Training pace zones — explained without the jargon

Updated April 28, 2026 · 12 min read · by Samuel Yoo

Most beginner training plans throw five terms at you on day one — easy pace, marathon pace, threshold, interval, repetition — and assume you know what they mean. You don’t, and the plan doesn’t really tell you, and so you run all of them somewhere between “kinda hard” and “really hard,” and you wonder why you’re not improving.

The pace zones aren’t arbitrary. Each one drives a specific physiological adaptation. Run them at the wrong intensity and you get none of the benefit but all of the fatigue. Worse, you can’t tell from inside the run — the difference between “threshold” and “interval” feels similar; the difference is in what your body does the next 24 hours.

This is the explainer I wish I’d had on day one.

The five zones, in one sentence each

Most runners spend too much time at threshold/marathon (“comfortably hard” feels productive) and too little at easy (“doesn’t feel like training”). The fix is almost always: run easier on easy days, harder on hard days.

Easy pace — the misnamed zone

If you’re putting in real effort on your easy run, it’s not an easy run. The point of the easy run isn’t fitness, it’s recovery while still accumulating mitochondrial volume. Your body builds capillaries and aerobic enzymes at low intensity, and only at low intensity, and those structural adaptations are what allow harder workouts to actually improve you.

How fast? 5K race pace + 90–120 seconds per km, slower. If your 5K is 22:30 (4:30/km), your easy pace is 6:00–6:30/km. That feels too slow. That’s the point.

Some heuristics:

• The conversation test. You should be able to hold a conversation in full sentences. If you’re talking in fragments, you’re too fast.
• Heart rate. 65–75% of max HR. For most adults, this puts you in zone 2 on a 5-zone Garmin or Polar.
• Nasal breathing. If you can run with your mouth closed, it’s easy.

If your “easy run” is making you tired by the end of the week, it’s not easy enough. Slow down. This is the most common single mistake in amateur training.

Marathon pace — your actual race-day pace

Marathon pace is what it says on the tin: the pace you’d run a fresh marathon at. For someone targeting a 3:30 marathon, that’s 4:58/km. For 4:30 it’s 6:24/km.

The training purpose is twofold:

1. Fueling rehearsal. At marathon pace, your body burns mostly fat with some glycogen. Practising at this exact pace teaches the body when to switch fuel sources and how to absorb gels mid-effort.
2. Mental rehearsal. Marathon pace feels deceptively easy in training and brutally hard at km 32 of a race. Long runs with marathon-pace segments at the end (e.g., the last 8 km of a 30 km run) train you to hold pace when tired.

Frequency. Once a week max in the 8–12 weeks before a marathon. Outside of race builds, skip it — there’s no aerobic adaptation specific to marathon pace that you don’t get more efficiently from threshold.

Threshold pace — the one that pays the most per minute

Of all the workouts, threshold gives the highest return on training time for distance runners. It’s the pace at which your blood lactate starts accumulating faster than you can clear it — about 10K race pace for most runners, or 5K pace + 15–20 sec/km.

Why it matters: lactate isn’t a waste product, it’s a fuel. The faster you can clear and reuse it, the higher pace you can sustain aerobically. Threshold work shifts that lactate-clearance ceiling upward, which raises every pace below it. Your easy pace gets faster. Your marathon pace gets faster. Your 5K gets faster. One workout, many wins.

Format. Total volume of 20–40 minutes at T pace, broken into chunks that don’t exceed your sustainable duration:

• 4 × 6 min @ T with 90 sec rest (24 min total)
• 3 × 10 min @ T with 2 min rest (30 min total)
• One continuous 20 min tempo

The pace should feel “comfortably hard.” You can talk in 5-word fragments, not full sentences. By the end of the rep, you should feel like you could do another one but wouldn’t want to.

Interval pace — VO2max work

Interval pace is faster than threshold — usually 3K–5K race pace. Repetitions of 3–5 minutes at this intensity, with similar-duration rest, push your aerobic ceiling. Over weeks, your VO2max (maximum oxygen uptake rate) improves.

Format. 3–5 minutes per rep, equal rest:

• 5 × 1000m @ I pace with 2 min rest
• 6 × 800m @ I pace with 90 sec rest
• 4 × 1200m @ I pace with 3 min rest

The pace should feel uncomfortably hard. By the third rep, you’re questioning your life choices. By the last, you can barely speak.

If you can talk in fragments during the rep, you’re not at I pace — you’re at threshold. If you can barely jog through the rest, you started too fast.

Repetition pace — the speed work runners skip

Repetition pace is mile race pace or faster — fully anaerobic, run for short reps with full recovery. It builds raw speed, neuromuscular coordination, and running economy (the efficiency of your stride).

Format. 200–400m reps with full recovery (3–5× the rep duration):

• 8 × 200m fast with 200m walk
• 6 × 400m fast with 400m walk
• 5 × 300m fast with 300m walk

The pace is “fast but controlled” — not an all-out sprint, but distinctly anaerobic. Recovery is so generous because the goal isn’t cardiovascular load, it’s stride mechanics.

Most distance runners skip R-pace work. They shouldn’t. Fifteen minutes of R-pace per week makes every other pace feel easier through improved running economy.

How to actually find your paces

The easy way: plug your most recent honest race time into the pace calculator → “Predict race” tab → and read off these targets:

• For an X-K race time, your easy pace is roughly X-K pace + 90 sec/km
• Marathon pace is X-K pace × 1.06^(42.195/X)^0.06 — but you can just plug 42.195 km into the predictor
• Threshold ≈ predicted 10K pace
• Interval ≈ predicted 3K–5K pace
• Repetition ≈ predicted mile pace

The hard way: Daniels VDOT tables. Jack Daniels’ Running Formula publishes lookup tables that give exact paces from VO2max equivalent times. The pace calculator approximates the same logic.

Which zones to actually run

For a marathoner in race build:

Mon: rest or 30 min easy
Tue: T workout (e.g., 4×6 min @ T)
Wed: easy 60 min
Thu: easy 45 min + R strides at the end
Fri: rest or easy 30 min
Sat: long run with M-pace segment (e.g., 28 km with last 8 km @ M)
Sun: easy 60 min

For a 5K/10K runner:

Mon: easy 30 min
Tue: I workout (e.g., 5×1000m @ I)
Wed: easy 45 min
Thu: T workout (e.g., 3×10 min @ T)
Fri: easy 30 min or rest
Sat: long run easy 90 min
Sun: easy 45 min + strides

Notice both plans have two hard days plus one long run, with everything else easy. That’s the structure. The specific paces matter less than getting the easy days actually easy.

Three signs you have the paces wrong

1. You’re tired all the time. Easy days are too fast.
2. You don’t improve in races despite training hard. Easy days are too fast and you’re chronically under-recovered for the hard days.
3. Your hard days feel like a slog, not a session. You’re at threshold every time you “go hard” — never reaching interval. You’re missing VO2max stimulus.

The fix for all three is the same: slow down on easy days, separate the intensities clearly, run T at T and I at I.

TL;DR

Five paces, five different physiological purposes:

• Easy — recovery + mitochondria. Too slow feels right.
• Marathon — fueling + mental rehearsal. Race-specific.
• Threshold — lactate clearance. Highest ROI per minute.
• Interval — VO2max. Hard.
• Repetition — speed + economy. Short, fast, full recovery.

Plug your race times into the pace calculator to find each one. Run them as written. Stop running threshold every time you “go hard.” Slow down on easy days. The improvements come from following the prescription, not from running harder.