Heart rate calculator
The 220-minus-age rule has no research origin — it was an informal approximation that got into print in the 1970s and stuck. Tanaka and colleagues fitted 208 − 0.7 × age to a large meta-analysis in 2001 and it predicts measured maximum considerably better, especially past forty, where 220-minus-age underestimates by several beats. Both are still population estimates with a standard deviation around ten beats, so a measured maximum beats either.
Predicted maximum heart rate varies by about ten beats either side even for people of the same age. Anyone with a heart condition, or starting hard exercise after a long break, should speak to a doctor first.
The Tanaka formula puts maximum heart rate at 208 − 0.7 × age, so a 35-year-old is about 183 bpm. With a resting rate, the Karvonen method sets zones as a percentage of heart rate reserve — maximum minus resting — which is more accurate than percentages of maximum alone.
How to find your training zones
The single most useful zone is Zone 2, the conversational aerobic range, because it builds the aerobic base most training programmes are short of. Most recreational athletes spend far too much time in Zone 3 — hard enough to be tiring, not hard enough to drive adaptation, and too tiring to allow enough volume. The polarised model that most endurance coaching now follows puts roughly eighty per cent of training in Zone 2 and the rest genuinely hard, with very little in between.
Questions
About 208 − 0.7 × your age. For a 40-year-old that is 180 bpm, against 180 from the older 220 − age rule.