The aim of these repetition runs is to learn a specific racing pace and rhythm. How fast you run depends on your target time for a 10K race. The pace you are aiming for is 10% faster than your target race pace. Here's how to calculate this:

Decide your (realistic) 10K target time. Example 42 minutes. This is 2520 seconds.

Take off 10%. This gives 2268 seconds.

There are twenty five 400metres in 10K, so divide 2268secs by 25.

This gives: 91 seconds. This is your target time to average for all the reps in the session.

Recovery is normally 200m jog, & the number of reps 12 to 16. The reps should be controlled fast running, not sprinting. Of course, you need an accurately measured 400m! Some example calculations: