Trail running often involves more undulating terrain than road running; and when you move into the world of mountain races and sky running, then there is always significant elevation change. Often this can involve technical descending, where good technique and mental focus are required for a successful race.
But how do you train to prepare for going downhill fast on this type of terrain?
Recent research by Björklund et al., (2019) discovered that, when trail runners were running downhill, they experienced peak force (hitting the ground harder) than on level or uphill sections of trail. This confirms other research, such as that by Gottschall and Kram (2005). The latter discovered that on a -9 degree slope impact force (compared to flat running) increased by 54 percent and breaking force increased by 73 percent.
Björklund et al., (2019) also found that the performance between runners varied most when descending, and of the three downhills studied, the largest variance in time was on the most technical section. Therefore, if a descent, is technical it will lead to greater time differences relative to a more runnable descent.
When it comes to longer races, such as mountain ultramarathons, research has revealed that runners’ average speed decreases throughout the race. However, when analyzing level, uphill and downhill running over the course of a race, the decrease in speed was greatest in the downhill and level running sections. Furthermore, speed continued to drop up until the last section of the race for downhill running, which was not the case for flat or uphill running, where the reduction in speed plateaued (Kerherve et al., 2016)
If you can maintain your downhill running speed in longer races, and improve technical descending, there are opportunities to improve race times.
How often should you practice downhill running?
Unfortunately, it may not be as simple as going out and doing downhill repeats as you may do for uphill running.
It has been shown, linked with the increase in force as mentioned above, that “downhill running substantially increases the probability of overuse running injury” (Gottschall and Kram, 2005). Relative to running on the flats, downhill running typically sees a reduction in cadence (steps per minute) and a greater time in the air (Vernillo et al., 2017). This may go some way to explaining why the force is greater on landing.
This increase in landing force has an impact on your legs. Chen et al. (2007) showed that athletes that ran for 30 minutes on a -15 percent slope had a decrease in running economy of between four to seven percent for several days after the downhill session. Furthermore, perceived muscle soreness peaked two days afterward.
If you adopt downhill run training as part of your weekly workouts, it can impact sessions later in the week leading to less training overall. But that isn’t to say that downhill running is all bad and should be avoided. In fact, downhill run training has been shown to improve knee extension strength, and the ability to change direction (Toyomura et al., 2017), which may be useful for technical trail runs.
Adopting a measured approach is best to improve my descending skills and speed.
Key Elements of Downhill Running Technique
Typically when descending stride length increases, cadence drops and time in air increases. This is partly due to changes in running form and leaning back more, and applying a braking force with a heel strike.
When descending, try to increase your cadence by taking shorter steps and landing more on the mid to forefoot. This is essential on more technical terrain. Additionally, shift your body forward to stay perpendicular to the hill; this will help bring your center of gravity forward and help you land with your weight over your feet.
Another good goal is to try to run quietly. If your feet are hitting the ground with a larger force, they are likely to make more noise. A simple way to try and improve your form is by descending quietly, with light steps.
Consider Elevation Gain
When training for a particular race, look at the total amount of climbing relative to the distance and try to simulate this in training. For example, if you are doing a mountain marathon with 8,000ft of descending, and you have a 10-mile training run planned, aim to descend between 3,000 and 3,100ft (8,000ft / 26 miles = 308ft per mile.).
This will get your legs used to the elevation change ahead of the race without overloading them.
Technical Descending Practice
After a good warm-up, find a short hill, ideally with similar terrain to the race you are doing. Starting at the top, descend for 20 seconds working on technique and form, as per the first point above. This is not about hammering down, but being smooth and efficient.
Walk back to the top (this is your recovery), and then descend for 40 seconds. Continue like this for 60, 80, 100, 120 seconds and then cool down.
By repeating the same section of trail multiple times you will hopefully improve your technique and ability to pick the best line, as you become more familiar and confident on the terrain.
I would only do this once every two weeks to give your body time to recover. The next time you can start near the bottom, and then walk higher up the hill each time (so the end of the interval is most familiar). If you struggle with confidence when descending, wearing some mountain biking gloves may help as you know your hands will be protected if you fall.
Björklund, G., Swarén, M., Born, D.P. and Stöggl, T.L., 2019. Biomechanical adaptations and performance indicators in short trail running. Frontiers in physiology, 10, p.506.
Breiner, T.J., Ortiz, A.L.R. and Kram, R., 2019. Level, uphill and downhill running economy values are strongly inter-correlated. European journal of applied physiology, 119(1), pp.257-264.
Chen, T.C., Nosaka, K. and Tu, J.H., 2007. Changes in running economy following downhill running. Journal of sports sciences, 25(1), pp.55-63.
Gottschall, J.S. and Kram, R., 2005. Ground reaction forces during downhill and uphill running. Journal of biomechanics, 38(3), pp.445-452.
Kerhervé, H.A., Cole-Hunter, T., Wiegand, A.N. and Solomon, C., 2016. Pacing during an ultramarathon running event in hilly terrain. PeerJ, 4, p.e2591.
Toyomura, J., Mori, H., Tayashiki, K., Yamamoto, M., Kanehisa, H. and Maeo, S., 2017. Efficacy of downhill running training for improving muscular and aerobic performances. Applied Physiology, Nutrition, and Metabolism, 43(4), pp.403-410.
Vernillo, G., Giandolini, M., Edwards, W.B., Morin, J.B., Samozino, P., Horvais, N. and Millet, G.Y., 2017. Biomechanics and physiology of uphill and downhill running. Sports Medicine, 47(4), pp.615-629.