Heart rate zone training has gained popularity with the rise of wearable fitness technology, which enables users to track heart rate and optimize workouts. Heart rate zones represent different levels of intensity during aerobic exercise, typically measured as a percentage of maximum heart rate, the highest number of beats per minute your heart can achieve (MHR). MHR can be estimated using the formula: 208 – (0.7 × age in years).
The Three-Zone Model
Athletic training is most commonly classified into the three-zone model, which is as follows:
Zone 1: 55%–82% of MHR
Zone 2: 82%–87% of MHR
Zone 3: 87%–97% of MHR
These zones are structured around an individual's lactate threshold—the point where the body shifts from aerobic to anaerobic exercise. Aerobic exercise uses oxygen for sustained activity, while anaerobic exercise relies on stored energy and produces metabolic byproducts like lactate, leading to fatigue. We can only produce energy anaerobically for short periods, whereas aerobic activity is built on endurance. The average lactate threshold is around 85% of MHR, though it varies by individuals and is usually higher in athletes.
Training Methods by Zone
Each zone aligns with a specific type of training:
Zone 1: Low-intensity, high volume exercise below the lactate threshold where you can carry a conversation - think walking on the treadmill and chatting with your friend.
Zone 2: Moderate-intensity threshold training, also known as tempo training, where speaking in full sentences is difficult (e.g., running, rowing, or cycling at a steady, challenging pace).
Zone 3: High-intensity interval training (HIIT), performed in short bursts above the lactate threshold (e.g., circuit workouts with alternating 30-second exercise and rest intervals). You’re not discussing the state of the world prolifically during this type of activity.
Optimizing Training for Performance and Health
To improve endurance, individuals must balance training intensity to avoid overtraining, injury, and burnout. Zone 3 provides the greatest improvement in maximal oxygen uptake (VO₂ max), a key predictor of endurance and overall health, but your body tires from this training zone the quickest.
Elite endurance athletes (runners, rowers, and cross-country skiers) typically spend about 80% of their training in Zone 1, with the remaining 20% split between Zones 2 and 3 to prevent excessive fatigue. Non-professional athletes can apply this principle while meeting World Health Organization (WHO) exercise guidelines:
150–300 minutes of moderate-intensity exercise (Zone 1) per week
OR
75–150 minutes of vigorous-intensity exercise (Zones 2 & 3) per week
Training Without a Heart Rate Monitor
Heart rate zones can also be estimated using a 10-point effort scale, where:
Zone 1 feels like 4 or less out of 10
Zone 2 is 4.5–6.5 out of 10
Zone 3 is 7 or higher out of 10
While heart rate zones provide valuable guidance, keeping it simple is key: are you sweating from moving your body? If yes, keep up the good work.