Heart-rate training zones, explained
What Z1–Z5 actually mean, how to find your max heart rate, and how to train each zone.
The Tanaka formula — 208 minus 0.7 times your age — predicts maximum heart rate more accurately across ages than the older 220-minus-age rule. Your five zones are then percentages of that maximum.
Finding your max heart rate
The Tanaka formula — 208 minus 0.7 times your age — predicts maximum heart rate more accurately across ages than the older 220-minus-age rule. Your five zones are then percentages of that maximum.
What each zone trains
Z1–Z2 build aerobic base and recovery, Z3 is tempo, Z4 sits at lactate threshold, and Z5 develops VO₂ max. Most endurance gains come from spending the majority of training time in Z2.
Mifflin MD, St Jeor ST, et al. Am J Clin Nutr. 1990 · Tanaka H, et al. J Am Coll Cardiol. 2001 · Morton RW, et al. Br J Sports Med. 2018 · Reviewed by Dr. Lena Okafor, MD (Endocrinology), Feb 2026.