The widespread adoption of consumer-grade wearable devices has transformed endurance sports training from intuition-based to data-driven practices. Data has become a key element in training and performance analysis for competitive athletes first, but also for general users. Despite the availability of hardware, a silo problem persists in the software environment: each manufacturer such as Garmin, Coros, Polar, or Suunto, locks users into its ecosystem and confines data into proprietary structures that prohibit users from changing hardware or use multiple devices without losing a global view of their training history. This interoperability problem highlights the need for a neutral platform that can centralize and normalize this heterogeneous data.