tempo run

One of the best ways to become a faster runner is… to run faster. Darn it, why is there never a short cut?

A tempo run is performed at a quicker pace than usual, but unlike a sprint you should be able to keep the pace up for a few miles. The phrase ‘comfortably hard’ gets mentioned a lot.

Tempo runs will help increase the point at which you’d usually crash and burn, meaning you’ll be able to run faster with less effort in the future.

It's also known as a lactate-threshold, LT, or threshold run.