:INFO Your heart is the most accurate training tool you own Most runners train by feel and end up spending too much time in the grey middle zone: too hard to recover properly, too easy to build real speed. Heart rate zones fix that by anchoring every session to a specific physiological target. This page puts every number you need in one place: zone boundaries, what each one feels like, what it trains, and which workout belongs there. It also gives you two formulas to find your personal max heart rate so the percentages actually apply to you. :IMAGE :INFO Find your max heart rate first Every zone percentage is calculated from your maximum heart rate (MHR). The classic formula is 220 minus your age, which is a population average with a standard deviation of plus or minus 10 to 12 beats per minute. The Tanaka formula (208 minus 0.7 times your age) is more accurate for adults over 40 and is the formula used in sports science research. For the most accurate number of all, run a field test: warm up for 15 minutes, then run hard uphill for 3 minutes, rest 2 minutes, and repeat twice. Your highest reading in the final minute is your practical MHR. Heart rate monitors undercount during the first 20 seconds of a sprint, so give the monitor a moment to catch up before reading the peak. :TABLE [title:Max HR by age: 220-age vs Tanaka formula] Age | 220-age MHR | Tanaka MHR | Difference 20 | 200 bpm | 194 bpm | 6 bpm 30 | 190 bpm | 187 bpm | 3 bpm 40 | 180 bpm | 180 bpm | 0 bpm 50 | 170 bpm | 173 bpm | -3 bpm 60 | 160 bpm | 166 bpm | -6 bpm :INFO The 5-zone model: all parameters in one table The table below uses the 5-zone model adopted by Polar, the British Athletics coaching framework, and most GPS watch manufacturers. Zone boundaries are expressed as a percentage of MHR. RPE is the Borg CR10 scale (0 to 10). Talk test describes whether you can hold a conversation. Workout type gives the most common session that belongs in each zone. :TABLE [title:Five heart rate training zones: complete reference] Zone | Name | % MHR | RPE (0-10) | Talk test | Purpose | Typical workout 1 | Recovery | 50-60% | 1-2 | Full sentences, easy | Active recovery, blood flow | Recovery jog, cool-down walk 2 | Aerobic base | 60-70% | 3-4 | Comfortable, can sing | Fat oxidation, aerobic base | Easy long run, base mileage 3 | Aerobic tempo | 70-80% | 5-6 | Short sentences only | Aerobic capacity, efficiency | Steady-state run, marathon pace 4 | Lactate threshold | 80-90% | 7-8 | A few words at a time | Lactate threshold, speed endurance | Tempo run, threshold intervals 5 | VO2max | 90-100% | 9-10 | Cannot speak | VO2max, top-end speed | VO2max repeats, 400m/800m intervals :NOTE Zone 3 is the grey zone. It is hard enough to accumulate fatigue but not hard enough to drive the adaptations Zone 4 gives you. Most recreational runners spend 60 to 70 percent of their training there by default. Polarised training (80 percent Zone 1-2, 20 percent Zone 4-5, almost no Zone 3) is backed by most current sports science and is the approach used by elite distance coaches. :INFO Zones 1 to 3: how they feel on a run Zone 1 (50 to 60 percent): breathing is barely elevated. You could carry a full conversation or read aloud. Legs feel fresh even after 30 minutes. This is the pace of a recovery jog or walking a dog. Zone 2 (60 to 70 percent): breathing is noticeable but controlled. You can speak in sentences but would not want to tell a long story. Effort feels sustainable for 60 to 90 minutes. This is the classic aerobic base zone where most easy runs should live. Zone 3 (70 to 80 percent): breathing is heavier, sentences become short answers. You feel like you are working. This is marathon-to-half-marathon race pace for most trained runners. :INFO Zones 4 and 5: the hard end of the spectrum Zone 4 (80 to 90 percent): talking is reduced to a few words at a time. Legs start to accumulate lactate. This is 10K race effort for a trained runner, or the pace of a tempo run. Effort is high but sustainable for 20 to 40 minutes. Zone 5 (90 to 100 percent): conversation is impossible. This is the zone of maximum effort: intervals at 400m to 800m pace, all-out hill repeats, the final 200 metres of a race. Sustainable for 30 seconds to 3 minutes at a time. :INFO A worked example: age 35, using the Tanaka formula Tanaka MHR: 208 minus (0.7 times 35) = 208 minus 24.5 = 183 bpm. Zone 1: 92 to 110 bpm. Zone 2: 110 to 128 bpm. Zone 3: 128 to 146 bpm. Zone 4: 146 to 165 bpm. Zone 5: 165 to 183 bpm. A GPS watch set to Tanaka with an MHR of 183 will display these same numbers. The field test may push this up 2 to 5 beats, which is normal. :LINK https://www.polar.com/blog/running-heart-rate-zones-basics/ Polar: Running Heart Rate Zones Explained :LINK https://therunningchannel.com/running-heart-rate-zones/ The Running Channel: Heart Rate Zones Guide :NOTE Medications such as beta-blockers suppress heart rate and make percentage targets unreliable. If you are on any medication that affects heart rate, use RPE alone and consult a doctor before using HR-based training plans.