Trail running has doubled in three years, and it is almost never run alone

Forty-two thousand members of the French Athletics Federation now list trail running as their main activity, a rise of ninety per cent in three years according to the Finishers barometer published with the Union Sport et Cycle. Trail is no longer the preserve of stubborn mountain people. It has become one of the most ordinary ways of running in France, and it is also the one that people are least willing to do on their own.

Has trail running become a mass sport?

The French Athletics Federation broke its all-time membership record in December 2024, passing the 316,751 registrations of 2019, and counted more than 321,000 members by mid-January 2025 across 2,535 clubs. Inside that total, trail is the fastest-moving segment. The 42,000 people who list it as their main activity are only a fraction of the membership, but their number has nearly doubled while the federation as a whole gained a few percentage points.

The race calendar tells the same story. France staged 13,320 races across all disciplines in 2025, producing 4.12 million recorded results, an all-time high. Of that total, 5,900 events were trail races, up twenty per cent in a single year, and they generated 1.44 million results. In other words, roughly a third of all running results recorded in France last year were earned on trails.

What those figures do not say, and it needs saying on their behalf, is that the reported growth of trail running varies by a factor of two depending on the source and the period chosen. Some publications quote a hundred and fifty per cent rise over ten years, others three hundred. The absolute numbers, on the other hand, are solid. Those are the ones worth reasoning from.

What does the size of trail fields reveal?

A trail race gathers an average of 215 finishers, against 439 for a road race, according to 2024 industry data. The average across all disciplines rose from 260 finishers per event in 2024 to 310 in 2025.

That figure of 215 is more interesting than it looks. It means that a trail race, in its usual format, is an event where you keep crossing paths with the same faces, where the aid station is a conversation rather than a counter, and where you rarely leave without having spoken to someone. The social density of a two-hundred-person trail race has nothing in common with that of an urban ten-kilometre lining up three thousand.

Where do women stand in trail running?

Women made up 37 per cent of participants in French races in 2025, against 28 per cent in 2015. The progression is clear and continuous. It is not uniform, though: according to Miles Republic data from 2024, the share of women reaches 40 per cent on the road and falls back to 33 per cent on trails. On ultra formats, a September 2023 study by the Union Sport et Cycle covering around two thousand runners records 91 per cent men.

So there is a gap, and it widens as the distance grows. The reasons are many and poorly documented, but one of them is perfectly measurable: setting off alone on an isolated trail does not involve the same mental arithmetic for everyone. A survey run in December 2025 by Censuswide among 3,000 French adults for SportsShoes reports that 57 per cent of women runners have felt unsafe during a run, against 50 per cent of men, and that 70 per cent of respondents only run in daylight, 62 per cent tell someone before leaving and 56 per cent stay in lit areas. Those three strategies describe exactly what running with someone else makes unnecessary.

Does running in nature really do you good?

The idea that running in nature does more good than running indoors has become a commonplace. It rests on real work, but work that is less clear-cut than the repetition suggests.

A network meta-analysis published in 2026 in Frontiers in Public Health, covering 15 randomised controlled trials and 809 participants, finds a significant effect of exercise in a natural setting compared with no exercise, and a significant effect of the natural setting compared with an indoor one. Indoor exercise compared with no exercise, however, does not reach significance in that same model. The authors themselves flag very wide confidence intervals, a single multi-arm trial linking the indoor condition to the control group, and an almost complete absence of long-term data.

A longitudinal review published in 2023 in IJERPH, across 10 trials and 343 participants, is more cautious still: out of 99 comparisons, only 25 are statistically significant. All 25 point the same way, in favour of the outdoors, but the body of trials carries a high risk of bias.

The honest conclusion is therefore this: the available data lean in favour of running outdoors, without allowing anyone to quantify the benefit seriously. Be wary of any article that hands you a precise percentage on this point.

What is the real risk when you take up trail running?

The most solid statistic in this whole file has nothing to do with sociability or scenery. A meta-analysis published in 2015 in Sports Medicine, drawing on 13 original studies, establishes an incidence of 17.8 injuries per thousand hours of running among novice runners, against 7.7 among experienced recreational runners. Hour for hour, a beginner gets injured more than twice as often.

And injury takes people out of the sport. A Dutch study published in 2019 in the Journal of Science and Medicine in Sport followed 774 beginner runners over twenty-six weeks: 29.5 per cent had stopped running by the end of that period, and injury accounted for 48 per cent of those stops. That study is Dutch, it covers a supervised programme, and there is no French equivalent. It gives an order of magnitude, not a national truth.

What that changes for you is simple. The question is not whether you will make it up the climb. It is whether anyone will stop you from stacking too much elevation too fast in your first three months. At that stage, a more experienced partner is a prevention device before being company.

What does running with others bring to trail?

We need to be precise here, because the subject is saturated with unverified claims. A meta-analysis published on 15 April 2026 in Nature Human Behaviour, covering 71 studies, 523 effect sizes and more than 22,000 participants, finds no significant difference between individual and group interventions in the volume of physical activity produced. The equivalence test is even significant on that specific outcome. So nobody can promise you that running with others will make you run more.

But the same study shows a significant advantage for the group on functional capacity, meaning strength, balance and mobility, and leaves the psychosocial side undetermined, neither equivalent nor different, for want of sufficient precision. And an earlier meta-analysis, published in 2006 from 44 studies and 4,578 participants, establishes a strong difference not between practising alone and practising with others, but between a group where people matter to one another and a mere gathering of people doing the same thing in the same place.

That is the real dividing line. Running next to someone changes very little. Running with someone who notices your absence changes a great deal.

How do you start trail running from scratch?

Pick a short trail race, twenty kilometres or less, within an hour of home, and enter it with someone rather than on your own. Recce the course in training at least once, walking the technical sections. Accept that you will walk during the race, which is the norm rather than the exception on this terrain. And if you are starting out, build your progression on time spent rather than on elevation accumulated, because it is the second of the two that wrecks a newcomer’s legs.

That leaves the part nobody solves for you: finding the person to set off with. That is exactly what Smatchy does, by putting you in touch with runners at your level and in your area, for Sunday’s outing rather than for the whole year.