Sub-20 is the one. More people are stuck at 20:30 than any other number in running. Every Saturday. 20:15, 20:08, 20:02. Home fuming.

I know because I did exactly that. September 2013 to January 2014 to get under it, with weeks of 20:01 and 20:02 on the way.

Then it came. 19:39. And after that a run of PBs at the end of February: 19:20, 19:19, 19:09, 18:46.

They cluster like that. You batter at the door for months and then it opens and keeps opening.

What it takes

6:26 a mile, three times, plus a bit. 3:59 a kilometre if you think that way.

25 to 35 miles a week gets most people there. It’s not a mileage problem at this level, it’s speed and pacing. Good news, because both fix quicker than endurance does.

The three sessions

Intervals at goal pace. 6 to 8 x 800m at 3:12, which is bang on 6:26 pace, 90 seconds jog between. Build to 10 over a few weeks. Teaches your legs the pace when you’re tired, which is the whole problem on a Saturday.

Threshold. 20 minutes continuous at about 6:50. Comfortably hard, the pace you’d hold for an hour if you had to. This raises the ceiling and it’s the one most people skip, because it isn’t fun and it isn’t fast.

Hills. 8 to 10 x 45 seconds hard up a decent drag, jog down. Sadistically tough and worth every second. Strength and speed at once without the pounding of flat intervals.

Two a week. Never three. Everything else easy.

Pacing, where most people lose it

The classic sub-20 attempt goes 6:05, 6:35, 6:45. First mile too fast on adrenaline and a downhill start, dying from there.

You want 6:26, 6:26, 6:26 and whatever’s left. Or negative if you can hold your nerve. 6:30, 6:25, 6:20.

That first mile discipline is the single biggest thing between you and sub-20. It’ll feel far too easy. Let it.

Pick your course

Not all parkruns are the same and anyone telling you otherwise hasn’t run Barnsley. My parkrun best sits at 15:40 and I’ve never got close to it at my home one. Same legs. Different course.

Within ten seconds of it? Go and tourist somewhere flat. No shame in that, though I’ll admit I always felt it didn’t quite count until I’d done it at home.

When it doesn’t come

Don’t go for it every week. Race it properly once a month, run the rest steady. Otherwise you’re stacking up hard efforts and never freshening enough to actually do it.

Four months of 20:0x for me. Then four PBs in four weeks.

Keep turning up.

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