Are Hills Hurting You—or Are You Just Not Ready for Them?

Living and running in Atlanta, avoiding hills is almost impossible.

I frequently have runners tell me that “Hills hurt.” Sometimes my clients have stopped running hills completely because they assume hills are bad for their knees, Achilles, calves, hamstrings—or whatever happens to be bothering them.

But hills aren't inherently bad. They are just a different training stimulus.

Just like adding mileage or speed work, adding hills changes what we are asking the body to do. If we introduce that demand too quickly, or the runner isn't prepared for it, symptoms can show up.

Uphill and Downhill Are Two Different Things

We tend to lump “hill running” into one category, but running uphill and running downhill create very different demands.

Uphill running generally decreases impact forces compared with level and downhill running, even though it can substantially increase the metabolic demand.¹˒²

In other words, your heart and lungs may be working harder while impact forces are actually lower.

Downhill running is different. As the grade declines, impact and braking forces increase, and your muscles have to do more eccentric work to control your body as you move downhill.¹˒²

This helps explain why you can feel great cruising downhill and wake up the next morning wondering what happened to your quads.

Downhill Running Changes Where the Work Goes

The differences aren't limited to impact.

Research comparing uphill, level and downhill running has found that the relative contribution of the lower-extremity joints changes with slope. During downhill running, the relative contribution from the knee increases while contributions from the hip and ankle decrease.³

I find this really useful clinically.

If I'm working with a runner who has certain types of knee pain, I may be more cautious about how quickly we reintroduce significant downhill running. Research examining patellofemoral joint stress also shows that changing incline or decline changes the demands placed on the patellofemoral joint.⁴

This doesn't mean downhills are universally bad for your knees. It means downhill running creates a specific demand that your knees—and the rest of your body—need to be prepared to handle.

Building Tolerance for Hills

This is where I think runners sometimes get into trouble.

Imagine that you normally run relatively flat roads. Then you sign up for a trail race, start doing hill repeats twice a week or head to the mountains for a weekend of running.

You haven't simply added “a few hills.” You've changed the mechanical and physiological demands of your training.¹

Your body can adapt to those demands, but it needs time and repeated exposure to do it.

I think about hills the same way I think about mileage, speed work and long runs. Running 40 miles per week isn't inherently good or bad. I want to know what the runner was doing before they reached 40 miles, how quickly they got there and how their body responded along the way.

Elevation should be approached the same way. A runner who has spent months running flat roads isn't going to have the same tolerance for repeated climbing and descending as someone who regularly trains on hilly terrain.

Hills Can Be a Useful Training Tool

I don't want runners to be afraid of hills. I actually use them strategically.

I also sometimes use uphill running as part of a return-to-running program. Because running uphill can reduce some impact-related forces compared with level running,¹˒² it can be a useful way to manipulate load as we transition an athlete back to running. This can also be considered with postpartum runners; postpartum rehabilitation literature has suggested beginning running on a slight incline in some athletes and gradually reducing the incline as their ability to tolerate impact improves.⁶ This isn't appropriate for every runner or every injury, but it is another example of how hills can be used as a rehabilitation tool rather than something we automatically avoid.

Uphill running can provide a significant cardiovascular stimulus while changing the mechanical demands compared with level running.¹ Downhill running also creates adaptations when it is progressively introduced, and downhill training has been studied as a way to improve muscular and aerobic performance.⁵

When I'm working with a runner, I'm thinking about the person in front of me. What are they training for? What injury are they returning from? What terrain have they been running? How much elevation are we adding? How quickly are we adding it? Do they have the strength and capacity to tolerate those demands?

If we're returning from an injury, I may start with flatter running and gradually introduce elevation. Hills can become another variable we progress, just like mileage, duration and speed.

Should You Keep Running Hills?

In most cases, I don't want runners to become afraid of hills or eliminate them indefinitely. I want to figure out how much elevation they can currently tolerate and build from there.

If hills consistently reproduce your symptoms, look at how much elevation you're running, how quickly you introduced it and what else changed in your training at the same time. Depending on the injury, we may temporarily reduce the amount of climbing or descending, modify the grade, or introduce hills in smaller doses while building strength and running capacity.

And if you're training for a hilly race, hills eventually need to be part of your preparation. Avoiding them until race day leaves your body less prepared for the demands you're going to encounter.

You don't necessarily need to stop running hills. You may need to get better prepared to run them.

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References

1. Vernillo G, Giandolini M, Edwards WB, et al. Biomechanics and physiology of uphill and downhill running. Sports Med. 2017;47(4):615–629.

2. Gottschall JS, Kram R. Ground reaction forces during downhill and uphill running. J Biomech. 2005;38(3):445–452.

3. Shih Y, Ho CS. Lower-extremity support moment during uphill, level and downhill running. J Sports Sci Med. 2023;22:111–116.

4. Ho KY, French T, Klein B, Lee Y. Patellofemoral joint stress during incline and decline running. Phys Ther Sport. 2018;34:136–140.

5. Toyomura J, Mori H, Tayashiki K, Yamamoto M, Kanehisa H, Maeo S. Efficacy of downhill running training for improving muscular and aerobic performances. Appl Physiol Nutr Metab. 2018;43:403–410.

6. Selman R, Early K, Battles B, Seidenburg M, Wendel E, Westerlund S. Maximizing recovery in the postpartum period: a timeline for rehabilitation from pregnancy through return to sport. Int J Sports Phys Ther. 2022;17(6):1170–1183.