How this calculator works
The page uses the Jack Daniels and Jimmy Gilbert model. Your race pace gives the oxygen cost of running through the equation VO2 = -4.60 + 0.182258 v + 0.000104 v squared, where v is metres per minute. A race of a given duration can be sustained at a predictable share of maximum oxygen uptake, which is subtracted to give VDOT, a fitness score in millilitres per kilogram per minute. Each training zone is a share of that VDOT. Solving the oxygen-cost equation backwards for the share gives the velocity, and the velocity gives the pace. Easy and long runs use the aerobic end, threshold work sits near the lactate threshold, and interval and repetition work reach close to or above VO2 max.
Formula
VO2 (mL/kg/min) = -4.60 + 0.182258 v + 0.000104 v squared, with v in m/min. Sustainable share = 0.8 + 0.1894393 e^(-0.012778 t) + 0.2989558 e^(-0.1932605 t), with t in minutes. VDOT = VO2 / share. Training pace for a zone = 60000 / v, where v solves the oxygen equation at the zone share of VDOT. Zone shares used here: long run 62 percent, easy 70 percent, marathon 80 percent, threshold 85.5 percent, interval 97.5 percent, repetition 107 percent.
Worked example
A 50:00 10 km is 200 m/min for 50 minutes. The oxygen cost is -4.60 + 36.4516 + 4.16 = 36.01 mL/kg/min, and the sustainable share is 0.900, so VDOT is about 40.0. Easy pace at 70 percent needs an oxygen uptake of 28.0, which solves to about 163.6 m/min and a pace of 6:07 per kilometre. Threshold pace at 85.5 percent solves to about 191.9 m/min, or 5:13 per kilometre. Repetition pace at 107 percent solves to about 230 m/min, or 4:21 per kilometre.
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Frequently asked questions
Which race should I use for VDOT?
Use the fastest recent race that was properly paced and run in reasonable conditions, ideally within the last four to eight weeks. A shorter race is less affected by fuelling and heat, but it should be a real race effort rather than a solo time trial.
Why is there a separate long run pace?
Long runs are usually run a little slower than the easy band to keep the effort aerobic and to limit fatigue. The page places the long run at 62 percent of VDOT and easy at 70 percent, so the two are close but distinct.
What if my race was much faster than my training suggests?
That is the point of using a race. VDOT reflects current fitness, not the pace you usually train at. If the race was a one-off in ideal conditions, use a slightly lower VDOT for training so the sessions stay achievable.
Does the model work for treadmill running?
It assumes flat, still-air running and does not adjust for the treadmill belt, incline or indoor heat. Set the incline to one percent for a closer outdoor match, and treat the paces as a guide rather than an exact prescription.