Guide
Running Training Pace Zones Explained
Running every session at the same "medium-hard" effort is the most common way to plateau. Structured training uses pace zones — different speeds for different purposes — so that easy days are truly easy and hard days are genuinely hard. Get the split right and your body adapts faster; get it wrong and you spend months accumulating fatigue without the fitness to show for it.
The five training paces
- Easy — conversational, the bulk of your weekly mileage; builds aerobic base, grows capillary density and mitochondria, and aids recovery between harder sessions. This is where most of your adaptation actually happens, precisely because it's unglamorous.
- Marathon — comfortably hard, the pace you could hold for a marathon. It trains your body to burn fat efficiently and clear waste products at a sustainable rate over long durations.
- Threshold — "comfortably uncomfortable," around the effort you could sustain for about an hour; improves your lactate threshold, the pace at which lactate starts accumulating faster than you can clear it. Raising this pace is one of the most reliable ways to get faster across every distance from 10K to marathon.
- Interval — hard, roughly 3–5 minute repeats with recovery jogs between; develops your VO₂ max, the ceiling on how much oxygen your body can use per minute. These sessions feel taxing but are short enough that the total hard-running volume stays manageable.
- Repetition — very fast, short reps (200m–600m) with full recovery; sharpens speed, running economy and neuromuscular coordination rather than any single energy system.
Each zone trains a different physiological lever. Skip one and you leave an adaptation on the table; do all of one and skimp on the others and you'll hit a ceiling — fast without endurance, or durable without top-end speed.
The zones as a percentage of threshold pace
StrideForever's training pace zones calculator derives all five zones from a single number — your threshold pace — using fixed multipliers. Here's exactly how each zone relates to threshold (100%): a smaller percentage means a faster pace (fewer seconds per kilometre), a larger percentage means a slower pace.
| Zone | % of threshold pace | What it feels like | Typical session |
|---|---|---|---|
| Easy | 120–140% | Fully conversational; you could hold a conversation without gasping | 30–90 minutes steady, most days of the week |
| Marathon | 105–110% | Comfortably hard; a few sentences at a time, not a full chat | 20–40 minutes continuous, or long-run finishing miles |
| Threshold | 98–102% | "Comfortably uncomfortable"; short phrases only | 2–3 × 10–15 minutes, or one 20–30 minute tempo, with short jog recoveries |
| Interval | 90–95% | Hard; single words only, breathing heavily | 5–8 × 3–5 minutes with equal-time jog recovery |
| Repetition | 85–90% | Very fast, sharp; near sprint effort but controlled | 6–10 × 200–400m with full recovery between reps |
Those percentages are the exact multipliers the calculator applies — they're not rounded approximations, so plugging your threshold pace into the tool will reproduce the ranges above precisely.
Find your threshold pace
The most practical proxy for threshold pace is a recent race result over a distance you can hold for roughly 40–60 minutes — for most runners that's somewhere between 10K and 15K. StrideForever's calculator takes threshold pace as its single input, so if you don't already know it, use your race pace directly: divide your finish time by the distance.
Worked example: threshold pace from a 10K in 47:30
Suppose you raced a 10K in 47:30. Your average race pace is:
47:30 ÷ 10 km = 4:45 /km.
Because a 10K sits squarely in the "about an hour" window, we treat that race pace itself as your threshold pace — there's no extra conversion step. Feeding 4:45 /km into the calculator's multipliers gives you these five ranges:
| Zone | Pace range (per km) |
|---|---|
| Easy | 5:42–6:39 /km |
| Marathon | 4:59–5:14 /km |
| Threshold | 4:39–4:51 /km |
| Interval | 4:17–4:31 /km |
| Repetition | 4:02–4:17 /km |
Notice how wide the easy range is compared to threshold or interval — that's deliberate. The harder zones need tighter control because small pace errors compound quickly over a rep; easy running has a much wider "good enough" band, which is exactly why so many runners default to running it too fast.
Week structure: the 80/20 idea
A well-known guideline is that around 80% of your weekly running time should be at easy effort, with only about 20% at threshold pace or faster. Picture a runner doing five sessions a week: four of them — the bulk of the volume — sit in the easy zone, and just one session carries the threshold, interval or repetition work. That single hard day (or occasionally two, for more experienced runners) is where the fitness-driving stress comes from; the other four days exist to let you absorb it without breaking down.
Most runners do too much of their easy running too fast, which blunts recovery and leaves them flat for the sessions that actually drive improvement. Slowing the easy days down is often the single biggest change a runner can make — read why most of your running should be easy for the full case on why the 80/20 split works and how to hold yourself to it on easy days when it feels too slow.
A simple week that respects this split, for someone training for a road race:
- Monday — easy 40 minutes
- Tuesday — threshold: 3 × 10 minutes at threshold pace, 2 minutes easy jog between
- Wednesday — easy 30–40 minutes, or rest
- Thursday — interval: 6 × 4 minutes at interval pace, equal-time jog recovery
- Friday — rest or very easy 20–30 minutes
- Saturday — easy 30 minutes
- Sunday — long run, easy to marathon effort, building duration over weeks
Count the minutes and the hard work (Tuesday plus Thursday) comes to a fraction of the week's total time — usually landing close to that 20% mark once the long run and easy days are added up.
Set your zones
Enter your threshold pace into the training pace zones calculator and it returns easy, marathon, threshold, interval and repetition ranges — so every run has a clear target. Not sure of your current threshold pace? Work it out from a recent race or hard effort with the pace calculator.
Common mistakes
- Training in the gray zone. The single biggest error in distributed training is drifting into the "medium" pace between easy and threshold — too fast to recover from, too slow to meaningfully raise your threshold. It feels productive because it's hard enough to be tiring, but it delivers the worst of both worlds: accumulated fatigue without a clear physiological stimulus. If a session doesn't have a specific zone target, it tends to default here.
- Setting zones from a max-heart-rate formula. Age-based formulas like 220 minus age are population averages with wide individual error bars — two runners of the same age can have max heart rates 20+ beats apart. Zones built on a guessed max HR can be badly miscalibrated, sending you too easy or too hard without you realizing it. Pace zones anchored to a real, recent race result are far more reliable than heart-rate zones anchored to an estimated formula.
- Never re-testing threshold pace. Threshold pace shifts as fitness changes — sometimes by 10–20 seconds per kilometre over a training block. Zones set from a race six months or a year ago can be stale, especially after a solid training block or a long break. Re-check your threshold every 8–12 weeks, or after any race that gives you a fresh data point, and update your zones accordingly.