Niels Laros posted a workout on Strava from the other day. Hills + track.
10 sets of 300m hill, jog down recovery, 100m hill, walk down.
8 minute jog to the track
5 x 300 in 45 with 100m jog
8 minutes
5 x 300 in 42 with 90s 300m jog
6 minutes
3 x 200 (3:00) in 24
Fast running. Especially those 200s after a big volume of fast work.