Jonathan Gelber, known as "Jon" or "The Fight Doctor," is an American orthopedic surgeon best known as the founder of Grappler's Heart, a not-for-profit tournament for grapplers with disabilities. According to the organization's own materials, Gelber launched the event after observing the physical and mental benefits that Brazilian jiu-jitsu offered people with disabilities, and finding that no existing platform allowed such athletes a dedicated space to compete.
The first Grappler's Heart tournament was held on April 25, 2015, at Renzo Gracie's Fight Academy in Williamsburg, Brooklyn, New York. The organization describes it as the first tournament designed for grapplers overcoming disabilities; independent coverage documents the event's existence and its continuity across multiple years while framing it more cautiously as one of the few tournaments offering adaptive grapplers a level field of competition. The third edition ran on April 23, 2017, at Vitor "Shaolin" Ribeiro's academy in Manhattan, drawing competitors such as Mike Fink and Gina Hopkins, athletes with conditions including spina bifida and dystonia. Gelber himself is the founder and organizer of the event, not a competitor with a disability.
Beyond the tournament, Gelber founded FightMedicine.net, a site focused on combat-sports injury education, and wrote a guide to preventing and treating MMA injuries. He has also contributed writing on combat sports to outlets covering the sport. He holds a blue belt in Brazilian jiu-jitsu; his significance to the sport rests on his role as an institutional pioneer for adaptive grappling rather than on personal competition results.
No public coverage of Grappler's Heart has been found after 2017, and the organization's own online materials appear to date from around that period, so the tournament may be dormant. Its historical role as an early, dedicated competitive platform for grapplers with disabilities stands regardless of its current operational status.