The story of the organization began in October 2015 with the founding of the Sport Ouest Organisation agency by Julien Gaborieau. Created to take over the management of the Nantes Marathon, the agency immediately achieved a historic milestone by launching the half-marathon and the nighttime Elephant Run, causing the event to leap from 4,200 to over 13,600 runners in its very first edition.

Building on this success, the agency quickly diversified its formats and deployed its technical expertise. In 2017, it provided its operational engineering services to Puy du Fou to bring La Foulée des Géants (The Giants' Run) to life, before creating La Duchesse (The Duchess) the following year at the heart of the Château des Ducs de Bretagne (Castle of the Dukes of Brittany). These events met with immediate popular success, selling out months in advance and becoming unmissable events in the region.

 

In July 2022, Sport Ouest Organisation reached a major strategic turning point by joining the OC Sport group. This alliance solidified the organization's leadership in Western France and enabled it to launch groundbreaking innovations. This was the case in 2025 at the Nantes Marathon, where the teams designed "La Traversée SurpreNantes" (The Surprising Nantes Crossing), a unique 324-meter floating footbridge over the Erdre River, hailed as a world first and awarded twice for its logistical audacity.

Today, leveraging this comprehensive expertise, OC Sport's Nantes branch has established itself as a leading name in endurance sports and large-scale mass gatherings. Building on the massive success of the Nantes Marathon, the launch in 2024 of the Amarris Côte d'Amour International Marathon and the recent revival of the legendary 24 Hours Cycling race on the Le Mans circuit, the organization manages a portfolio of events bringing together nearly 60,000 participants around a unique and rigorously eco-designed sporting experience.