Hill Training for Runners: What the Research Shows

Does hill training actually improve running performance?

The controlled evidence is encouraging, particularly for uphill interval work. Barnes et al. (2013) randomised well-trained distance runners to different uphill interval programmes over six weeks and found that 5-km running economy improved, with the highest-intensity uphill intervals clearly optimal (economy improved by roughly 2.4%). Time-trial performance improved by a mean of around 2% across all the intensities tested, suggesting that any high-intensity uphill interval work benefits 5-km performance.

Alemu et al. (2025) extended this to moderately trained 16-20 year-old middle-distance runners. Over eight weeks, the steepest gradient (~7.6%) produced the greatest, statistically significant improvements in maximal velocity, 800 m time-trial performance and strength endurance versus a control group. Both trials are randomised, which strengthens confidence. The caveats are that sample sizes are modest and the populations are specific, so effect sizes for recreational runners over longer distances are less certain.

Why does running uphill help?

The mechanism is largely mechanical and metabolic. Vernillo et al. (2017), in a narrative review, describe how uphill running raises metabolic cost, oxygen uptake and cardiovascular demand while shifting gait toward higher cadence, shorter stride and predominantly concentric muscle work. In effect, the slope forces the runner to produce more force per stride at a controlled speed, without the heavy impact loading of downhill or fast flat running.

That force demand is why uphill work is often framed as a bridge between running and strength training. Llanos-Lagos et al. (2024), pooling 31 studies and 652 runners, found that high-load strength training and combined strength methods improved running economy across a range of speeds, while plyometrics helped economy at slower speeds. Uphill running supplies a similar resistance-like, force-producing stimulus within the running action itself. This does not make hills a full substitute for the gym, but it helps explain the economy improvements seen in the interval trials.

How steep and how hard should the hills be?

Two variables matter: intensity and gradient. On intensity, Barnes et al. (2013) found that although any high-intensity uphill interval work improved 5-km performance, the highest-intensity intervals were clearly optimal for running economy. That argues for genuinely hard efforts rather than moderate uphill jogging when economy is the goal.

On gradient, Alemu et al. (2025) compared three uphill slopes in middle-distance runners. The steepest gradient tested (~7.6%) produced the greatest improvements in maximal velocity and 800 m performance, while the intermediate gradient (~5.1%) also improved 800 m time. Taken together, steeper and harder appears better within the ranges these studies used. The honest caveat is that neither trial tested very steep gradients or long hill repeats, and the optimal dose almost certainly depends on the runner's event, training age and injury history. Progress gradually rather than jumping straight to maximal efforts on steep terrain.

Is uphill treadmill training as good as flat intervals?

For running economy, the evidence suggests it is comparable rather than clearly superior. Ferley et al. (2014) randomised 32 well-trained distance runners to six weeks of incline (uphill) high-intensity interval treadmill training or level-grade training. Both groups improved components of running economy, including submaximal oxygen uptake and the percentage of VO2max at lactate threshold, and the uphill work matched level-grade training on these measures.

One important limitation emerged: the uphill training was not a sufficient resistance stimulus to enhance isokinetic muscle power. In other words, incline intervals behaved like quality interval training rather than like strength training. The practical reading is that uphill treadmill intervals are a legitimate, joint-friendly way to run hard interval sessions and improve economy, but they should not be expected to replace dedicated strength or power work. Runners chasing power adaptations still need heavier or more explosive loading, as the strength-training literature indicates.

Can hill sprints make you a springier, more economical runner?

Short, maximal hill sprints are mechanically similar to intermittent sprint training, and the evidence there is promising but not conclusive. Thibault et al. (2025) had 25 highly trained runners complete 12 weeks of intermittent maximal sprint training. Leg stiffness increased significantly (+12.6%) and vertical displacement fell (-17.7%), both changes associated with more efficient, less bouncy running mechanics.

Running economy improved in 68% of participants on average, but the group-level change was not statistically significant. That is an important caveat: the mechanical adaptations were clear and consistent, while the economy benefit was individual and did not reach significance across the group. For runners, this supports including brief maximal hill sprints to develop leg stiffness and neuromuscular qualities, with the expectation that economy gains may vary from person to person. Because the efforts are short and uphill, impact loading stays relatively low, which suits their use as a supplement to easy runs.

Does downhill running improve running economy?

This is where a popular claim does not hold up well. It is sometimes argued that fast downhill running, by overspeeding the legs, sharpens economy. Shaw et al. (2018) tested this directly in a randomised controlled trial and found that a short supplementary programme of downhill run training did not enhance running economy in already well-trained runners. The energy cost of flat running was unchanged after both downhill and flat training.

That result tempers the idea that downhill running is a shortcut to better economy, at least for trained athletes over a short intervention. It does not mean downhill running is useless, but its value lies elsewhere, principally in preparing the muscles for the eccentric demands of hilly and downhill racing. As with all these trials, the intervention was short and the runners already trained, so we cannot rule out different outcomes over longer periods or in less-trained runners.

Is downhill running worth the muscle damage?

Downhill running carries a distinct cost. Bontemps et al. (2020), in a narrative review, explain that its eccentric muscle actions induce exercise-induced muscle damage, including altered muscle structure, temporary force loss and soreness that can last several days. Vernillo et al. (2017) similarly note that downhill running relies on eccentric contractions with greater impact loading and elevated injury and fatigue risk compared with uphill running.

The redeeming feature is the repeated-bout effect. Bontemps et al. (2020) describe how prior exposure to downhill running confers protection, reducing damage and strength loss on subsequent bouts. This means downhill work can be programmed progressively to build eccentric resilience for hilly and trail racing, rather than avoided entirely. The practical implication is to introduce downhill efforts gradually, well before a hilly race, and to respect the multi-day recovery window. Treat downhill running as specific race preparation and durability work, not as a routine economy session.

What does this mean for your training?

The evidence supports a clear hierarchy. Uphill intervals have the strongest, most direct support: Barnes et al. (2013) and Alemu et al. (2025) show economy and performance gains, favouring higher intensities and steeper gradients within the ranges tested. Ferley et al. (2014) confirms uphill intervals match flat intervals for economy, making them a joint-friendly option, though not a replacement for power training. Short maximal hill sprints, echoing Thibault et al. (2025), can build leg stiffness, with individual-level economy benefits.

Downhill running is different. Shaw et al. (2018) found no economy benefit in trained runners, so its role, per Bontemps et al. (2020) and Vernillo et al. (2017), is building eccentric resilience for hilly racing, introduced gradually to exploit the repeated-bout effect. Across all of this, the honest caveat is that the trials are small, short and often in already-trained runners, so treat specific percentages as guidance rather than precise prescriptions.

Do hills improve running economy?

Yes, chiefly uphill intervals. Barnes et al. (2013) found six weeks of uphill interval training improved 5-km running economy in well-trained runners, with the highest-intensity intervals optimal. Ferley et al. (2014) showed incline intervals improved economy comparably to flat intervals. Downhill running is the exception: Shaw et al. (2018) found it did not enhance economy in trained runners.

How steep should hills be for training?

Steeper gradients performed best in the available research. Alemu et al. (2025) compared uphill slopes and found the steepest tested (~7.6%) produced the greatest improvements in maximal velocity and 800 m performance, with an intermediate gradient (~5.1%) also helping. However, these trials tested specific ranges, so treat the figures as guidance and progress gradually rather than jumping to maximal efforts on steep terrain.

Are hill sprints worth doing?

They appear worthwhile for neuromuscular qualities. Thibault et al. (2025) found 12 weeks of intermittent maximal sprint training, mechanically similar to hill sprints, significantly increased leg stiffness (+12.6%) and reduced vertical displacement (-17.7%). Running economy improved in 68% of participants but the group-level change was not statistically significant, so the economy benefit varies between individuals.

Does downhill running make you faster?

Not by improving economy, according to the evidence. Shaw et al. (2018) found downhill run training did not enhance running economy in already well-trained runners. Its main value, per Bontemps et al. (2020), is building eccentric muscle resilience for hilly and downhill racing. Introduce it progressively to exploit the protective repeated-bout effect and manage soreness.

Why does downhill running cause so much soreness?

Because it relies on eccentric muscle actions. Bontemps et al. (2020) explain that downhill running induces exercise-induced muscle damage, including altered muscle structure, force loss and soreness lasting several days. Vernillo et al. (2017) add that it involves greater impact loading and injury risk than uphill running. Prior downhill exposure provides a protective repeated-bout effect that reduces subsequent damage.

Can uphill intervals replace strength training?

Only partly. Ferley et al. (2014) found uphill intervals improved running economy but were not a sufficient resistance stimulus to enhance muscle power. Llanos-Lagos et al. (2024) showed high-load and combined strength training improve economy across speeds. Uphill running supplies a useful force stimulus within the running action, but dedicated strength and power work remains distinct.