Downhill Running: How To Protect Against Muscle Damage

Written by:

Cliff Pittman

CTS Pro Ultrarunning Coach

Updated On

September 2, 2026

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Downhill Running: How To Protect Against Muscle Damage

Downhill running can be very hard on your legs, to the point that muscle damage from downhill running frequently leads to DNFs in ultramarathons. CTS Ultrarunning Head Coach Jason Koop has written extensively about downhill running in his book, “Training Essentials for Ultrarunning” and in multiple articles on our website (see resources list at the bottom of this article). I’m going to take a slightly different approach by giving you what you need to know in a shorter, more concise format.

Why Downhill Running Damages Muscle

Running downhill causes muscle damage because of repeated, high-force, eccentric muscle contractions. When a muscle shortens as it produces force, it’s called a concentric contraction. When a muscle produces force as it is lengthening, it’s called an eccentric contraction.

The big muscle groups in your legs (quadriceps and hamstrings) experience eccentric contractions as you run downhill because they are working to decelerate your body mass to keep you in control and absorb ground reaction forces that are much higher than you experience running on flat ground or uphill.

Eccentric contractions generate more force per motor unit than concentric contractions, and they do it while the muscle fibers are being stretched under load. That combination causes microtrauma at the cellular level.

Running downhill is not hard on your cardiovascular system, but it’s hard on muscle tissue. As you go faster – or try to – ground reaction forces increase, the eccentric contractions to decelerate your body mass become more powerful, and you incur more muscle damage more quickly. This is why hammering downhill without the proper preparation is a very unwise choice.

Best Practices for Minimizing Muscle Damage From Downhill Running

The good news is that you can improve your capacity to meet the demands of downhill running, reduce muscle damage, and keep your legs going for the climbs and descents still to come. The even-better news is that inoculating yourself against the most harmful effects of downhill running requires much less work than you might think. Here’s what you need to know:

• How much downhill training is needed? Not much. One targeted downhill session every 2-3 weeks is enough to initiate and maintain positive adaptations. You will be sore after the first one or two and need 2-3 days of rest and recovery. Subsequent sessions will induce far less soreness and require less recovery time.
• Would more frequent downhill training help even more? There’s a benefit to maintaining downhill running adaptations by incorporating training sessions every 2-3 weeks. Research does not indicate that increasing this frequency to weekly or semi-weekly yields additional benefit.
• How fast/hard should I run downhill in training? No faster/harder than Zone 3. Think of downhill running as a skills exercise rather than a fitness/cardiovascular exercise. The intensity is not the important part. The faster you run downhill, the more muscle damage you cause, which lengthens your required recovery time, which reduces the amount of meaningful aerobic training you can accomplish in a given training block or period. Going faster also increases the risk of falls and injuries dramatically.
• So, how do I get faster at running downhill? Improve your skills. We have an article on how we teach downhill skills at CTS Ultrarunning Camps. The short version is that you need to develop your “trail vision” to pick an efficient path through technical terrain and learn to “run quietly” by absorbing the impact rather than clomping down the trail. As your skills improve, you move more confidently and efficiently, which almost always means moving faster with minimal extra work.
• How steep should my downhill training sessions be? Ideally, individual sessions should match the average or typical rate of descent (feet/mile or meters/kilometer) of your goal event. If that’s not possible, downhill sessions outdoors on available trails are still preferable to downhill treadmill running because of the skills component. If you live in a flat area, then downhill treadmill running or the downhill ramps in parking garages can work.
• Can strength training replace downhill run training? Not entirely. Eccentric strength training exercises, like the exercises described in this article, can be an important component of preparing your muscles for the stress of downhill running. However, the joint angles are different, the neuromuscular coordination is different, and the skill components (foot placement and pattern recognition on variable terrain) simply don’t develop in a squat rack. A slow, eccentric step-down from a bench to the smooth floor is controlled and predictable. A technical descent at race pace is not.

Advice for Mountainous Ultramarathons

You can’t make mountains out of mole hills, and it’s hard to use mole hills to prepare for mountains. Conditioning your legs for eccentric contractions is useful for all trail runners, but athletes preparing for mountainous ultras should consider taking this preparation another step further. If you are preparing for Western States, Ultra Trail du Mont Blanc, a Grand Canyon Rim-to-Rim run, or anything that features substantial descents, I recommend a training camp either on course or in terrain that most closely resembles the course.

A training camp a few weeks before a mountain race works very well for athletes coming from flat ground. Even a few days of experiencing race-specific terrain creates a benefit that’s hard to manufacture anywhere else. The first day or two of that camp will cause soreness, mostly because of the repeated exposure on back-to-back days. Remember not to overdo it, either with hours or pace. Once you’re through the initial exposure, the repeated bout effect kicks in and your legs will handle subsequent descents with meaningfully less damage.

The Even Shorter Summary

Downhill running destroys legs because of repeated high-force eccentric contractions that cause cellular damage, even though the effort feels easy because of the low cardiovascular demands. Fortunately, muscle tissue adapts quickly to repeated bouts of eccentric training, and most of the adaptations happen after just a handful of moderate-intensity downhill runs. After that, maintenance exposures every 2-3 weeks are enough to retain the adaptation without disrupting the rest of your aerobic training.

• More isn’t better.
• Harder and faster downhill training sessions just increase injury risk and recovery needs.
• Downhill running is a test of skill more than a test of fitness
• Strength training can support tissue adaptations but not replace downhill-specific work.
• In order of preference, run downhill outside on trails > run downhill outside on smooth surfaces > run downhill on a treadmill.

Resources:

• Try These Eccentric Strength Training Exercises for Improved Downhill Running Performance
• How to Run Downhill Faster in Ultramarathons
• Downhill Running: How to go faster and hurt less
• Tips for Better Downhill Running in Ultramarathons
• Khassetarash, A., Vernillo, G., Krüger, R. L., Edwards, W. B., & Millet, G. Y. (2022). Neuromuscular, biomechanical, and energetic adjustments following repeated bouts of downhill running. Journal of sport and health science, 11(3), 319–329.
• Millet, Guillaume Y., Katja Tomazin, Samuel Verges, Christopher Vincent, Régis Bonnefoy, Renée-Claude Boisson, Laurent Gergelé, Léonard Féasson, and Vincent Martin. 2011. “Neuromuscular Consequences of an Extreme Mountain Ultra-marathon.” PLOS ONE 6 (2): E17059.