Heart Rate Training Zones

Heart rate training zones: rule and example

The usual estimate for maximum heart rate is FCmax = 220 - age, though the Tanaka version (208 - 0.7 × age) tends to hold up better. Five zones cover the range: Z1 50-60% (recovery), Z2 60-70% (aerobic base), Z3 70-80% (tempo), Z4 80-90% (lactate threshold), and Z5 90-100% (VO2 max). Take a 30-year-old with an FCmax of 190: their Z2 works out to 114-133 bpm. If you know your resting heart rate, Karvonen's formula gets you closer to the truth by working off the heart rate reserve (HRR = FCmax - resting HR).

Applications and methodology

Stephen Seiler's polarized 80/20 model puts 80% of training volume in Z1-Z2 and 20% in Z4-Z5, deliberately skipping most of Z3. It's how a lot of elite runners, cyclists and triathletes structure their weeks. Garmin Connect, Strava, Polar Flow and Whoop will work the zones out for you from FCmax or lactate threshold. Each sport leans on a different one: Z2 builds the aerobic base in running, Z4 develops FTP on the bike, and short Z5 sets sharpen speed in the pool. One practical note for intervals — a chest strap reads more accurately than a wrist-only optical sensor.

FAQ

Which formula is most accurate? Karvonen paired with an FCmax you've actually measured in a field test. The 220 - age shortcut can be off by ±10-12 bpm.

How much time in each zone? If you're starting out, aim for roughly 80% Z2 and 20% Z3-Z4. More advanced athletes tend to run the 80/20 polarized split (Z2 plus Z4/Z5).

Can I train every day in Z4-Z5? Don't. You'll dig yourself into overtraining. High-intensity sessions want 48-72 hours of recovery between them.

Does the same zone fit running and cycling? Not really. FCmax usually comes in 5-10 bpm lower on the bike, since cycling recruits less muscle mass.