Runners are being tracked using wireless technology, whether they are on the course or racing remotely.

The London Marathon is no stranger to technology advances. On an April morning 15 years ago, you could hear the just next to-synchronised beep of sports watches as scores of amateur runners stepped over the starting lines in Greenwich and Blackheath.

Since then, smartphones have come alongside sugary gel packs, energy drinks, and GPS-enabled watches as staples of the long-distance runner’s arsenal, as well as a near-essential item for spectators hoping to catch pictures of family and friends when they make their way down the 26.2-mile course. In the backdrop, the technology used to assist the race has advanced.

Eight years ago, the London Marathon decided to launch a smartphone app for the race. Despite having been tested on past events and deployed only for the Apple iPhone, the sheer size of the 2015 London event proved too much for the servers in charge of providing data to the app. 20,000 users downloaded the software in the two days following its release on the App Store. But another 100,000 downloaded it in the 24 hours before the marathon, and when many of them tried to find out where the runners were, the app simply would not answer.

Users were directed to the race organizer’s website for the most recent runner timings. Later years saw major increases in server capacity to accommodate expanding numbers and the addition of Android as well as Apple devices. In 2019, the organiser had 465,000 app downloads and 120,000 concurrent users at its peak.

Of course, the market for event-related software had been growing as well. In 2013, app developer Kinomap released its own iPad app that used video records of prior marathon events to allow users to match their own efforts on a treadmill or exercise bike to the course. Paofit, based in Singapore, later renamed RunSocial, developed its own video-based software and introduced it in partnership with the London Marathon organiser for the 2016 race, enlisting astronaut Tim Peake to promote the idea of competing remotely. He ran the marathon while strapped to a treadmill on the International Space Station, and his time of slightly over three and a half hours is still the world record for a marathon run in space.

Earthbound runners could do the same thing, with their progress overlayed on a video of the route, though they could choose Death Valley or the Swiss Alps instead. This type of video overlay technology found its way directly into fitness equipment created by companies like Technogym and Peloton, which became significantly more popular in 2020 as the Covid pandemic pushed people to isolate indoors as much as possible.

The initial spring lockdown forced the 2020 London race to be postponed until the autumn, and it was only possible because of the combination of GPS and smartphones. Some race organisers used sports apps like Strava to track progress in online representations of races that could no longer be held. Instead of live tracking, athletes would just tape their GPS-tracked run and transmit the results after completed to receive a medal in the mail.

On a rainy day in early October, runners all over the UK took their iPhones with them to measure their progress wherever they went. They were urged not to attempt it on the usual track in order to avoid too many people showing up in the same spots, but otherwise, participants could run or walk anywhere within a 24-hour period. They would be considered a finisher if they completed the required 26.2 miles (42.195km).

The virtual race appears to be here to stay. In 2021, London Marathon Events will support both a full course event and its digital equivalent for what will be the largest race in the city’s history, with 80,000 runners split roughly evenly between the two. Since then, the remote race has been a fixture of both the event and the accompanying app.

The RFID tag, which sends a unique code to the timing gates throughout the course, is the mainstay of marathon technology for accurate race timing on-course: situated in the London event at 5km intervals, at the halfway point just below Tower Bridge, and, of course, at the start and finish.

The tags used to be hard plastic chips that were tied into a running shoe and were typically expensive enough individually that they had to be returned at the end of a large race. In recent years, race organisers have shifted to flexible, disposable electronic tags that are moulded into the tear-resistant paper bib that shows each runner’s race number. The tag inside uses the power provided by an RF transmitter at every entrance to deliver its unique code number to receivers hidden beneath the rubber mats that each runner passes over.

The information from these gates is used to power both the website and the mobile app. Users can enter the runner’s bib number to see not only their splits – the time the runner took to pass through each gate in turn – but also their expected position along a line which marks out their route on a digital map whether they are still in the race.

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

Because the gates only keep track at 5km intervals, proper mapping is dependent on the runner keeping their pace. Runners equipped with a smartphone can authorise their copy of the app to use the built-in GPS for more exact live positions, which is vital for people to ensure they are in the proper areas to cheer on family and friends. To protect anonymity, and in line with many general-purpose fitness programmes, a runner can invite up to three friends to register for the live GPS-enabled updates, whether they are running in the mass race or elsewhere for the virtual event. Runners will be invited to use the app on a 5km test run the week before the main race to ensure GPS tracking works properly.

According to Lianne Hogan, communications manager at London Marathon Events, the app provides another option to stay engaged. “Last year, we added the Belief Booster to the digital finish gantry. This year, the timing mats at the halfway mark will let participants to receive messages from their friends and family.”  

The programme will assist in synchronising messages to the display. Once the RF receiver under the ground at the halfway point or start line receives their code, each runner should see their message flash up.

Aside from the race, augmented reality (AR) and the use of AI are now part of the technology arsenal for events such as the London Marathon. For example, AI and a team of humans will check Belief Booster communications for inappropriate content.

TCS has added an AR element to the 2023 app, allowing runners to scan their bib with their smartphone camera to see a film featuring seasoned London Marathon participants. Runners have used machine learning to find photos of themselves racing in order to preserve photographic recollections of the experience. Previously a labor-intensive process in which people would tag each graphic with the recognisable bib number of the runners seen in each shot taken by photographers at critical places along the course, this method can now be handled by machine.

To automate the tagging procedure, German specialist Sportograf developed software based on number recognition, similar to that used to track automobile registration plates on roads. In recent years, the firm has turned to facial recognition for events like the London Marathon and the Big Half in the autumn. Faces are less likely to be concealed than bibs in hectic scenarios, so this usually results in more images.

The crucial thing for both runners and spectators as they set off for the event on April 23 is to make sure their device batteries are fully charged before setting off. GPS and WiFi both drain the energy budget.