Maximum heart rate and training zones: a practical guide

The heart is the engine of physical exercise. The more beats per minute, the more oxygen reaches the muscles and the more energy can be produced. Maximum heart rate (MHR) is the upper limit of that engine: the number of beats it can reach at maximum exertion. Knowing it is the first step to training intelligently and efficiently.

Why is it important to know your MHR?

Training without a heart rate reference is like driving without a speedometer: you might be going too fast without knowing it (overtraining) or too slowly to see results (understimulation). With MHR as a reference, you can calculate your training zones and ensure that each session meets its physiological objective.

The Tanaka formula: more accurate than 220 − age

The classic '220 − age' formula is a simplification that can under- or overestimate MHR by ±12 bpm. The Tanaka formula (2001), validated in a meta-analysis of more than 18,000 people, is more accurate: MHR = 208 − (0.7 × age). For a 40-year-old, both formulas give 180 bpm, but at extreme ages the difference can be 10–15 bpm.

The 5 training zones

• •Zone 1 (50-60% MHR) — Active recovery: warm-up, cool-down and recovery days. Very low intensity.
• •Zone 2 (60-70% MHR) — Base aerobic: fat burning as primary fuel, improved aerobic endurance. The most important zone for endurance runners.
• •Zone 3 (70-80% MHR) — Upper aerobic: cardiovascular improvement, VO₂max increase. Conversation possible but with effort.
• •Zone 4 (80-90% MHR) — Anaerobic threshold: improves power and performance in 20–60 minute efforts. Difficult to hold a conversation.
• •Zone 5 (90-100% MHR) — Maximum effort: develops peak power and VO₂max. Short sprints only. Not sustainable for more than 1–3 minutes.

How to distribute training across zones?

Sports science researchers recommend the polarised model: 80% of volume in Zones 1–2 (low intensity) and 20% in Zones 4–5 (high intensity), avoiding Zone 3 which generates fatigue without the benefits of either extreme. This model is used by most elite endurance athletes.

Is it safe to train near MHR?

For healthy people with no cardiovascular risk factors, Zone 4–5 training is safe once a solid aerobic base (Zones 1–3) has been built over at least 8–12 weeks. If you are over 40, have been sedentary for a long time, or have a history of heart disease, consult your doctor before undertaking high-intensity exercise.