What heart rate zone should you be training in?

What is the Karvonen formula and why use resting heart rate?

The Karvonen formula calculates a heart rate reserve (max heart rate minus resting heart rate) and applies intensity percentages to that reserve, then adds resting heart rate back: target = resting + intensity% × (max − resting). Because it factors in your resting rate, it accounts for individual fitness differences better than applying a percentage to max heart rate alone — two people with the same max heart rate but very different resting rates will get meaningfully different target zones.

What heart rate zone should I train in?

It depends on your goal — lighter zones (50-70%) suit recovery, warm-ups, and base aerobic building, while higher zones (70-90%) build cardiovascular capacity, speed, and race-pace fitness. Most structured training plans mix zones across a week rather than staying in one permanently. This isn't personalized medical or coaching guidance, so factor in how you actually feel during a session too, not just the number on a monitor.

How do I find my resting heart rate?

Measure your pulse first thing in the morning, before getting out of bed and before caffeine, for the most accurate reading — count beats for a full 60 seconds, or 30 seconds and double it, ideally averaged over a few mornings. Many fitness trackers and smartwatches also estimate this automatically overnight from continuous heart rate monitoring.

Is 220 minus age accurate for everyone?

It's a population average with a meaningful margin of error for any given individual — plus or minus 10-15 beats per minute isn't unusual, meaning some people's true max heart rate is noticeably higher or lower than the formula predicts. It remains a useful starting estimate for most people without access to lab testing, but a supervised maximal exercise test is more accurate if precision genuinely matters for your training.

Worked example: a 35-year-old with a resting heart rate of 70 bpm: max heart rate = 220 − 35 = 185 bpm; heart rate reserve = 185 − 70 = 115 bpm. Fat Burn zone (60-70%) = 70 + 0.60×115 to 70 + 0.70×115 = 139 to 150.5, or roughly 139-151 bpm. Peak zone (80-90%) = 70 + 0.80×115 to 70 + 0.90×115 = 162 to 173.5, or roughly 162-174 bpm.