Short answer: Road running and trail running have drifted into two different cultures. Road is built around control, speed, and objective results. Trail is built around community, unpredictability, and the experience of the race itself. Each can borrow from the other: road runners gain patience, joy, and a healthier relationship with outcomes from trail, while trail runners can borrow road's structure, professionalism, and rigor. The risk, according to Olympic medalist Molly Seidel, is that trail loses what makes it special if it chases road's win-at-all-costs playbook too hard.
Molly Seidel is one of the very few runners who can speak to both worlds from the top. She took marathon bronze at the Tokyo Olympics, then spent the last year moving all in on trail and ultra, finishing her 100-mile debut at Western States. On For The Long Run, she talked through what the two sports actually teach each other. Here is the breakdown.
What road running can learn from trail
The single biggest thing road can take from trail is that the result is not the only reason to race.
Molly came up through competitive high school track, college, and pro road marathoning, where the entire purpose is to compete and win. Trail cracked that open for her. Over the back half of a hundred-mile race, when a fast time was long gone, she discovered value in racing that had nothing to do with place: the people on the course, the crews, the meaning of finishing something legendary. Road running, by contrast, tends to treat anything short of a personal best as a failure.
The second thing is community. Molly described being overwhelmed by how positive trail running is. Even on her worst day, walking, missing every goal she'd set, every runner and crew member she passed was thrilled she was still out there. As she put it, that kind of reception "never would happen in road racing." Road culture could stand to celebrate the finisher, not just the winner.
The takeaway for road runners: hold your goals more loosely. Chasing a time is good and the objective stepping stones matter, but the accomplishment itself is rarely what brings the joy. The person you become chasing it is the actual prize.
What trail running can learn from road
Trail's strengths are also its blind spots. The looseness that makes it joyful can shade into a lack of structure, and this is where road has something to teach.
Road running is relentlessly professional. It has decades of accumulated knowledge about periodization, pacing discipline, fueling precision, and building a season around peak races. Molly's own path shows the value of that rigor traveling uphill into trail: she used road-style threshold work to prepare for ultras, and her marathon speed is a weapon on runnable trail courses that pure trail runners can't match.
Trail runners chasing performance can borrow road's habits of measurement and preparation without adopting its culture wholesale. Structure and joy are not opposites.
What should trail running guard against as it grows?
This is the question Molly actually cares about, and it is the more urgent one. Her worry is not that trail can't learn from road. It's that trail will copy the wrong things.
She was blunt that road, in her view, has already chosen its path: carbon plates, ultimate speed, winning at all costs, with the athletes' stories treated as an afterthought. Her fear is trail becoming a pure numbers game the same way. She'd ban carbon plates in trail racing outright, right now, before the arms race takes hold.
Her cautionary tale is professional cycling, where optimization has, in her words, turned the athletes into "computers with legs" and calculated the joy out of the sport one watt at a time. Growth is good, she said, but growth for its own sake can be as destructive as monetization for its own sake. The thing worth defending is the intangible part of trail: the joy, the self-discovery, the piece you cannot put a number on.
Does training for trail make you a better road runner?
Molly believes it does, and is honest that it hasn't been proven yet. There isn't a clear example of someone making that round trip and coming back faster on the road, so for now it's a bet.
There is a concrete mechanism, though, and it's about perspective. When your normal long run is four to six hours, a two-hour road long run stops being intimidating. The distances that used to scare you become routine. A runner who has been on their feet for twenty-four hours can draw on that forever. Molly talked about a thirty-mile long run now feeling normal, where a twenty-four miler used to rattle her. That mental reframe, that recalibration of what counts as "long" or "hard," is real fitness that follows you back to the road.
Her larger goal is to become a healthier, more complete athlete by building on training she genuinely loves, rather than only throwing herself at the wall the way marathon buildups demand.
How road and trail actually train differently
A few practical contrasts came out of the conversation that are worth knowing if you're thinking about crossing over.
Control versus letting go. Road running lets you control almost everything: your pace, your splits, your effort. Trail forces you to release that. You have to trust the terrain, other people, and yourself, and accept that a ten-minute mile might be harder than a five-minute one depending on the climb.
Fueling. On the road, gels make sense because they're the fastest way to take in calories at speed. On trail, you can and should eat real food, including the chewy candy road runners avoid. Molly is partial to honey mustard Dots pretzels, which she'd never touch mid-marathon.
Skill as a limiter. Road fitness doesn't transfer cleanly to technical descending. An elite engine is not enough on steep, rocky downhills, which is a skill you have to build over time. This is exactly what humbled Molly early, and it's why an Olympian can't simply walk in and dominate a trail race.
The bottom line
Road and trail running are increasingly two different sports that happen to share a verb. The healthiest version of each borrows from the other: road can learn joy, community, and a looser grip on outcomes; trail can learn structure and rigor. The warning underneath it all is that the borrowing has to be deliberate. If trail imports road's optimize-everything culture without thinking, it risks losing the exact things that are drawing so many road runners to it in the first place.
Want the full conversation? Listen to Molly Seidel on For The Long Run.