The Science And Theory About Training For Steep Trails

Published July 27, 2021 09:07AM

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Mount Marathon is one of the most brutal races in the world. In 3.1 miles, the race gains AND loses 3000 feet. It’s mountain racing at its purest. See that behemoth in your backyard? The winner is whoever is the first to touch the summit and get back to town. Hold onto your butts.

Every year in the race results, there’s something curious. Even if you’re a devout follower of trail running, there are some names you don’t hear often. Mixed in with trail running superstars like Hannah Lafleur (2-time defending champion, Sean O’Brien 50k winner) and Darren Thomas (3rd this year, Way Too Cool 50k winner) are bunches of…skiers. Nordic ski, so maybe the toughest activity in the world, but still…isn’t that a whole different sport?

A 2021 study in Frontiers of Physiology underscores a related point: maybe the different sport is not skiing. Maybe the sport that is different from regular running is very steep uphill and downhill running. What does that mean for long-term training? That question brings in some of the most debated topics in trail running training theory, including what I call “the climbing paradox.” Let’s dig in!

Study Overview

The study had 10 women and 19 men run at 4 different speeds (8 to 14 km/h) on 8 different grades (-20% to +20% in 5% increments), leaving out a few impractical testing conditions (i.e. the slowest speed at the steepest downhill grade), randomizing the order. For the 25 total conditions tested for each participant, the authors calculated and compared the net oxygen and metabolic costs of running. The big question: how does gradient affect running energy costs?

The main finding: level ground energy costs correlated with uphill energy costs except at the steepest grades (here, 20%). The study authors concluded that “compared to level and shallow slopes, on steep slopes ~±20%, running energetics are determined by different factors (i.e., reduced bouncing mechanism, greater muscle strength for negative slopes, and cardiopulmonary fitness for positive slopes).” That quote is lifted from the abstract, so you know I at least read past the title. Some people call me a hero; I say I’m just doing my job.

That conclusion overlaps with past studies. For example, a 2018 study in the European Journal of Applied Physiology found a strong correlation between running economy at 0%, -5%, and +7.5% grades. A 2016 study in the International Journal of Sports Physiology and Performance found correlation between the oxygen cost of running at 0% and +12% in elite trail runners.

But where is the overlap between those findings and the agreement that steep uphill and downhill running involve different biomechanics than level running (2017 Sports Medicine review article) and that hiking is more efficient at steeper grades for many athletes (2016 study in the Journal of Applied Physiology)? While we’re at it, let’s add another turd to the punch bowl for some smoky flavor. A 2016 study in the Journal of Sports Science & Medicine found no significant association in the energy cost of running between 0% and +12.5% in mountain runners. It seems like running fitness is running fitness, but as the grades get steeper, the correlations get weaker until we might be talking about a slightly different sport entirely.

The 2021 study was an important step in knowledge because it reinforced the idea that there is likely some inflection point over 10% but less than 20% where the biomechanics of running shift enough to reward different training. Where exactly that shift lies probably depends on the testing protocol, output variables, and individual variability, along with the race distance/intensity.

That’s probably what we are seeing at Mount Marathon, which is almost never below 30% grade for the middle portion of the race, so likely smooths away any inter-study variation. The 2017 review laid it out: “uphill running requir[es]] higher step frequency, more mechanical work, more power output at the joints, and greater muscular activity,” while downhill running involves higher rates of eccentric contractions and force absorption. Level and moderate-grade running can give an athlete general preparation for steep uphill and downhill running/hiking, but it must be coupled with some specific training for fitness to fully shine.

There is a complication, though. And I think this question is at the center of how training methods for trail running can seem to vary more than track or road running.

How much better can an athlete actually get with an overriding focus on steep training?

Now, let’s venture away from the study findings and into the world of training theory. This is all hotly debated, so view this as my opinion, rather than settled fact. The only thing I am sure of in life is that a hot dog is a sandwich. Everything else is open to interpretation.

At very steep uphill grades, athletes can excel being really strong aerobically and muscularly, even if they have not maximized their running speed potential (like skiers). Mount Marathon shares some similarities with Mount Sanitas in Boulder, where some of the fastest times are still held by elite cyclists. When the biomechanical demands involve more mechanical work and greater muscular activity on steeps, power and aerobic capacity (combined with specific practice) become the overriding limiters. The general ability of the aerobic and musculoskeletal systems can drive world-class performances, particularly in talented athletes.

That’s possibly backed up by a 2020 study in the European Journal of Sports Science that suggested knee extensor strength loss caused reduced climbing speed in ultramarathons. Who has really strong knee extensors? Skiers, cyclists, and mountaineers are certainly up there in the rankings, along with this guy who crushes a watermelon between his thighs.

Meanwhile, at level and moderate grades, there are two unique considerations. First, the neuromuscular and musculoskeletal adaptations to the specific demands of running become more significant. Second, the biomechanics of faster running become more important, as efficiency of motion becomes a big contributor to speed. Thus, the limiter shifts from raw muscular/aerobic strength and endurance on the steeps to a more nuanced mix of the neuromuscular, biomechanical, aerobic, and musculoskeletal systems on moderate and level grades.

To put it another way: very steep uphills can often be a competition to see who has the highest VO2 max/muscular strength combo. My contention (and a driving force behind the coaching approach we use at SWAP) is that moderate grades involve more variables with potentially more room for progress from a genetic baseline, so it’s a better long-term training focus.

The Climbing Paradox

I have seen many athletes progress their overall running economy long-term with an emphasis on well-rounded running training (see this 2006 case study on Paula Radcliffe, along with anecdotes from most top runners who peaked later in their careers). The history of short distance mountain racing includes many runners coming from the track or roads to excel on steep climbs, like Grayson Murphy, a track superstar and 2019 World Mountain Running Champion. That history shows that very fast athletes focusing on overall running economy can likely do specific training and quickly become strong on the steeps.

The 2018 European Journal of Applied Physiology study that found correlation between level, uphill, and downhill running economy is fascinating on this point. The authors theorized that the strong correlations were due to study participants having roughly equal practice/exposure to the different terrain types. It’s possible that many study participants are not running up 15%+ steep grades often in training (unlike moderate grades), so that biomechanical practice is likely lacking. Give a fast athlete some practice, and their ceiling of potential can be very high on most trails.

But does it work in the other direction? Can an athlete improve their running economy on the steeps long-term by focusing more exclusively on steep running?

The jury is out on that question, since the studies focus on snapshots rather than long-term trajectories. But my guess is no in most cases (unless the athlete is a talented genetic outlier). I call it the “climbing paradox”–focus excessively on steep ups and downs at the expense of well-rounded training, and eventually an athlete may get a bit slower at everything. The main rationale is that output on very steep terrain is capped for most athletes by the sheer muscular demands. Even in the 2021 study, only 6 of the 29 participants could run at 20% at all. Those 6 had high VO2 maxes, and my guess is that even they would eventually run into a wall when their muscles just can’t adapt to put out more power, particularly with age when peak power output goes down. The athlete doing a well-rounded mix of aerobic, speed, and steep training wouldn’t run into those same limiters, and would have more room to adjust as limiters change (and with age).

Fast-forward five years, and the athlete focused on well-rounded training might still have an offset where they are more economical at shallower grades, even after specific training. But their overall running economy can improve so much that even with those reductions, they are still able to hold their own. I’ll take 90% of a really, really big number over 100% of a smaller number any day, especially if we can keep improving that really big number over time.

To paraphrase Justin Timberlake’s character in The Social Network, “You know what’s better than a million disclaimers? A billion disclaimers.” That entire discussion is uncertain and needs more studies, with the uncertainty playing out on the front lines of mountain races across the world. Whether you agree or disagree with the analysis, the 2021 study highlights the need to do some specific training for steep trails. Here’s how I interpret those takeaways for athletes ranging from beginners to pros.

One: Develop running economy and the aerobic system year-round, with specific training blocks for vert

Running is running, until it becomes something more like power hiking or controlled falling. Even when hiking or falling, improving running economy will raise the ceiling on performance potential that can be achieved with specific training later. My general rule for steep races is that 6-8 weeks is usually enough to focus on the specific demands of vert-heavy events. Most of the year, well rounded training can involve a focus on speed, weekly workouts, and fun trails a few days a week. During specific training, try to do steep trails like the event 2-3 times per week at least, particularly on long runs (adding treadhills or downhill repeats if needed to achieve that specificity where you live). Short bouts at steep grades likely help too, since much of the economy offset may be owed to a complete lack of exposure to extreme grades in study participants. But even during specific vert-heavy training, maintain top-end speed via strides on hills and flats.

Note: These guidelines may be less relevant for an athlete purely focused on extremely steep, long ultras like the Hardrock 100, where most of the field is hiking most of the race.

Two: Hiking is an opportunity

In running (at least in short distances), most athletes will have a higher output than in hiking. The hard part is translating that output into an efficient hiking form given the unique biomechanical demands. All year, but especially during that 6-8 week specific training block, focus on purposeful hiking with good form. The treadmill is a great place to practice.

Three: Downhills require practice

The Mount Marathon skiers can be great downhill runners because they are skilled and fearless. All of us can work on developing our skills, even if we aren’t bombing down ski slopes. With form, think quick, light strides, letting the body relax and flow, viewing every downhill as an opportunity. In that specific phase, make sure you emphasize efficient, steep downhills so the eccentric contractions don’t rip up your quad muscles on race day (full training article here). I like athletes to do enough vert year-round to be somewhat adapted to the unique stress of those eccentric muscle contractions, with some evidence that it may help fatigue resistance in flat events as well.

Four: Strength work can prepare you for specific stress of steep trails

If you just run, you likely won’t be good at other things. And the 2021 study shows that very steep running borders on an “other” thing. Strength work is one way to bridge that gap, improving the concentric strength and eccentric resilience of muscles long-term without sacrificing well-rounded training. The 3-Minute Mountain Legs and/or 8-Minute Speed Legs are good options a few times a week. Step it up even more with this weekly strength cheat sheet. Or better yet, work with a strength coach. Your thighs will be crushing watermelons in no time.

Five: Cross-training can improve overall performance

No matter what we agree upon regarding running economy, aerobic development and muscular strength are big inputs at all grades. Since we can only run so much without getting injured, every run is inherently a trade-off. Steeps, or flats? Speed, or strength? Cross-training can be a training supplement that improves performance on all terrain, as long as it’s not adding excess fatigue. Biking is wonderful, as is ski, elliptical, hiking, and anything else you can think of that is not pool running. I am convinced that pool running is a practical joke that got out of hand.

Steeps are hard. But by focusing on long-term speed/aerobic development mixed with a non-excessive amount of specific steep training, you might realize something: you can be harder. I absolutely nailed that turn of phrase, no notes.