Every training pace in Sequorr — your easy runs, your tempo sessions, your intervals — comes from a single number: your VDOT. It's a fitness score derived from a race result using equations published by exercise physiologist Jack Daniels. Give the system a recent race time and it gives you back five training paces, each targeting a specific physiological adaptation. No guesswork. No arbitrary zones. Just math calibrated to where your fitness actually is.
This article explains what VDOT is, how the equations work, what the five training zones mean, and how Sequorr turns a race result into a full weekly training plan.
What VDOT Actually Is
VDOT is not VO2max — though it's related. VO2max is the maximum volume of oxygen your body can use during exercise, measured in a lab. VDOT is a pseudo-VO2max that estimates your effective aerobic fitness based on how you actually perform in a race. Two runners with identical lab VO2max values can have different VDOTs because VDOT captures the factors that lab tests miss: running economy, lactate clearance, pacing ability, and race-day execution.
This makes VDOT more useful than VO2max for training purposes. It reflects what you can actually do on the road, not what your body can theoretically produce on a treadmill with a mask on your face. For most runners, VDOT falls between 30 and 85. A recreational runner finishing a 5K in 30 minutes has a VDOT around 30. A sub-3:00 marathoner is in the mid-50s. An elite 5K runner breaking 14 minutes is above 70.
How VDOT Is Calculated
The calculation takes two inputs: a race distance and the time you ran it in. From those, two intermediate values are computed using Daniels' empirical curve fits.
Step 1: Oxygen cost at race pace
Given your race velocity (distance divided by time, in meters per minute), the oxygen cost of running at that speed is:
Step 2: Sustainable fraction of VO2max
No one can hold 100% of their VO2max for an entire race. The fraction you can sustain decreases as race duration increases. Daniels modeled this decay as a double exponential:
Step 3: VDOT
VDOT is simply the oxygen cost divided by the sustainable fraction:
This is the number Sequorr stores on your profile. It's recalculated whenever you enter a new race result, and it drives every training pace in the app.
The Five Training Zones
Once Sequorr has your VDOT, it derives five training paces by reversing the equations. Each zone targets a specific %VO2max range. The app solves the oxygen cost equation backward — given a target VO2 output, it finds the velocity that produces it, then converts that velocity to a pace per mile or kilometer.
Easy (E) — 59-74% VO2max
This is where most of your weekly mileage should happen. Easy pace builds aerobic base: capillary density, mitochondrial development, fat oxidation efficiency. It should feel genuinely easy — conversational, relaxed, sustainable for hours. If you're breathing hard, you're above Easy pace.
For a VDOT of 45, Easy pace is roughly 9:50 to 10:30 per mile.
Marathon (M) — 75-84% VO2max
Marathon pace is what it sounds like — the pace you'd target for a marathon. It trains your body to burn fat efficiently at a sustained moderate intensity and builds confidence in race-specific effort. It's harder than Easy but still controlled. You should be able to hold it for 2-3+ hours.
For a VDOT of 45, Marathon pace is roughly 8:50 per mile.
Threshold (T) — 83-88% VO2max
Threshold pace sits right at your lactate threshold — the fastest pace you could sustain for approximately 60 minutes in a race. It trains your body's ability to clear lactate. The classic threshold workout is a 20-minute tempo run or cruise intervals (3-4 repeats of 1 mile with 1 minute recovery). It should feel "comfortably hard" — not easy, not all-out.
For a VDOT of 45, Threshold pace is roughly 8:10 per mile.
Interval (I) — 95-100% VO2max
Interval pace stresses your aerobic system at its maximum to drive VO2max higher. These are hard efforts — 3 to 5 minutes at near-maximum aerobic intensity with recovery jogs between reps. A typical session: 5 x 1000m at I-pace with 3 minutes of easy jogging between reps. You should be working hard but able to complete every rep at the same pace.
For a VDOT of 45, Interval pace is roughly 7:30 per mile.
Repetition (R) — 105-120% VO2max
Repetition pace is faster than VO2max intensity — it's anaerobic. These short, fast efforts (200m to 400m) improve running economy, neuromuscular coordination, and raw speed. Recovery between reps is full — you should feel ready to run the next one at the same quality. This isn't about suffering through fatigue. It's about moving fast with good mechanics.
For a VDOT of 45, Repetition pace is roughly 7:00 per mile for 200-400m repeats.
How Sequorr Uses VDOT
The VDOT screen
In Sequorr, you access VDOT from your profile (prominent for Road Running profiles, accessible in training tools for other profiles). You select a race distance — 5K, 10K, Half Marathon, or Marathon — then scroll to your finish time. The app computes your VDOT instantly and displays all five training paces in a zone card layout, color-coded from green (Easy) through red (Interval) to pink (Repetition).
A slide-to-confirm action locks in your VDOT and pushes you to the Weekly Plan Builder.
The Weekly Plan Builder
Once your VDOT is set, Sequorr generates a Daniels-style 7-day training week. The default template follows a classic structure: Monday easy, Tuesday threshold, Wednesday recovery, Thursday intervals, Friday rest, Saturday long run, Sunday easy shakeout. Every session's distance and pace is auto-derived from your VDOT and profile.
But this isn't a rigid plan. You can tap any day and swap the session type from a grid of seven options: Easy, Long Run, Threshold, Intervals, Marathon Pace, Repetition, and Rest. When you change the type, the distance and pace recalculate automatically. The week summary updates live — total run days, total miles, rest days.
Save the plan and it persists to your profile. On the Activity screen, a training card shows today's planned session — the type, the distance, and the target pace. Tap it to expand and see the full week at a glance.
Race equivalents
VDOT also predicts equivalent race performances. If you ran a 20:00 5K, Daniels' equations can estimate your equivalent 10K, half marathon, and marathon times — assuming equal fitness across distances. These predictions appear in the VDOT detail screen and help you set realistic race goals based on where your fitness actually is.
VDOT and Training Profiles
VDOT doesn't appear the same way for every athlete. Sequorr's training profile system determines where and how VDOT surfaces based on how relevant it is to your training:
- Road Running — VDOT is prominent. The training card on your dashboard shows today's VDOT session. The weekly plan builder is a core feature. This profile was built for VDOT.
- Trail Running — VDOT is secondary. Trail pace varies too much with terrain for pace-per-mile targets to be reliable. VDOT lives in training tools, not the main dashboard. It's still useful for estimating road-equivalent fitness, but it's not the primary training signal.
- Triathlon — VDOT surfaces only in run-specific contexts. It's relevant for the run leg but not for cycling or swimming. When you're looking at run training, it's there. Otherwise, it stays out of the way.
- General Endurance — VDOT is hidden until you've logged enough runs to make it meaningful. After 5+ runs, Sequorr surfaces it contextually. For athletes who aren't chasing race times, pace zones add complexity without clear benefit.
The Math Is Open, The Implementation Is Free
Daniels published these equations decades ago. They're in his book. They're on running forums. The formulas are not proprietary. What most platforms do is implement them and charge you to see your own paces — often as part of a premium subscription tier.
Sequorr's VDOT calculator runs both client-side (for instant reactive UI) and server-side (for plan generation and backend validation). The client-side implementation in Flutter mirrors the backend Node.js equations exactly. When you scroll your race time and watch the VDOT update in real-time, that's the Daniels equations running on your phone, not a server call.
It's free. Like everything else in Sequorr, the VDOT calculator, the pace derivation, and the weekly plan builder are core features available to every user. No premium tier. No paywall between you and your training paces.
