**Paris at 50: Your Sneakers Are Now Smart**

The Paris Marathon celebrates its 50th race this Sunday, but the runners will look very different from those in 1976. Today, technology is the invisible coach for thousands of participants. Wrist monitors and phone apps now track every heartbeat and step. Runners use this real-time data to manage their energy and avoid exhaustion. This shift turns the historic event into a live experiment in human performance. The course remains a classic tour of Paris, from the Champs-Élysées to the Arc de Triomphe. Yet for the modern athlete, the iconic scenery shares attention with glowing screens reporting their personal stats. As Caitlin Brown reports, the marathon’s golden anniversary is not just a celebration of distance, but of data.