Research · 3 min read · 2026-10-15
What do hill intervals do?
Six weeks of uphill intervals improved 5 km times by 2 percent in well-trained runners, whatever the programme.
Hill repeats are a classic part of distance running. They work the legs like strength training while you run. A study from New Zealand tested different ways of doing them.
What the researchers did
Twenty well-trained runners were randomly given one of five uphill interval programmes, from shorter and very hard to longer and more moderate. They trained for six weeks. Before and after, the researchers tested a 5 km time trial, running economy and jumping power.
What they found
The 5 km time improved by 2.0 percent on average, and there was no clear best programme. The hardest programme gave the largest improvement in running economy, 2.4 percent, and in jumping power.
What it means for you
Hill intervals are a good way to train, and you don't need a precise formula. Short, hard hills mainly build power and economy. Longer hills at a slightly lower effort train more of your endurance.
Uphill, pace says little about effort. Run by how hard it feels and how you breathe, and jog or walk down easily so you are ready for the next repetition.
What the study can't tell you
With 20 runners split between five programmes, each group was small. The study lasted six weeks and included well-trained runners.
How we use it
Hill sessions in PX7 Training are guided by effort, not by your flat-ground pace. Recovery down the hill is part of the session.
Source
- Barnes et al. (2013), Effects of different uphill interval-training programs on running economy and performance. International Journal of Sports Physiology and Performance.
Written by Jørgen Larsen for PX7 Training.