Staying safe running the trails: Understanding the dangers of downhill running
Author: By Doug James, intraining Physiotherapist, Podiatr
Running up hills is tough! It can feel like gravity has a personal vendetta against you.
Running uphill requires considerably more strength and effort compared to running at a similar pace on flat ground. The ‘however’ is the descent on the other side – a chance to catch your breath, regather your speed and let gravity make it to you for being man to you on the way up.
Training on hills can have enormous benefits to your fitness and running ability, with many road runners turning to the trails to bridge the offseason between races. Being a capable downhill runner can make a significant difference to your running performance in a race and reduce your risk of injury while training.
While road runners tend to seek out flatter terrain (hence the popularity of the Gold Coast Marathon), hills are part and parcel of most trail runs. In order to get the most out of your trail running, or a hilly road race, it helps to understand what goes on – and what can go wrong when running on hilly terrain.
Impact on running form
There are a few key differences in the way that you run on hills compared to flat ground. When running uphill, your stride length decreases, step rate increases, and work rate (effort) increases proportionally with the steepness on the terrain . In contrast, downhill run is typically linked to longer stride length, lower step rate per minute, and decreased effort – between 0-20% negative gradients (work rate actually increases on very steep downhill sections) [1,3].
Downhill running also alters the way your legs respond to impact, and this will vary based on your level of experience, conditioning and if you are currently injured. Interestingly, ground contact time – a factor linked to numerous overuse running injuries – tends to be higher on trails than road, irrespective of the terrain. Knee movement is also quite different with downhill running compared to flat terrain running. Landing tends to occur on straighter legs, but there is far more flexion (bending) during the shock absorption phase which may explain some muscle and joint soreness felt after a run.
Running form can be harder to maintain during downhill running. Your ability to keep your hips level, and knees stable is more difficult due to the increased impact forces and rapid foot strike rate. Additionally, fatigue and your attention level are likely to be affected due to the challenging terrain which will further diminish running form quality.
While the downhill component is enjoyable, as discussed, it can be more taxing on the body and is not without some risk. These risks or dangers can be classed into different categories – traumatic injuries and overuse injuries.
Traumatic injuries include things such as ankle sprains and fractures.
Ankle sprains are more likely when running downhill compared to uphill due to the velocity and landing position of your foot. If you get out of control or fail to negotiate an obstacle you can be left with a very uncomfortable injury to your ankle and a long walk back to the finish. Ankle sprains can have a frustratingly long recovery time.
Fractures can and do occur during running (possibly more likely on trails). Different from stress fractures which tend to be a result of overtraining, traumatic fractures can happen in an instant and may be caused by slipping over or falling off a trail.
Running in shoes with poor grip or on slippery surfaces, having poor visibility, or attempting terrain beyond your ability may result in a fall resulting in fracture. Ribs and arm bones are particularly prone to fracturing, so it pays to make sure you have the right shoes and equipment with you, and run within your limits. Rib fractures can be a medical emergency particularly if they are accompanied by difficulty in breathing and should be assessed in an Emergency Department at a hospital urgently.
Overuse injuries are common in distance runners –occurring to both those that run on the road and on trails. They occur when the level of exertion exceeds the ability of tissue (muscle, tendon, ligament and/or bone) to adapt. This can occur during a single run but is more likely to result after several runs where there hasn’t been sufficient recovery.
Overuse injuries are common in newer runners (those with less than one year of recent running history) but can occur to more seasoned runners that increase their running volume and/or intensity too much and too quickly.
Four common overuse injuries linked to downhill running are:
1. Pain under the knee cap – Patello-Femoral Pain syndrome (PFPS)
PFPS is pain around the knee cap (patella) caused by it rubbing on the thigh bone. With comfortable paced walking and flat ground running the patella should glide smoothly as the knee bends and straightens. Downhill running results in increased movement and pressure on the knee making this injury more likely.
Similar to PFPS, the increased bending of the knee will increase strain on the tendons around the knees. Soreness above and/or below the knee cap may be a sign that the tendons have become injured.
ITBS is a particularly nasty running injury frequently seen as a result of downhill running – either too much of it or with poor technique.
This is an injury that can affect road and trail runners, particularly those that increase their training load too rapidly. Aside from load management issues, MTSS may be more likely in downhill runners due to increased impact, tibia torsion (twisting of the shin), or muscular vibration as the calf and ankle flexor muscles work to absorb shock and stabilise the leg.
Beyond healing, rehabilitation of the above injuries involves understanding the mechanism of why they happened and how to reduce the risk of reoccurrence. Improving your downhill running technique can help to reduce these injury risks.
Becoming good at downhill running can be hugely rewarding, and while it’s not without risks, being aware of what can go wrong can help to minimise the dangers.
Tip: Find it tricky to make time to do your exercises?
Get Doug’s #1 exercise he recommends staying strong running downhill. Click HERE.
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Other useful tips:
3 key strength exercises taken from our “Trail Running Exercise Plan”. These are a great snapshot you can use to start your trail running strength program.
(1) Björklund, G., Swarén, M., Born, D., Stöggl, T. (2019) Biomechanical Adaptations and Performance Indicators in Short Trail Running. Frontiers in Physiology. 10, 506. URL=https://www.frontiersin.org/article/10.3389/fphys.2019.00506
(2) Franz, J. R., Lyddon, N. E., & Kram, R. (2012). Mechanical work performed by the individual legs during uphill and downhill walking. Journal of Biomechanics, 45(2), 257–262. https://doi.org/10.1016/j.jbiomech.2011.10.034
(3) Vernillo, G., Giandolini, M., Edwards, W. B., Morin, J.-B., Samozino, P., Horvais, N., & Millet, G. Y. (2017). Biomechanics and Physiology of Uphill and Downhill Running. Sports Medicine (Auckland, N.Z.), 47(4), 615–629. https://doi.org/10.1007/s40279-016-0605-y