Trail running has grown significantly in recent years. That’s great. More people running on trails means more people getting closer to nature, discovering mountains, forests, parks, historic paths and landscapes that might never have been accessed through road running.
But that growth also brings a challenge.
Many runners arrive at trail running with excellent physical preparation, training discipline, a GPS watch, training plans, specific shoes and a focus on performance. But they don’t always arrive with an established outdoor culture. Many come from road running, where the environment is different, the rules are different and the environmental impact isn’t always so evident.
On an asphalt road, dropping a cup in a race zone is bad, but there’s usually a cleanup crew shortly after. On a trail, a gel packet, a torn wrapper, used toilet paper, a shortcut cut through vegetation or poorly removed trail markings can remain for a long time — and the impact multiplies when hundreds or thousands of people repeat the same behavior.
Data released by the UTMB World Series and Strava help put this growth into perspective: in the first half of 2025, participation in races with a UTMB Index was 2.4 times higher than in the same period in 2022, with more than 800,000 race starts in six months; 42% of those runners were participating in their first trail running race.
The problem, most of the time, is not bad faith. It’s a lack of knowledge. And that’s exactly where Leave No Trace comes in.
Leave No Trace is not a list of rigid rules. It’s a framework of principles to reduce the impact of our outdoor activities. These principles can be applied in different environments and modalities, from remote areas to urban parks, and serve as a simple foundation to guide more responsible choices.
In trail running, the principles are the same. What changes is how they are applied.
Illustrative image generated by artificial intelligence.
For Gabriela Corrêa, brand head at WTR, implementing minimum impact practices in trail running races is essential because the sport takes place precisely in natural environments, often in sensitive areas of great environmental value that are difficult to access.
“Every operational choice matters: what we include in the kit, how the hydration points work, how waste is sorted, how suppliers are briefed and even how the trail is prepared before and after the race. WTR already structures its actions with a focus on environmental education, waste management, trail conservation and local partnerships,” she explains.
Principle 1 — Plan ahead and prepare
In trail running, this means: planning goes beyond pace, elevation, hydration and race strategy.
Running on trails demands physical preparation, but also environmental and technical preparation. The athlete needs to know the course, understand the type of terrain, check the weather forecast, find out if there will be cell service, upload a reliable route, know how to use a GPS watch or navigation app, and let someone know their plan when training alone.
Illustrative image generated by artificial intelligence.
A trail run can take a person far from their car, home, a road or any point with cell service. In the event of a wrong turn, fall, sprain, hypothermia, dehydration or delay, what seemed like a simple training run can turn into a rescue situation.
And rescues also have an impact. They mobilize people, vehicles, teams, off-trail movement and pressure on natural areas. The priority will always be to save lives, but the best way to reduce that impact is to prevent foreseeable situations from happening.
Planning, therefore, is also an act of minimum impact.
For organizers, this principle begins before registration opens. A race needs an authorized course, risk assessment, emergency plan, clear communication with athletes, information about mandatory equipment, guidance on hydration, aid stations, waste disposal, restrooms and environmental conduct.
Principle 2 — Travel and camp on durable surfaces
In trail running, this means: run on the trail, stay on it and don’t create new trails.
This is one of the most important principles for runners, and where we observe a great deal of impact occurring.
In the context of trail running, “durable surfaces” are primarily existing trails, dirt roads, rock, gravel and other places capable of receiving foot traffic without amplifying impact. The practical rule is simple: if a consolidated trail exists, stay on it.
This means not cutting corners, not opening a second line to pass another runner, not going around mud by stepping on the vegetation beside the trail, not leaving the course to gain a few seconds and not turning a congested section into an excuse to forge a path where none exists.
Leave No Trace recommends that runners go through wet sections, puddles and obstacles rather than going around them, precisely to avoid creating new trails and damaging lateral vegetation. It also advises choosing a different route when a trail is excessively muddy and needs time to recover.
This can seem counterintuitive. The runner’s natural tendency is to avoid mud to keep their shoes dry, avoid slipping, maintain rhythm or keep their gear clean. But from a minimum impact standpoint, the right thing to do is often to accept the trail as it is.
When hundreds of runners detour around the same puddle or the same muddy section, the trail widens. Vegetation gets trampled, soil becomes exposed, water starts flowing along new paths and the erosion process accelerates. What was a small individual decision becomes a collective problem.
Illustrative image generated by artificial intelligence.
For organizers, this principle is even more sensitive. A race course must respect existing trails, sensitive areas, conservation unit regulations, local communities, buffer zones and the environment’s carrying capacity. Opening trails without authorization, routing through fragile areas or placing athletes in locations that shouldn’t receive that level of traffic is not just a technical error. It is a violation of the sport’s ethics.
A recent case in Brazil shows that this debate is not theoretical. In May 2025, the Rio de Janeiro State Environment Institute – Instituto Estadual do Ambiente do Rio de Janeiro (INEA) fined the Transmantiqueira Ultra Trail Agulhas Negras, known as TUTAN, held in Resende, for illegal deforestation and environmental crimes against the Atlantic Forest. The race allegedly took place without environmental authorization from INEA and involved the clandestine opening of trails, with approximately 615 meters deforested within the Parque Estadual da Pedra Selada and another 260 meters in the unit’s buffer zone. Among the damages cited were soil compaction, erosion, alteration of natural drainage, intervention in an area with slopes exceeding 45° and impact on the juçara palm (Euterpe edulis).
Cases like these must serve as a warning.
The runner is not responsible for all of an organization’s decisions. But by registering, sharing, starting, posting photos and celebrating a race, they help legitimize that event. That’s why choosing wisely where to run is also part of a minimum impact ethic.
Before registering, it’s worth asking: does the race have authorization from the area’s land managers? Does the course use existing trails? Does the organization explain its environmental practices? Is there a waste management plan? Will the signage be removed after the race? Are there restrooms at the start, finish and key points? Does the number of participants seem compatible with the location? Does the race contribute to trail maintenance, conservation units or local communities?
If a race causes environmental damage, opens unauthorized trails or ignores the rules of a conservation unit, the community’s response cannot simply be “but the course was beautiful.”
The athlete doesn’t only choose where to run. They choose what kind of trail running culture they want to help build.
Principle 3 — Dispose of waste properly
In trail running, this means: everything you take onto the trail needs to come back with you — including small trash, used toilet paper and feces.
When people talk about Leave No Trace in trail running, the first image that usually comes to mind is a gel packet tossed on the trail. And, indeed, that is a problem.
But the impact isn’t only in the obvious trash. It’s also in the torn corner of the packet, the seal, the tiny piece of an energy bar wrapper, the salt capsule, the napkin from the aid station, the candy wrapper and all the microtrash that can fall without the athlete even noticing.
Leave No Trace points out that many runners don’t litter on purpose, but that it’s easy to lose small bits of waste during a run. That’s why it recommends athletes have a plan before heading out: a dedicated pocket, a zip-close bag, a ziplock, a reusable flask or another secure system for storing wrappers and waste.
In trail running, this needs to be thought through realistically. The athlete might be tired, wearing gloves, running in the dark, cold, in the rain or trying to open a gel on a technical descent. Without a simple system, the chance of something falling increases.
I remember when I did El Cruce in 2022, the organization prohibited the use of gel packets, which meant runners had to transfer their gel into flasks before the race.
The rule is simple: if you carried it full, you can carry it back empty.
Human waste is also waste
This point needs to be addressed clearly: runners may also need to use the bathroom in the middle of a training run or a race.
It’s not a pleasant topic, but it is a necessary one. Anyone can feel the urge to defecate during a long race, an ultramarathon, a training run in a remote location or an event lasting many hours. That’s why runners need to have thought about what they’ll do beforehand.
The classic Leave No Trace guidance, when the location permits, is to bury feces in an adequate hole known as a cat hole, well away from trails, campsites and water sources. But that requires appropriate soil, sufficient distance, a digging tool, privacy, time and knowledge. In many trail running situations, especially during races, that simply isn’t realistic.
On heavily used trails, in sensitive areas, rocky terrain, conservation units, locations where digging is not permitted or races with large numbers of athletes, the most responsible approach is to pack everything out using a dedicated human waste system.
In trekking, solutions already exist for this, such as the Lixeira Portátil Gaia Adventure, which allows waste to be transported more safely and discreetly. For runners, that kind of solution may be too bulky, but it serves as inspiration: what matters is that the athlete has a pre-planned system that is durable, well-sealed and kept separate from other items in their vest or pack.
In simpler situations, a heavy-duty ziplock bag or a small dry bag can serve part of that purpose, especially for carrying used toilet paper. But when the need involves human feces, the ideal is to consider systems specifically designed for human waste, with a secure closure and, when possible, absorbent or neutralizing material, such as WAG Bags or similar solutions.
Unfortunately, these products are still not easy to find in many countries. For those traveling to the United States, for example, it may be worth buying a few units and keeping them in the pack or vest as emergency items for long training runs, quick crossings or races in sensitive locations.
The main point is that this needs to be planned in advance. Just as runners think about gels, water, a wind jacket, lighting and navigation, they also need to think about what they’ll do if they need to defecate during the course.
It’s not a minor detail. Human waste is also waste. And in many environments, leaving it on the trail — even buried — can contaminate soil, impact water sources, degrade the experience of other users and create a management problem for the natural area.
In other words: it’s not enough to think about gels, water and shoes. You also have to think about poop.
For organizers, this point is equally important. Restrooms at the start and finish are the bare minimum. In longer races, strategic aid stations should also account for this need. And when the course passes through sensitive areas, guidance on human waste needs to be clearly communicated before the race.
Races without disposable cups
Reducing waste also comes down to what happens at aid stations.
Many trail running races have already stopped providing disposable plastic cups. This reduces waste generation and educates athletes to take on part of the responsibility for their own hydration.
In Brazil, WTR is a good example. In the race manual, the organization states that it does not provide disposable cups, that all athletes receive a collapsible silicone cup in their kit and that, for certain distances, it is mandatory to start with a hydration vessel. The same material outlines waste management practices, a Zero Waste goal, trail cleanup before, during and after the race, donation of sports equipment and other sustainability initiatives.
For the runner, this means leaving home prepared. That could mean a soft flask, a bottle, a hydration system, a cup provided by the race or an ultralight collapsible cup. One example is the Curn Collapsible Cup by CNOC Outdoors, a flexible 250 ml cup that is compact, foldable and weighs around 11 g, designed for runners and outdoor enthusiasts who need a lightweight solution for drinking at water points or mixing hydration tablets.
What matters most is not the cup model. It’s the shift in mindset. Instead of expecting the race to provide everything, the athlete becomes part of the solution.
“When we don’t offer disposable cups at hydration points and instead include a collapsible cup in the kit, the runner stops being just a spectator of a sustainability message and becomes part of it. They need to prepare, bring their own vessel, think about their own hydration and understand that their presence in that environment also involves responsibility,” explains Gabriela.
For her, this behavioral shift promotes education in a practical way. “The athlete realizes that small individual decisions, when applied at scale, significantly reduce the event’s impact.”
At one of WTR’s race stages, a survey showed that 94.2% of participants noticed some of the good practices implemented, and 33% specifically mentioned the fact that no disposable cups were provided.
Principle 4 — Leave what you find
In trail running, this means:
don’t take natural souvenirs, don’t alter the trail and don’t treat the environment as a disposable backdrop.
This principle may seem less obvious to runners, but it shows up in many small details.
Don’t pick flowers, fruits, seeds or plants. Don’t take rocks, shells, bones, feathers or other natural elements as mementos. Don’t interfere with historical or cultural structures. Don’t remove official signs. Don’t build cairns, improvised arrows or stone markers. Don’t “improve” the trail on your own during a training run. Don’t push through vegetation to make a descent or a pass easier.
Illustrative image generated by artificial intelligence.
It’s also worth thinking about the digital world.
Not every route recorded on GPS should become an invitation for others to repeat it. In some places, sharing tracklogs of informal access points, shortcuts, unauthorized trails or sensitive areas can increase impact. Routing apps, segments and social media are powerful tools, but they can also popularize paths that shouldn’t receive traffic.
For organizers, “leaving what you find” means removing everything placed on course for the race: flagging tape, signs, arrows, banners, temporary structures, finish area materials, ground markings and waste from aid stations. All signage must be temporary, removable and planned so as not to leave permanent marks.
“When a race occupies a mountain, a trail, a beach or a conservation unit, there is a great responsibility to preserve that territory and to return that space in as good a condition as possible,” says Gabriela.
A well-organized race, therefore, should leave no trace on the trail.
Principle 5 — Minimize campfire impacts
In trail running, this means: managing any heat source associated with training, the race or the event’s infrastructure, especially in dry or sensitive areas.
For those who are simply running, this principle may seem remote. After all, runners don’t usually build campfires during a training session or a race. But the logic behind the principle remains highly relevant: avoiding damage caused by fire and other heat sources in natural environments.
In trail running, this impact can appear in other ways. Some races involve a start and finish area, support bases, social areas, camping, overnight stays, crews, staffs, volunteers, spectators and on-site food. In longer events, there may also be support kitchens, camp stoves, grills, generators, lighting, heaters or temporary structures.
There is also the risk of fire. Cigarette butts, improperly used camp stoves, improvised grills, unauthorized campfires, sparks, poorly extinguished embers or any heat source during dry periods can cause enormous damage. In some regions, a small act of negligence can trigger a large-scale wildfire.
For athletes, the application is straightforward: don’t make improvised fires, don’t discard cigarette butts, respect local restrictions, avoid any unauthorized fire source and encourage support crews, family members and friends to do the same. Even those who are only spectating at a race are part of that event’s impact.
For organizers, this principle requires planning the race venue, controlling food areas, establishing clear rules for camping and support crews, briefing volunteers and spectators, respecting local regulations and paying special attention during periods of drought or high fire risk. Any use of kitchens, camp stoves, grills or generators must be planned, authorized and controlled.
In other words, in trail running, Principle 5 is not limited to the traditional campfire. It addresses a broader question: what risks and impacts can heat sources associated with the activity generate in that environment?
Even when runners aren’t camping, a race can create a significant structure around the trail. And that structure must also follow a minimum impact logic.
Principle 6 — Respect wildlife
In trail running, this means: running without chasing, startling, feeding or interfering with animal behavior.
Runners move fast, often in relative silence, early in the morning, at dusk or at night. This increases the chance of unexpected wildlife encounters.
That’s why it’s important to observe wildlife from a distance, not chase animals to photograph them, not attempt to touch them, not feed them, not leave food scraps behind and reduce unnecessary noise in sensitive areas.
Illustrative image generated by artificial intelligence.
It’s also important to respect temporary trail closures due to breeding seasons, nesting, the presence of young animals, fire risk or environmental recovery. A closed trail is not a challenge for the “hardest of hardcore” athlete. It’s a management decision that must be respected.
Food scraps also fall under this principle. A fruit peel, a piece of energy bar or food left on the ground is not harmless. It can attract animals, alter behavior and create an association between human presence and food.
For organizers, this principle involves course selection, time of year, communication with land managers, noise reduction in sensitive areas, waste control at aid stations and clear guidance to athletes.
Wildlife is not a supporting cast for the race. It was already there before the starting gun.
Principle 7 — Be considerate of other visitors
In trail running, this means: remembering that the trail doesn’t belong only to runners.
The trail may be used by hikers, families, guides, pilgrims, cyclists, horse riders, local residents, researchers, forest firefighters, park rangers and other runners. In a race, the athlete may be wearing a bib, a chip and chasing a time goal. But none of that turns the trail into an exclusive track.
Leave No Trace recommends that runners announce their presence, ask to pass politely, wait for a safe spot to overtake, yield to those going uphill and pay special attention around horses and other trail users.
In practice, this means slowing down when necessary, not startling people from behind, avoiding headphones at high volume, respecting shared trails and accepting that losing a few seconds is part of a healthier coexistence.
Performance doesn’t justify rudeness. Competition doesn’t eliminate respect.
Illustrative image generated by artificial intelligence.
For organizers, being considerate of others means engaging with local communities, notifying regular users of the area, avoiding blocking access without communication, respecting residents, briefing staffs and athletes, managing traffic, noise and parking and tending to the relationship with those who live or work in that territory.
A trail running race doesn’t take place only in a landscape. It takes place in a place. And places have histories, rules, communities, other uses and other people.
A race can also educate
When a race genuinely incorporates the principles of Leave No Trace, it stops being just a sporting event. It becomes an opportunity for formation.
This can appear in the athlete handbook, the technical briefing, on social media, at aid stations, on temporary signs and in the training of staffs and volunteers. Simple messages can make a big difference:
“Stay on the trail.”
“Go through the mud, not through the vegetation.”
“Carry your gel wrapper back.”
“Respect wildlife.”
“Don’t cut the course.”
“Your trash finishes the race with you.”
The International Trail Running Association (ITRA) presents its Green Charter as an initiative to mobilize the trail running community in reducing the sport’s environmental impact, reinforcing that this responsibility involves organizers, participants, volunteers, sponsors, suppliers and partners.
That is the central point: a race shouldn’t just pass through a natural area. It should leave the trail, the community and the runners better than it found them.
Running lighter also means leaving less impact
In trail running, there’s a lot of talk about running light. Lighter shoes, smaller packs, carbon poles, compact jackets, flexible bottles. Less weight, more speed, more efficiency.
But there’s another kind of lightness.
Running light also means passing through a trail without widening it. It means carrying back everything you brought. It means having a plan for your own waste, including human waste. It means not cutting corners, knowing when to wait to pass and choosing races that respect the places they pass through.
It means understanding that nature is not an obstacle, a backdrop or a disposable product.
Trail running only exists because there are trails, mountains, forests, parks, communities and landscapes capable of welcoming us. If the sport grows without care, it compromises precisely what makes it special.
Chico Santos, elite trail runner and coach, certified in Leave No Trace – Level 1 Instructor, often uses the phrase “The more people on the trail, the more trail we carry within” (Quanto mais gente na trilha, mais trilha na gente). And feeling part of nature comes through education, respect and awareness.
As organizer of Training Camps through CS Experience, Chico’s goal is to include Leave No Trace workshops to broaden knowledge of minimum impact techniques among trail runners.
“Although many trail runners are already aware, there are still irregular practices — mainly the habit of leaving small bits of waste along the way. It’s important to get information out there, especially to those who are just starting, so they begin with that awareness already in place.”
Beyond spreading knowledge at his events, Chico disseminates the principles of Leave No Trace through his social project. “I train three athletes who are already standing out, and I work with them on awareness of the importance of not deviating from the route to gain time or avoid obstacles, as well as respect for other runners.”
In trail running, Leave No Trace doesn’t limit the experience. On the contrary: it helps ensure that the experience continues to exist.
Running in nature is a privilege. Taking care of it is part of the course.
Want to go deeper into Leave No Trace?
Gear Tips is a corporate partner of Leave No Trace and works to spread minimum impact principles through articles, videos, courses and educational materials aimed at practitioners, guides, leaders, instructors, event organizers and outdoor industry professionals.
To keep learning, visit the content on Leave No Trace on the Gear Tips blog!
Those who want to go even further can explore the Leave No Trace – Level 1 Instructor course, part of the Gear Tips CAPACITAR Program. The course trains facilitators capable of teaching minimum impact practices through talks, workshops, introductory courses, educational activities and outreach in parks, schools, clubs, tour operators and outdoor communities.
Leave No Trace is not just about not leaving trash. It’s about developing a more conscious, responsible and respectful relationship with the places we pass through.
This post is also available in: Português (Portuguese (Brazil)) Español (Spanish)
