400m repeats: 10 x 400 meters fast

Ten fast laps of the track with short jog recoveries, sharpening the top-end speed and leg turnover that easy running never touches.

How to run it

Warm up 15 minutes easy, run 10 x 400 meters fast with a 200-meter jog after each, then cool down for 10 minutes.

The steps above convert 400 meters to roughly 2 minutes and the 200-meter jog to roughly 1 minute, based on a mid-pack pace, about 5:00 per kilometer for the fast reps and an easy shuffle for the jog. That is closer to current 5K effort than a full sprint. Once you have run this session once or twice, use your actual times to fine-tune the pace; the race predictor can also translate a recent mile or 5K time into a 400-meter split.

Effort should sit at RPE 9: fast and controlled, not a maximal sprint. Good form matters more here than at any other distance on this site, quick arms, a slight forward lean, and a relaxed jaw and shoulders. If your form falls apart by rep 6, the pace was too aggressive; ease back slightly and hold it steady for the rest.

A track is ideal because the distance is exact and the effort is easy to judge lap to lap, but it is not required. A flat road, path or field with 400 meters measured by GPS works fine, or run by time using the converted minutes above and adjust once you know your pace.

How to scale it

Easier: 15 min easy, 6 x 400 m fast with 200 m jog, 10 min cool down.

Harder: 15 min easy, 12 x 400 m fast with 200 m jog, 10 min cool down, or step up in distance with 15 min easy, 8 x 600 m fast with 200 m jog, 10 min cool down.

Keep the total fast volume under about 5K worth of reps. Beyond that, quality drops off fast and the session stops training speed.

Common mistakes

• Sprinting rep one and fading by rep five. Even, repeatable splits beat one fast lap followed by a slow fade.
• Cutting the 200-meter jog short. The recovery is what lets you hit the next rep at full quality; rushing it just makes every later rep slower.
• Running this the day after a long run or a hard tempo. Fresh legs matter more for speed work than for almost any other session.

Let the coach schedule it

When TextFit’s coach puts a session like this in your plan, it counts as a hard day: never next to another one, and no more than two a week (three above eight sessions). It reaches your Garmin or Apple Watch as a structured workout with each rep and each jog as its own step and a pace target worked out from your current fitness, and the watch beeps at every change so you can focus on form instead of counting laps. If the day stops working, tell the coach in the chat and it moves or eases the session; every change shows with Undo. Try TextFit free for 14 days on iPhone.