How fast should I run 1km intervals?

Training Paces

AWAndrew WhartonSport scientist and high-level masters runner · AW Run Coach, Wellington · 5 min read

1km reps are the most commonly run interval in distance training, and the pace depends entirely on what you are trying to get out of them.

The short answer

There is no single "1km rep pace". It depends on the session's purpose:

• VO2max reps (5 x 1km, 2–3 min jog): run at about 3km race pace — a little quicker than your current 5km pace.
• Threshold reps (6–8 x 1km, 60–90 sec float): run at threshold pace — what you could hold for about an hour, close to 15km race pace for most trained runners. Noticeably controlled.
• Marathon-support reps (10–15 x 1km, 60 sec float): run at marathon pace.

If someone hands you "1km reps" with no other detail, the honest answer is that the session is incomplete.

Why the answer is "it depends"

A 1km rep is a container, not a session. What goes in it — the pace, the number of reps, the recovery — is what determines the training effect. Five of them at 3km pace and fifteen of them at marathon pace are two completely different workouts that happen to use the same lap distance.

This matters because "1km reps" has become shorthand for "hard running", and a lot of runners default to running them as fast as they can manage. That turns every session into the same session, and a programme where every session is the same session stops working after about six weeks.

The three versions, properly

1. The VO2max version

5 x 1km at 3km race pace, 2 to 3 minutes jog recovery.

This is the benchmark. Around 15 to 20 minutes of work at an effort you could hold for 10 to 12 minutes maximum. The recovery is generous on purpose — it exists so the fifth rep is as quick as the first.

Run this properly and the first two reps should feel almost too easy, the third about right, and the fifth genuinely hard. If rep one is your fastest, start slower next time.

2. The threshold version

6 to 8 x 1km at threshold pace, 60 to 90 seconds float recovery.

This is the version I write most often, and the float is the important part. Instead of jogging or standing, you keep running through the recovery at a controlled aerobic pace. The session stays continuous, the heart rate stays up, and you accumulate 24 to 32 minutes of quality work with none of the stop-start.

Athletes are often surprised by how much more they can do in this format. Someone who struggles through 5 x 1km at 3km pace will comfortably manage 8 x 1km at threshold pace with floats, and will get more out of it.

3. The marathon version

10 to 15 x 1km at marathon pace, 60 seconds float.

Long, monotonous, and one of the best marathon sessions there is. Not hard in any single kilometre — hard by the twelfth. It teaches pace discipline, fuelling under load, and the specific feeling of running marathon pace when you would rather not.

Coach's note

Where you run these changes what you learn from them. On the Newtown Park track the numbers are clean and comparable, which is useful when you want honest feedback. On the waterfront or the Petone Esplanade you get real-world footing and a real headwind, which is closer to racing. Our Saturday club sessions run on the limestone loop at Karori Park across three pace groups, and I like that format for exactly this reason: everyone gets the same rep, on the same surface, with company to hold the pace honest.

One caution if you use Karori Park for kilometre reps, and it matters more than it sounds. The loop is not a kilometre. I have measured it with a calibrated wheel at about 965 metres, and the GPS around that park is unreliable enough that your watch will not tell you. Run 4:00 per lap and it feels like 4:00/km — it is actually about 4:09/km. Over ten laps that adds up. Run to lap time, know your lap distance, and do the conversion honestly. What I would avoid entirely is doing 1km reps on a hilly loop and then comparing the splits to last month. Those numbers mean nothing.

Working out your paces from a recent race

The paces below come from Jack Daniels' VDOT tables — the same model behind the pace calculator on this site, so you can put in your own 5km and get your numbers directly.

5km	VO2max	Threshold	Marathon
25:00	4:45–4:57	5:16–5:31	5:38
22:00	4:13–4:23	4:40–4:54	4:59
20:00	3:51–4:01	4:16–4:28	4:32
18:00	3:29–3:38	3:52–4:03	4:05

All paces are per kilometre, so they are also your 1km rep times on a flat, accurate course: VO2max reps, threshold reps and marathon-pace reps. Notice how close the threshold and marathon columns are, and how big the jump is up to VO2max — that gap is why running every rep "hard" collapses three sessions into one.

Those are starting points, not commandments. Adjust for wind, terrain, how you slept, and where you are in the block.

A progression I use

• Week 1: 5 x 1km at threshold, 90 sec float
• Week 2: 6 x 1km at threshold, 90 sec float
• Week 3: 6 x 1km at threshold, 60 sec float
• Week 4: easier week — 4 x 1km, same pace
• Week 5: 7 x 1km at threshold, 60 sec float

Note what changes and what does not. The pace stays the same. The volume and the density go up. That is what progression looks like — not running each week's session faster than the last.

Recovery: jog, walk, or float?

Float for threshold and marathon-pace work. Keeps the session continuous and the aerobic stimulus high.

Jog for VO2max work. You need the recovery to be genuine so the next rep holds pace.

Standing almost never, in distance training. It is cold, it stiffens you up, and outside of true speed work it usually means the reps are too fast.

How many is too many?

A reasonable ceiling for a single session is around 8 to 10 percent of your weekly volume in hard running. On 60km a week, that is 5 to 6km of quality — so 5 or 6 x 1km at VO2max, or a little more at threshold because it costs less.

If you are running 30km a week and someone has written you 10 x 1km hard, that session is a third of your week's mileage at high intensity. Something is going to give.