable for seconds to minutes. Builds peak power and speed.
How to Structure Your Training
Elite endurance athletes follow the 80/20 rule: 80% of training time in Zones 1–2, 20% in Zones 3–5. This polarised approach builds an aerobic base while including enough high-intensity work for performance adaptation.
Measuring Your Heart Rate
A chest strap monitor is the most accurate. Optical wrist-based monitors (smartwatches) are convenient but can be less accurate during high-intensity work. Manual pulse checks are reliable for steady-state exercise.