VO2 Max Training Zones Calculator

Training zones divide exercise intensity into bands, each producing a different physiological adaptation. The catch is that there are two different ways to draw the lines, and they do not land in the same place.

Percent of maximum heart rate, and why it is the weaker method

The familiar zones are percentages of maximum heart rate. They are easy, and they systematically overstate how hard you are working, because your heart is already beating at rest. At 60% of a maximum of 185 you are at 111 bpm, and if your resting rate is 60 then you are only about 41% of the way from rest to flat out. That is a warm-up, not an aerobic base session.

Percent of VO2 reserve, using heart rate reserve

The better method uses heart rate reserve, the span between your resting and maximum pulse:

Target = resting HR + intensity × (max HR − resting HR)

This is the Karvonen formula, and it belongs on a page about VO2 max because percent of heart rate reserve tracks percent of VO2 reserve almost one for one. VO2 reserve is the same idea for oxygen: the span from what you use sitting still to your VO2 max. Swain and Leutholtz showed this in 1997, and the title of their paper says the rest: heart rate reserve is equivalent to %VO2 reserve, not to %VO2max. The American College of Sports Medicine has written its intensity guidelines in VO2 reserve since.

The difference only matters at the easy end. Resting oxygen use, about 3.5 mL/kg/min, is a bigger share of a small number, so 50% of heart rate reserve is a little over half of VO2 max, while 90% of it is close to 90% of VO2 max. Either way, a zone written in percent of VO2 reserve turns straight into a heart rate you can read off a watch, built on your own resting pulse instead of an average one.

For a 35-year-old with a resting pulse of 55 and a maximum of 184, the two methods put the bottom of Zone 2 at 110 bpm and 132 bpm respectively. Twenty-two beats apart, on the zone people spend the most hours in.

The 5 zones, by percent of VO2 reserve

• Zone 1 (50-60%): active recovery. Genuinely easy. Warm-ups, cool-downs, the day after a hard session.
• Zone 2 (60-70%): aerobic base. Conversational, and the foundation of endurance training. Much of the build-up in mitochondria and capillaries comes from the sheer hours spent here.
• Zone 3 (70-80%): tempo. Moderately hard. The most common training error is living here, too hard to recover from and too easy to drive adaptation.
• Zone 4 (80-90%): lactate threshold. Short sentences only. Raises the pace you can hold for a long time. The 10K and half-marathon zone.
• Zone 5 (90-100%): VO2 max and neuromuscular. Minutes at a time at most. Top-end speed and maximal oxygen uptake.

Estimating maximum heart rate

The classic MHR = 220 − age is still everywhere and it is not very good: it overestimates the young and underestimates the old, with a standard deviation around 10 beats. Tanaka’s MHR = 208 − (0.7 × age) fits the population better and is the default here. Neither beats an actual measurement from a hard field test, so if you have a real number, use it.

Worked example

A 35-year-old, Tanaka maximum 184 bpm, resting 55 bpm. Heart rate reserve is 129.

Zone 2 by heart rate reserve: 55 + 0.60 × 129 = 132 bpm at the bottom, 55 + 0.70 × 129 = 145 at the top.
Zone 4: 55 + 0.80 × 129 = 158 to 55 + 0.90 × 129 = 171.

The same zones as bare percentages of maximum would read 110 to 129 and 147 to 166. If you have ever wondered why easy runs feel so slow when you follow a watch’s default zones, this gap is usually why.

Your data stays in your browser. We do not store, collect, or transmit any information you enter.