Each repeat is meant to get a little faster, so your two-minute hills feel like tempo and those last 15-second hills should feel almost all-out. All the recovery is jogging back down to your start line. This continuous effort helps you battle through when things get tough between the 15 km and 18 km marks in the half-marathon.
For me, this a 10- to 15-minute routine done before my warmup, including active isolated stretching, cat/cows and single-leg Romanian deadlifts
10–20 minutes of jogging
2 x 2 minutes 2 x 90 seconds 4 x 60 seconds 4 x 30 seconds 4 x 15 seconds
10–20 minutes of jogging, plus drills (glute band work, A, B and C skips)
Static stretching, plus a snack. (My hips tend to get tight, so I do some seated leg hugs, like they do at the end of a yoga class, and I also roll my hips with a lacrosse ball.)