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Heart-Rate Training Zones

Five-zone and Karvonen methods compared. Pick one or both. No more guessing what your watch means by “Zone 3”.

5-zone (% of max HR)

Karvonen (HRR — heart-rate reserve)

Karvonen uses a fraction of (max − resting). It shifts zones up for athletes with low resting HR.

Why your watch’s “Zone 3” and a lab’s “Zone 3” are not the same

Consumer watches default to 220 − age for max HR. That formula has a standard error of about ± 10 bpm — meaning your “max” might be 195 or 175 and the formula can’t tell you which. Worse, an 18-year-old at 75% of max is genuinely working harder than a 50-year-old at the same %.

Which method should I use?

  • % of max (5-zone) — quick, requires no test. Good for beginners and most team settings.
  • Karvonen (HRR) — better for trained athletes whose resting HR is far below average (e.g. 45 bpm). Costs you a 60 s measurement of resting HR.
  • Best of both — if your watch lets you set zones manually, average the two results. Or pick the higher (Karvonen) for trained athletes.

How to read the zones

  1. Z1 — recovery, warm-up, cool-down. You can hold a conversation.
  2. Z2 — aerobic base. Long, slow, conversational. Build most of your volume here.
  3. Z3 — tempo. Talking in short sentences only.
  4. Z4 — threshold. Can’t speak comfortably. Lactate starts accumulating.
  5. Z5 — VO2max. All-out intervals. 1–5 min efforts with full recovery.

Limitations

  • Max HR doesn’t change much with fitness — but it does drift down with age.
  • HR is delayed by ~30 s relative to actual effort (cardiac drift). Don’t chase a number; use it as a check, not a target.
  • Caffeine, sleep, illness, heat all shift HR by ± 5–15 bpm. Use HR as a sanity check, not a primary measure of intensity.

FAQ

Where do I measure resting HR?

First thing in the morning, lying down, before you get up. Average three consecutive mornings. Anything below 60 is athlete-grade; below 50 is elite-endurance territory.

My watch sets max HR from 220 − age. Should I trust it?

It’s a starting point. If you’ve ever done an all-out 3×3 min test and seen your peak HR, use that. If not, the Tanaka formula here is slightly less biased for older athletes than 220−age.

What about a player on beta-blockers?

Beta-blockers suppress max HR. Use a Rating of Perceived Exertion (RPE) scale instead. This tool will still give numbers, but they will not reflect true effort.