Why your training paces come from one race result
The single most common training error is running the easy days too hard, and this framework exists largely to stop it.
6 min read
How are VDOT training paces calculated?
A recent race result is converted into an estimate of your current aerobic fitness, expressed as a single number. Training paces are then derived from that number as fixed proportions of the effort it represents — easy, marathon, threshold, interval and repetition. Because every pace comes from the same estimate, they stay internally consistent, and updating one race result updates all of them.
One number, five paces
The approach starts from a recent race performance, ideally within the last few weeks and over a distance you raced hard.
That result is converted into an estimate of current fitness. Every training pace is then a defined proportion of the effort associated with that estimate, so the paces are consistent with each other by construction rather than by guesswork.
The practical benefit is that you cannot accidentally set a threshold pace that is inconsistent with your interval pace. Both come from the same source.
It also means a stale race result produces paces that are all wrong in the same direction, which is easier to spot than paces that are individually wrong.
What each zone is actually for
The zones are not arbitrary gradations of effort. Each targets a different adaptation.
Easy pace builds aerobic base and capillary density, and it is where most weekly volume should sit. Marathon pace rehearses race effort and fuelling. Threshold pace sits around the point where lactate begins accumulating faster than it clears, and raising that point is the single most trainable determinant of distance performance.
Interval pace targets maximal aerobic capacity. Repetition pace targets running economy and speed, and is short enough that it is not primarily an aerobic session at all.
Running a session at the wrong pace does not just make it harder — it trains something other than what the session was for.
The easy-day mistake
This is the error that undoes more training plans than any other. Easy runs get run too fast.
It feels productive. It is not. Easy pace is deliberately slow enough to be sustainable at high weekly volume, and running it faster produces fatigue that degrades the hard sessions where the adaptation actually happens. The result is a runner who is permanently moderately tired and improving slowly.
Many experienced coaches consider the discipline to run easy days genuinely easy to be the hardest thing to teach.
If your easy pace feels embarrassingly slow, that is usually a sign it is correct.
The estimate is only as fresh as the race
The whole framework depends on the input being current. A race from six months ago describes six-month-old fitness.
Re-test periodically — a hard time trial or a low-key race every four to six weeks is enough — and update your paces. Training to paces derived from fitness you no longer have is either too hard, which invites injury, or too easy, which stalls progress.
Be honest about the effort, too. A race run at 90% effort produces an underestimate and paces that are too soft.
Environmental conditions matter as well: a hot or windy race understates fitness, and altitude changes the picture again.
Paces are a starting point, not a prescription
The estimate assumes a typical relationship between race performance and physiology. Individuals vary.
Some runners are naturally better at shorter distances and find the derived marathon pace optimistic; others are the reverse. Terrain, heat, humidity and fatigue all shift what is appropriate on any given day.
Use the paces as a well-founded starting point and adjust from experience. A framework that tells you roughly where each session should sit is enormously more useful than no framework — but it does not know how you slept.
If a prescribed pace consistently feels wrong across several sessions, trust the pattern and adjust.