Backyard Jablines is an ultrarunning race held at the Île de Loisirs de Jablines-Annet in Seine-et-Marne, east of Paris. The format is straightforward: runners have one hour to complete a 6.7 km loop, then begin the same loop again on the next hour. This continues until only one runner remains able to continue. It takes place in late March with an evening start, meaning those who endure will race through the night and into the following day.
The course is a repeated loop, making the primary challenge pacing, nutrition, brief rest periods, and maintaining composure as the field diminishes. Backyard racing can extend well beyond typical ultramarathon distances. The men’s world record is 119 loops (798 km), and the women’s record is 95 loops (637 km). France ranks fifth globally in this format, with national bests of 105 loops for men and 61 for women. Jablines is also significant for introducing the Backyard format to Île-de-France; local records stand at 32 loops for men and 27 for women.