On Ilkley Moor in west Yorkshire on a Tuesday evening in May, 200 people milled about in glorious sunshine, ready to run the five-mile Jack Bloor race over moors recently blackened in a fire, but still beautiful. The air was clear, the good cheer was tangible, the moor birds clucked high up on the hill that we would soon have to climb.

We gathered at the start, and everything proceeded as it does at fell races: someone gave inaudible instructions and then said something like: “Right then, off you go.” Fell running – making your own way between checkpoints over moorland, hill or mountain – thinks itself a pure yet humble sport. Fell runners have no truck with fancy gear like road runners do, or shiny poles like ultrarunners. We don’t even need paths. Some of this purist attitude comes from where we run, through thigh-deep bogs and leg-scraping bracken, down scree and boulders at the pace of a fearless child. We run against the elements as much as against other runners.

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Yet, at the start of the race, two things happened: 400 feet started to move, and 200 fingers pressed a button on a wristwatch equipped with GPS, setting the devices to record. The moor birds’ cheeps were now accompanied by beeps. When it comes to tracking and measuring runs, and being obsessed with data, we are right up there with the rest of the field. But tracking and measuring were just the start. Soon after finishing the race, most of the runners would upload that GPS data to a digital platform that has changed the world of amateur sport. The fell runners knew, as millions of people worldwide do, that if it isn’t on Strava, it didn’t happen.

Strava is a fitness and sports tracking platform that launched in 2009 and bills itself the “number one app for runners and cyclists”. As long as you have a smartphone, watch or bike computer that records your activities using GPS, you can sync it with Strava, then upload your run, cycle, ski or almost any other activity, and be rewarded with astonishing levels of data analysis. For an amateur, the data available from Strava is like having a Team GB coach in your phone, for free.

Strava tells me how fast I ran in May 2015 or last Thursday, and how much improvement I have made. Every run I do is recognised and automatically matched to anyone else who has run the same route, or part of it. Athletes – as Strava flatteringly calls its users – can create a “segment”, a portion of a route, perhaps featuring a hill or a stretch of lake, against which other athletes can then match their own efforts. In my local park, I can see how my 2017 self did on a segment someone has named Up the Bloody Hill, or on Stairway to Heaven (actually steps to the car park), or on #Weeeeeeeeeee! My efforts can be scored on “leaderboards” so that I can compare myself with myself, with my Strava followers and friends, or with strangers from Korea to Kansas.

Because of Strava, I know how many miles my shoes have covered and whether I need new ones, as the app will email me to tell me (without sending me ads for shoes). After a race, I can launch Strava’s Flyby feature, an ingenious interactive map, and watch my digital self rerun the race route alongside anyone else who ran it. It is addictive, to watch these ghosts in the machine, and see where they got away, or where I caught them up, to see if they went wrong and how badly. For my efforts, I can be given “kudos” by anyone who follows me – the Strava “like”, signified by a thumbs up – and I can do the same for them. I can leave supportive comments and add photos. I can change the name of my activity from the default “morning run” or “lunch ride” to something witty and punning, and it is one of the unwritten rules of Strava that I should.

Because of Strava, I also have a ringside seat into how elite athletes train and race: more than half of the Tour de France peloton last year uploaded their stages. I can follow the training of Kílian Jornet, the world’s best mountain runner, or champion distance runner Aly Dixon. Strava has been downloaded by 49 million people in 195 countries, and the company claims it attracts a million new users a month. In total, these people upload 25 activities a second, or 15.3m a week. They share 4 million photos a week and last year gave each other 3.6bn kudos. In the reward loop of Strava, activities get kudos, which encourages more activities. Adding funny names, emojis or photos increases the number of kudos by up to a third. More kudos, more exercise. The more people share their data, the better the experience.

There are now many thousands of apps available that can track your weight, calorie intake, hormones, sleep patterns, insulin levels and water intake. The number of Americans who own a smartphone (defined as a device that combines a phone with some computing ability and internet access) jumped from 56% of the population in 2013 to about 80% today, or 299 million. There are apps that buzz you when you slouch, or remind you to stand up. You can buy headbands and clip-on cameras that monitor your heart rate, temperature and menstrual cycle. Market projections state that this year, the health and fitness wearable tech market will be worth $34bn.

The essential goal of any tech platform is to make you use it again. This is called “stickiness”. But one step beyond stickiness is community: the key is to embed a tech platform into someone’s life, including their friends and wider circle of acquaintances and fellow athletes they haven’t even met. Group encouragement is proven to have a positive effect on fitness: users who belong to a club (including virtual ones) upload three times more activities than non-members.

Ben Mounsey is a top mountain runner from Yorkshire, and formerly a school photography teacher in Elland, near Halifax. Before he discovered Strava, he was a good enough runner to make national teams. “But I didn’t have any focus. I was just running on natural fumes,” he says. He never kept a diary and could not remember his run times. In 2014, a friend mentioned Strava. He signed up, got a GPS watch and started recording his times. “I became obsessed, from day one,” he says.

I don’t consider myself addicted to Strava: I don’t check in unless I’ve done an activity. I don’t get notifications. I have never created a segment and don’t know how to. I would never log into Strava just to browse. And yet, looking at the data has become an essential part of my exercise regime. Once, my phone broke when I was travelling without a computer to hand, and my first action when I got a new one was to manually upload to Strava the runs I had done without it. My data shows I have done 171 runs in the past 12 months: my memory has recorded that I did fewer than half a dozen that weren’t logged. What I don’t know is how a middling, menopausal fell runner, who only began running at the age of 41, and will never win much, got to care so much about any of this.

In the mid-90s, two former college friends, Michael Horvath and Mark Gainey, met to discuss an idea. They had been competitive rowers at Harvard, and both missed rowing life: its competition and camaraderie were hard to recreate when they no longer had time for team sports. Gainey and Horvath’s idea was to create a “virtual locker room” where people who exercised alone could still find a community. But the technology wasn’t good enough to build what they wanted. Instead, they founded Kana, a company selling email and marketing software which, at its height, was valued at $10bn (£7.7bn).

In 2006, they came up with the idea for a social network for athletes, with “athlete” meaning anyone who took fitness seriously. (Strava’s CEO until November last year, James Quarles, defines an athlete as “anyone who sweats”.) They chose the name Strava, from the Swedish “to strive”. By then, technology had progressed enough for people to carry GPS devices in their pockets, and strap on lightweight heart monitors.

Gainey and Horvath had observed that digital sharing was rising at the same time as communal activity was declining. They targeted what they called “avids” – cyclists who rode frequently – and hoped that word would spread. From the beginning, the big hook was the leaderboard, a ranking of anyone who has cycled a particular route. This was not unique, but was borrowed from online gaming. The difference was that this scoreboard was linked to real-world physical activity. Strava offered the competitive draw of segments and the gratification of kudos. There were also rewards: as the quickest rider of any segment, you would be labelled King of the Mountain (KOM) or Queen of the Mountain (QOM). That these prizes are fleeting, lasting only as long as it takes for someone to beat your time, only increased the addictiveness.

These features – lures, rewards, competition – are now considered standard in gamification, which apps use to get us to return. Strava’s ace was to combine the competitive appeal of the segment with a community of likeminded people who knew how much it meant to come back from injury or miss a personal best. Add an interface that is widely accepted to be clever, clean and extremely simple to use – along with the increasingly rare situation of being free from ads – and Strava was a hit.

Facebook Twitter Pinterest Strava art: a Welsh dragon created on the app. Photograph: PR

The first Strava user was David Belden, a cyclist from California. (He is still on Strava and, in 2019, he covered 1,455.8 miles and climbed almost 40,000 metres.) For the first years, the main users of Strava looked similar to Belden, in that most of them were male and on a bike. Growth was steady. In 2011, Strava offered a separate running app, before merging everything in 2014. Strava staff like to call their product “agnostic” because it doesn’t care what device or app is used to upload data. “We are the Switzerland of tracking platforms,” says Gareth Nettleton, vice-president of marketing at Strava’s UK base in Bristol.

Strava accepts data from devices made by Suunto, Zwift, Garmin, Polar, Fitbit or Apple, and is equally broadminded in which activity it allows you to upload. The current menu includes in-line skating, rock climbing and standup paddling. (Although Public Health England includes gardening as an accepted physical activity, Strava does not.) Strava’s annual report of stats suggests that still men make up 75% of users. Women’s most popular activity is running; men still prefer cycling.

Strava data has shown that older people work out more than younger; that women are better at pacing a marathon than men; and that cyclists over the age of 50 go 50% further than cyclists in their 20s on an average ride. Strava has also given rise to another trend. Since others can look at their routes, athletes have started making Strava performance art – riding or running a route that, once mapped, becomes an image or message. Top efforts so far: a New Forest pony, a marriage proposal (she said yes in the comments) and an impressive Father Christmas, created by “pedalling Picasso” Anthony Hoyte from Cheltenham (his “Fowl Play 2” image of several birds required a ride of 51 miles and a climb of 1,200 metres).

Strava is not the most-used fitness app in the world. Runkeeper has 50 million users; Runtastic claims more than 147 million registered users and is popular in Europe. Other strong competitors are MapMyRun, Endomondo, Nike+ and Google Fit. Most offer some variety of tracking, recording and sociability. Many are owned by big sports shoe and clothing corporations (Asics, bought Runkeeper in 2016 for $83m; Under Armor bought MapMyRun and its 20 million users for $150m).

Strava does not sell clothes or shoes. Quarles, former CEO, came from Instagram, where he had introduced ads, but there are no plans to do the same at Strava. More important is building goodwill in the community. “I worked for a long time at the intersection of technology and communities,” he told me on the phone from the US last spring, “and at how technology brings people closer together, not turns into this dystopian thing of them spending time apart.”

Strava users may start as loners, only tracking their own activities, but the hope is that they will soon be hooked into tracking friends and peers, and that this will push them to go further and faster. But the friendly competition of a supportive, likeminded community can sometimes lead to darker impulses.

Mounsey, the mountain runner, found the segment a powerful addiction. For months, he “went crazy” trying to win every segment within a 10-mile radius. “Everyone hated me for a long time in Elland.” Once, he says, a clubmate took a segment off him on a local steep hill called Trooper Lane. “I couldn’t believe it. I tried not to be bothered by it, I saw it at 7.30pm and by 8pm I was analysing it.” The next morning, he got up an hour earlier than normal, ate nothing, stopped off at Trooper Lane, did a hard session of 35 minutes, beat his clubmate by five minutes, then went to work and fell asleep in the classroom. “I felt really ill, I’d pushed myself so hard, all for a bloody segment, for male pride,” he says. Then adds: “I’m portraying myself as a bit of a psychopath here, aren’t I?”

When he found himself running miles on a Sunday just because he hadn’t reached his self-imposed weekly target, he pulled back. “I can see the good and bad in Strava.” (He’s still on it, though. Disclaimer: he is an unpaid Strava ambassador.)

Strava says segments don’t just appeal to men, although I have never seen a female runner suddenly set off at speed shouting “segment!” as a male clubmate once did. This pursuit of a record can encourage dangerous impulses. In 2010, a cyclist named William “Kim” Flint was killed chasing a fast downhill segment when his bike, travelling at 40mph, crashed into a car in Oakland, California. (His family sued Strava and lost.) Forbes magazine called this “a quantified-self fatality”. Mountain bikers frequently report being pushed off trails by other bikers descending at speed and yelling “STRAVA!”. In 2016, alarmed by the speeds recorded on Strava segments, a council in Los Altos, California, banned mountain bikers from Byrne Preserve. Strava now lets users flag a segment as hazardous, and its terms of service absolve the company of any responsibility for “known or unknown risks associated with these activities even if caused in whole or part by the action, inaction or negligence of Strava”.

Once, I got a CR – course record, the equivalent of Queen of the Mountain – on a random stretch of trail in south-west France. This is a rare enough event that I remember it vividly. Within hours, a Strava email alerted me that I had lost the record; I immediately logged in to see who had taken it. Then I checked how fast she had run it and compared her time to mine. Then I went to her profile and checked how old she was and all her other activities. A year later, I am still planning to go back to that unremarkable forest track up the hill from Belesta and sprint up a random 400 metres as fast as I possibly can.

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Strava forums have plenty of fuming users enraged about cheating. E-bike users who “forget” to mark their rides as an e-bike and end up on leaderboard are a growing problem. Taking your GPS watch for a drive is another. In Hong Kong, one user wrote on Strava’s forum: “A large percentage of segments is polluted by people using cars or electric scooters.”

Some of this is accidental, as e-bike users have to manually change a setting on Strava to mark their rides as assisted. Some of it is not. An e-biker named Matt May has a profile picture of a bottle of vodka attached to his bike, and delights in annoying Strava purists. There are legitimate third-party apps that claim to help people improve their Strava stats by alerting them, for example, to wind conditions. Then there was the short-lived website Digital EPO (named after erythropoietin, a common illegal drug in sport) that allowed people to alter the GPS data to show they had gone faster than they had in reality. This inflamed plenty of cycling and running forums.

On his podcast, the California-based ultra-endurance athlete Rich Roll hints at why what people post on Strava matters: “There’s something uniquely special about being privy to the daily grind of my favorite multi-sport athletes. Their transparency holds me accountable. In turn, I help hold my community accountable. And openly sharing our collective fitness experience – the highs and the lows – makes all of us better.”

I did once report a cheat. Strava lets you do this by “flagging” a suspect activity, such as a ride or run that has clearly been done in a car, or on an e-bike. Why did I care? It was a woman who had apparently run a stretch of my local park in about 10 seconds. I cared because I had just run that same stretch and it had taken more than two minutes. I cared because it was physically impossible to do what her upload said. I am never going to be an elite athlete. I am competitive, but only with myself, and only because I want to disprove the idea that a 50-year-old woman cannot improve. Yet, suddenly, when I saw that improbable segment, I was seven years old again and someone had cheated in the playground. My emotions had the purity of childish rage, that white heat of unfairness. I flagged the segment, which meant she would have been given an option to delete it, which she did. I’m not sure if I felt bigger or smaller for doing it. (I’m lying. I would do it again.)

Strava is growing, though probably not as fast as the company would like. Over 80% of Strava’s users are outside the US, and Brazil is now its second biggest national market after the US. It is also big in the rest of Europe and getting big enough in Japan to have a country representative there. These country reps can deliver insights into how the world exercises.

Brazilians are social, and they also love sport, making Brazil a perfect society for Strava (they also like to work out with their family, unlike any other country). The French are equally into running and cycling; Germans prefer bikes. Strava’s yearly data report offers other revelations. The most active day of 2018 for German cyclists was 6 May; for French cyclists it was 9 September. Americans ran more on 23 November than on any other day in 2018; Japanese runners were busiest on 16 September. Globally, most people exercise on a Sunday except in the UK and Ireland, where we prefer Tuesday. Runners talk about beer in their activity uploads; cyclists talk more about coffee. From Strava data, the media concluded that the second week in January is “quitters’ week”, when newly active users give up (although women will last two days longer than men).

This data also offers a “heat map” – a record of activities in any given area. In 2018 Strava’s global heat map, a record of 1bn activities worldwide, accidentally revealed the location of secret US military bases, because personnel had uploaded their activities to Strava and failed to opt out of heat maps. Fitness tracking data can have other uses: one user concluded her boyfriend was cheating by noticing how often his Strava rides were done in the company of another woman. Fitbit and Apple Watch data has been used to solve murders (in one case, showing that the victim’s heart rate had spiked during the suspect’s visit and been silent thereafter).

Those that opt in to Strava heat maps become a saleable product. Under a project called Metro, Strava sells anonymised data to cities about where and when its users ride and run and exercise. More than 70 cities have used Metro in the US states of Colorado, New Hampshire, and in the UK; as have academic and non-profit organisations such as Glasgow University’s Urban Big Data Centre. Strava offers a paid subscription called Summit with additional features – more heart data, the ability to filter leaderboards by age and weight, and a useful location-tracking feature called Beacon – for about £4.50 a month. The company doesn’t release figures about how many of its athletes pay for Summit, but it is thought to be a percentage in single figures.

Facebook Twitter Pinterest A Strava heat map of the UK. Photograph: Strava

Athletes who use products from companies with whom Strava has set up commercial partnerships now find their activities attached to a banner proclaiming that they “ran with Suunto” or cycled with Zwift. For the first time this year, Strava’s Year in Sport report included a section on “the world’s hottest gear”, a list of the most popular brands used by people on the platform. It is not an ad, but it smells like one. “Wahoo doesn’t sponsor me,” said one user in Strava’s forum, among many objectors. “There is no reason I should be forced to sponsor them.”

When we spoke in early 2019, Quarles was optimistic that profitability wasn’t far off, but he was suddenly replaced in November 2019 by co-founder Michael Horvath, with Mark Gainey also returning to an active role. Strava also lost its high-profile chief technology officer, Stephanie Hannon, who had been digital chief for Hillary Clinton’s presidential campaign, after only a year. There are a few options for Strava to make money: becoming a subscription-only service, selling up, selling its users to advertisers, or selling more data than it does currently (Metro data is anonymised, and Strava’s terms of service say that users own their data, but that they grant Strava a huge licence to use it).

Perhaps the golden years of this clever, uncommercial app being available for free are numbered. But Strava is still a beacon of positivity among the bile and manipulation of other social media. Trolling is rare and usually only takes the form of excessive kudos from randoms – and what’s wrong with that? I get regular abuse on Twitter; on Strava, I have never had anything but encouragement. The company says its currency is effort, but it is also largely goodwill. The platform’s privacy controls now are good enough that I can hide my home and my place of work, and I can stay off leaderboards. I could stay off Strava, too, but I don’t intend to. It is a guidebook and a corkboard (posting photos, Strava believes, enables powerful “memorialisation” of activities). It is training log, chat room and map room. And in these days of public carping and rage, it is something I prize more than race prizes: it is a refuge.

Richard Askwith, a British writer and fell runner, is the author of Running Free, a book about the over-commercialisation and datafication of running. He gave up running with a smartwatch years ago. “I think if I was constantly wanting to tell other people about my runs I would be losing out on the experience of the run itself. If you’re running off-road, then you’re inhabiting your environment and you’re sensing how your step feels and you’re thinking about where your next step is going to go. Then if you want to think about how much effort you’re putting in, you just sort put your foot on the pedal a bit, but it’s all subjectively measured.”

Or, as one cyclist who had given up quantifying wrote: “I remember when cycling used to be fun.”

Facebook Twitter Pinterest Rose George during the Shepherds Skyline fell race in the Calder Valley, West Yorkshire. Photograph: Stephen Smith Photography

The British Medical Journal provides a service assessing some fitness apps. Its entry on Strava lists the obvious pros (it’s free, it’s easy to set up, it encourages users to push harder than they would alone). The writer also warned of the cons: “Owing to the competitive nature installed in users of the app, risk-taking behaviours may be increased that could lead to musculoskeletal injury or road traffic collisions.” Also, “one may forget what a leisurely bike ride or jog used to feel like.” A paper presented at the Royal Geographical Society in London in 2013 by Dr Paul Barratt of Staffordshire University suggested that Strava was, perversely, making group rides antisocial, as riders concentrated on winning segments from virtual strangers rather than focusing on their fellow riders in real life.

Fell runner Tim Dempsey gave up using technology on the hills three years ago. “Thinking forward to the completed run on-screen while running, only to finish and use the screen to look back. It removes you utterly from the moment. Two years on. I still look at my naked wrist for cues.”

“I love it and hate it in equal measure,” says the runner and coach Anji Andrews. “It’s great for logging training and keeping track of pace, routes, mileage. It’s horrific in being, to many, just an online log of excuses and encouraging comparison (the thief of joy).”

Recently, on occasion, I have forgotten to wear my GPS watch at races and runs. At races, I experienced mild concern: if it is not recorded, then how will I know how fast I have run? How will my miles count towards my yearly 1,000-mile target? But then I set off, on a recreational or competitive run, and something happens. I feel freer. I run across moorland and stop to look around, and don’t worry about pausing my watch, about someone later looking at my data and seeing that I stopped for a gawp of the purple heather and the eerie calm of the stone circle. I walk for a bit and revel in not being recorded. No one is looking. No one cares.

At the biggest race in my calendar, the Yorkshire Three Peaks, I didn’t dare leave my watch behind. I had certain cut-offs – set times – to reach, so I needed to know what the time was. But as I set off up Pen-y-Ghent, I did something strange, and turned my watch to the inside of my wrist. That made it slightly harder to check, and so I hardly checked it. I ran according to feel, as the training term goes, and despite hailstorms and cramp and only looking at my watch three times over 23 miles, I got the best time I had ever done.

Maybe I had learned to pace myself so well by using tech that I could do it without? I was a fell running equivalent of Luke Skywalker in his X-wing fighter, switching off the targeting system and feeling the Force. Unchained from data, I felt free and powerful. And within a couple of hours of finishing, after sitting among my real life running friends in the race marquee, all of us glowing with achievement, and scoffing stew in likeminded company, I uploaded the run to Strava. How else would I get any kudos?

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• This article was amended on 15 January 2020. An earlier version said that in November 2019, Mark Gainey took the position as Strava’s CEO, with Michael Horvath returning to an active role in the company. In fact it was Horvath who became CEO, and Gainey who returned to an active role in the company. This has been corrected.