The rise of marathon technology

The London Marathon is no stranger to electronic technology. Even 15 years ago you could hear the near-synchronised beep of sports watches being fired up as scores of amateur runners stepped past the starting lines in Greenwich and Blackheath on an April morning.

Since then, smartphones have joined sugary gel packs, energy drinks and GPS-enabled watches as part of the common armoury of the long-distance runner as well as a near-essential item for people hoping to catch a glimpse of family and friends as they make their way along the 26.2-mile course. In the background, the technology deployed to help support the race has grown.

The London Marathon decided to launch a smartphone app for the race eight years ago. Despite being tested on other events and deployed just for the Apple iPhone, the sheer scale of the 2015 London event proved too much for the servers responsible for delivering data to the app. Some 20,000 people downloaded the software in the two days after the app appeared in the App Store. But another 100,000 grabbed a copy in the 24 hours before the race and, as many of them attempted to find out where runners were found, the app just did not respond.

The race organiser directed users to the website for up-to-date runner timings. The following year saw a change in app provider, with TCS becoming the technology partner. For subsequent events server capacity expanded significantly to cope with rising numbers and the inclusion of Android as well as Apple devices. In 2019, the organiser recorded 465,000 downloads of the official app, and some 120,000 concurrent users at the peak.

Off-course, the market for software connected to the event had also been expanding. App developer Kinomap developed its own iPad product in 2013, using video recordings of previous marathon events to let people match their own efforts on a treadmill or exercise bike to the course. Singapore-based Paofit, later renamed to RunSocial, built its own video-based app, and released it in collaboration with the London Marathon organiser for the 2016 race, recruiting astronaut Tim Peake to promote the idea of racing remotely. He took part harnessed to a treadmill in the International Space Station, and delivered a time of just over three and a half hours that remains the world record for a marathon run in space.

Earthbound runners could do the same and have their progress overlaid on a video of the course, though they could switch to Death Valley or the Swiss Alps instead. This kind of video overlay technology made its way directly into fitness machines made by the likes of Technogym and Peloton that, in 2020, became far more popular as the lockdowns caused by the Covid pandemic forced people to isolate indoors as much as possible.

The initial spring lockdown saw the 2020 London race itself postponed to the autumn, and it only took place at all partly thanks to the combination of GPS and smartphones. Some race organisers turned to sports apps such as Strava to log progress in virtual versions of the events they could no longer hold. Instead of tracking progress live, participants would simply record their GPS-tracked run and upload the results once finished to receive a medal in the post.

On a wet day in early October, runners across the UK took their smartphones with them to track them live wherever they chose to run. They were advised not to try to do it on the traditional course to avoid too many people turning up in the same places but otherwise participants could run, or walk, anywhere in a 24-hour period. If they hit the required 26.2 miles (42.195km), they would be deemed a finisher.

The virtual race seems set to stay. In 2021, London Marathon Events supported both a full course event and its digital counterpart for what would be the largest race in its history: 80,000 runners split more or less evenly across the two. Since then, the remote race has become a staple of the event and the supporting app.

For accurate race timing on-course, the mainstay of marathon technology is the RFID tag, which sends a unique code to the timing gates along the course: placed in the London event at 5km intervals, at the halfway point just past Tower Bridge and, naturally at the start and finish.

The tags used to be chips encapsulated in hard plastic laced onto a running shoe and often expensive enough individually to need to be returned at the end of a mass event. In recent years, organisers have been switching to flexible and disposable electronic tags moulded into the tear-resistant paper bib that displays each runner’s race number. The tag inside uses the power supplied by an RF transmitter at each gate to send its unique code number to receivers under the rubber mats that every runner passes over.

The data from these gates feeds both the website and the mobile app. Users can put in the runner’s bib number not just to see their splits – the time that the runner made it through each gate in turn – but their predicted position along a line that marks out the course on a digital map if they are still in the race.

“Based on the distance and pace of a participant’s last crossed split, their icon is tracked and moved along this polyline. An estimated pace of the participant is also used in order to move their icon steadily, until they reach the next split distance,” says Gowri Prabhu, project manager at sponsor and app developer Tata Consultancy Services (TCS).

As the gates only record at 5km intervals, accurate positioning on the map depends on the runner maintaining their pace. For more accurate live positions, important for people to make sure they are in the right places to cheer on family and friends, runners armed with a smartphone can allow their copy of the app to access the built-in GPS. To maintain privacy, and in keeping with many of the general-purpose fitness apps, a runner can invite up to three people to register for the live GPS-enabled updates whether they are in the mass race or running somewhere else for the virtual event. To make sure GPS tracking works, runners will be invited to use the app on a 5km test in the week before the main race.

The app provides another way to stay connected, says Lianne Hogan, communications manager at London Marathon Events. “We introduced the Belief Booster to the digital finish gantry last year. The update for this year is that the timing mats at the halfway point will allow messages sent to participants from their friends and family.”  

The app will help synchronise messages to the display. Each runner sent a message should see it flash up once the RF receiver under the mat at the halfway point or finish line receives their code.

Away from the race itself, augmented reality (AR) and artificial intelligence (AI) now form part of the technology armoury for events like the London Marathon. The Belief Booster messages, for example, will be screened for inappropriate content jointly by AI and a team of people.

TCS has added an AR feature to the 2023 app: runners scan their bib using the smartphone camera to gain access to a video featuring veteran London Marathon participants. And for those looking to keep photographic memories of the event, runners have called on machine learning to locate pictures that show them racing. Traditionally a manually intensive process that would have workers tag each digital image with the recognisable bib numbers of the runners visible in each shot out of the many thousands taken by photographers at key points along the course, this process can now be performed by machine.

German specialist Sportograf developed software based on number recognition, like that used to track vehicle registration plates on roads, to automate the tagging process. In recent years, the company has shifted to face recognition for events such as the London Marathon as well as autumn’s Big Half. This typically delivers more photos as faces are less likely to be obscured than bibs in busy scenes.

As they set off for the event on 23 April, the important thing for both runners and spectators is to make sure they charge their device batteries to full before setting off. GPS and wireless both exact a toll on the energy budget.