As tens of thousands of runners prepare to pound the streets of London this Sunday for the 46th TCS London Marathon, the race they are running looks very different from the one that launched in 1981.
Beyond the GPS watches visible on the start line, an entire ecosystem of smart technology now underpins every aspect of a marathon – from how athletes train their hearts to how spectators track their loved ones through the streets of the capital.
With participation in major marathons at an all-time high and demand for places far outstripping supply, organisers and innovators alike are turning to technology not just to enhance the experience, but to redefine what is possible in endurance sport.
Here are five of my favourite technology innovations.
Digital twin heart
When Boston Marathon champion and two-time Olympic marathoner Des Linden agreed to partner with Tata Consultancy Services (TCS), the result was something that would not have seemed possible a decade ago: the world’s first digital twin of a professional marathon runner’s heart.
The process began with Linden undergoing an MRI scan. That anatomical data was then combined with her training data and historical physiological datasets to construct a real-time, virtual replica of her cardiac system – one capable of modelling how her heart responds under race conditions. The digital twin of Linden’s heart was unveiled at the 2023 TCS New York City Marathon, where it provided vital cardiac parameters including stroke volume, cardiac output, left ventricle ejection time, diastolic filling time, and blood pressure – all derived from simulation rather than invasive monitoring.
The significance goes well beyond elite sport. Using AI-powered modelling and machine learning, the digital heart can simulate thousands of training and race-day scenarios – varying weather, sleep, course gradient, and effort level – allowing coaches to optimise preparation without the athlete running a single extra mile. It can also flag early warning signs: irregular heart rhythms, signs of fatigue, or cardiovascular stress that might otherwise go undetected until it is too late.
TCS has since expanded the initiative beyond Linden, creating digital twin hearts for a broader group of runners ranging from competitive athletes to recreational participants.
Face recognition photography
Finding your race photos used to mean scrolling through thousands of images and hoping someone had captured you mid-stride. Sportograf, a German sports photography company, has used machine learning to make that a problem of the past.
The company originally developed software based on bib number recognition – using optical character recognition (OCR) algorithms similar to those used in automated number plate recognition (ANPR) systems on roads – to automatically tag athletes across tens of thousands of race images. As the technology has matured, Sportograf has shifted towards biometric face recognition for major events including the London Marathon and the Big Half.
Runners upload a single selfie before or after the race; the system then extracts facial vector data and cross-references them against the company’s full image library using probability matching. The process increases the number of accurate photo matches by up to 120% compared to bib-number recognition alone, particularly useful for images captured from the side or where bibs are obscured.
Sportograf now photographs over 10 million athletes per year and processes around 30 million images annually. All facial vector data is processed within the EU under GDPR, and selfies are not stored beyond the point of search.
Smart Medal
The Smart Medal initiative, first introduced at the TCS Amsterdam Marathon in 2019, was designed to extend that moment a runner crosses the finish line and give every finisher a richer, shareable record of their achievement.
The original system embedded NFC (Near Field Communication) chips inside physical finisher medals. Runners held their medal against a smartphone to trigger a personalised digital experience – a so-called ‘Running Story’ that combined race timing data, split information, and photographs from the course into a single shareable package.
When TCS invested in the project, its engineering team developed an image recognition alternative that eliminated the need for expensive NFC hardware entirely. Using a smartphone camera, the app now identifies the specific medal by visual pattern recognition and retrieves the corresponding runner data from the Cloud. The result is a scalable solution that can be deployed at far more events globally, without requiring any embedded electronics in the medal itself. Runners can also collect and store all their past medals digitally, building a portfolio of their race history within the app.
Robot-sprayed LightSpray shoes
While much of the innovation in marathon footwear has focused on what goes under the foot, Swiss brand On Running has taken a different approach – reinventing how the upper of a running shoe is made entirely.
On’s LightSpray technology uses a pre-programmed robotic arm to spray 1.5 kilometres of a specially formulated thermoplastic polyurethane (TPU) filament directly onto the midsole of the shoe in a single continuous process. The robot follows a precise path, layering the filament to create a seamless, sock-like upper with no stitching, no gluing, and no cutting – eliminating hundreds of individual manufacturing steps. The entire process takes approximately three minutes. The resulting upper weighs just 30 grams and is fused to the carbon-fibre and foam midsole using heat rather than adhesive.
The performance credentials are real. Kenyan runner Hellen Obiri wore a prototype version of the LightSpray Cloudboom Strike to win the 2024 Boston Marathon, and in 2025 she took almost three minutes off the New York City Marathon course record, finishing in 2:19:51. The shoe was named one of Time Magazine’s 200 Best Inventions of 2024.
Beyond performance, the manufacturing process delivers a significant sustainability benefit: because the filament is sprayed only where it is needed, there is virtually no wasted material. On reports that the LightSpray upper produces 75% fewer carbon emissions than a conventionally manufactured running shoe upper. If defects occur during spraying, the TPU filament can be reheated, removed, and reapplied – making it recyclable within the production process itself.
Ray-Ban Meta smart glasses
Perhaps our favourite use of technology is from Clarke Reynolds – a blind Braille artist and children’s author from Portsmouth known professionally as Mr Dot – who made history at the Brighton Marathon on 12th April 2026.
Reynolds, who has retinitis pigmentosa, an inherited degenerative condition affecting the retinal photoreceptors, retains only around 5% of his vision. He previously completed the 2023 London Marathon tethered to a guide runner in the traditional fashion. This year, he dispensed with the physical guide entirely – replacing that human tether with a global network of remote volunteers connected through technology.
The setup combined Ray-Ban Meta Wayfarer smart glasses – which feature an integrated wide-angle camera, open-ear speakers, and a microphone – with the Be My Eyes app, a platform that connects blind and low-vision users with sighted volunteers via live video. By saying “Hey Meta, come be my eyes,” Reynolds was instantly connected to a pre-selected volunteer anywhere in the world who could see through his glasses in real time and guide him around obstacles, kerbs, parked cars, and other hazards. Volunteers rotated every 30 minutes throughout the race, with approximately 150 individuals from around the world supporting him across both his training runs and race day itself.
Reynolds completed the 26.2-mile course in just under six hours and 20 minutes, raising funds for Fight for Sight UK, and became the first blind person in the world to complete a full marathon using smart glasses connected to a live assistance app.
Summary
As the London Marathon enters its fifth decade this Sunday, technology is no longer a footnote to the event. The question for the sport going forward is not whether technology will continue to reshape the marathon, but how quickly those changes will arrive.
