In what has been an annual tradition for years, the 2025 Massachusetts ultrarunning season will kick off with the the G.A.C. Fat Ass 50K. Gil’s Athletic Club will play host to the event for the 25th time at 8 a.m. Saturday, Jan. 4, at Bradley Palmer State Park in Topsfield.

The course will be the same as the past few years, consisting of a rolling loop on singletrack and doubletrack trails and about a mile of pavement. The start/finish will again be near the ranger station at the western end of the park near the Asbury Street entrance. Runners may complete however many laps they want to, up to five for a 50K finish.

Participation in the event is free, but runners are encouraged to bring a food or drink item to contribute to the aid station.

For additional details, check out the GAC website.