VDOT is one number that describes your running fitness. It gives you the right pace for every training zone, from easy to interval. Here is how it works.
By Alex · 6 min read
Have you ever wondered why one workout leaves you feeling strong while another leaves you broken, even though the two look similar on paper? The answer is usually pacing. More exactly, running at the wrong intensity for what that session is supposed to do.
VDOT fixes this. It gives you one number that describes your current running fitness, and from that number it works out exact training paces for five different zones. No more guessing. No more running your "easy" run at half-marathon effort and then wondering why your legs are dead on Thursday.
VDOT is an idea from the exercise scientist Jack Daniels, whose book Daniels' Running Formula shaped the way distance runners train today. (The capital letters are deliberate. VDOT is not the same as VO2max, although the two are related.)
VO2max is the maximum amount of oxygen your body can use. Measuring it properly needs a lab, a treadmill and a mask. Most runners never have a formal VO2max test.
VDOT skips the lab. It is a number you calculate from a race result. Your time and your distance together give a value that shows your usable aerobic fitness: what you can really do in a race. It includes running economy (how efficiently you run) and all the other things that separate a lab number from real performance.
A 50-year-old who trains consistently may have a lower VO2max than a 25-year-old and still beat them in a race, thanks to better economy, better pacing and a stronger head. VDOT captures that. It measures what you do, not what your body should in theory be able to do.
All you need is a recent race result, at any distance from 1500 m to the marathon.
Enter your time and distance into the VDOT Calculator. It works out your VDOT score and immediately shows:
The calculation uses Daniels' oxygen cost model, an equation, tested against real data, that links running speed to how much oxygen you use.
VDOT gives you five clear training zones, and each one does a specific job in your body:
The foundation zone. Relaxed, conversational running that builds fitness without much stress. Most of your weekly distance belongs here — 70-80% for most runners.
Purpose: build your aerobic base, grow the small blood vessels in your muscles and the energy factories inside your muscle cells, help you recover, and improve your running economy.
Feel: you can hold a full conversation. Your breathing is steady and relaxed.
The pace you could hold for a whole marathon. A controlled effort, but not a comfortable one.
Purpose: teach your body to burn fat at race intensity, and prepare your legs and your mind for marathon effort.
Feel: controlled but serious. You can speak in sentences, but you would rather not.
Also called "tempo pace". It is the fastest pace you could hold for about an hour. At this speed, your body clears lactate as fast as it builds up.
Purpose: raise the speed you can run at while staying aerobic. This helps your racing at every distance.
Feel: "comfortably uncomfortable". You can say a few words, but not a full sentence.
VO2max training. You run at your 3K-5K race effort for 3-5 minutes at a time, with the same amount of recovery in between.
Purpose: increase the maximum amount of oxygen you can use. Raise the ceiling of your aerobic fitness.
Feel: hard. You can say one or two words. Your heart rate is very high.
Short, fast efforts at your mile race pace or faster, with full recovery between them.
Purpose: improve your speed and your running economy, and train your muscles and nerves to work together smoothly.
Feel: very hard, but short — 30 seconds to 2 minutes per rep, with complete rest.
Effort is personal and changeable. A 5/10 effort on a hot, humid Tuesday after a bad night of sleep is not the same, physically, as 5/10 on a cool Saturday morning when you are rested. If you run by feel with nothing to check it against, your paces drift: easy runs get too hard, and hard runs are not hard enough.
VDOT paces are set to what your body can do right now, because they come from a real race result. They match your current fitness — not the fitness you had three months ago, and not the fitness you would like to have, but the fitness you have just proved in a race.
This matters most on easy runs. The VDOT easy pace often surprises runners because it feels too slow. That feeling is a sign the system is working. Easy aerobic running does its work below the lactate threshold, so running harder does not speed up the benefits. It only creates more fatigue.
VDOT is not fixed. As you train, race and adapt, it goes up. A VDOT of 40 in January might be 44 by June if you train consistently and race.
When your VDOT rises, all of your training paces get faster too. That is why it is worth re-testing yourself with a tune-up race every 6-8 weeks. If you train at old paces, you either run too slowly (and miss the benefit) or too hard (and collect extra fatigue).
The VDOT What-If Explorer lets you move the VDOT value up and down and see what the training paces and race predictions would look like at a higher score. It is useful for setting realistic targets.
Some coaches set training zones by pace alone: run your easy runs at X:XX/km and your tempo runs at Y:YY/km. That works if those paces match your fitness. The problem is that they often do not, or nobody updates them when your fitness changes.
VDOT solves both problems. The first setting comes from a real race, and updating it only takes a new race result.
Done properly, the two methods end up in the same place. VDOT is simply a clear method for getting the right paces from real data.
The first time you look at your VDOT easy pace and realize that you have been running your easy days 90 seconds per kilometer too fast, everything makes sense. The training starts to fit together. The improvement follows.
Calculate your VDOT →
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