Paddy O'Leary

Pro Ultra Runner

Paddy O’Leary is a professional trail and ultra runner, cancer biologist, community leader, film maker, and former international lacrosse player living in San Francisco, California.

Originally from Ireland, Paddy immersed himself in trail running as a sport after his move to San Francisco for a job in cancer research. Soon enough he was competing across the international circuit, and has had success in races both on the trails and the roads, as short as a 5K all the way to 100 miles. He’s had notable results in races with podiums and top-10 results at the Canyons 100K, Lavaredo Ultra Trail, Ultra Trail Cape Town, and Mexico by UTMB. In 2023, he took a coveted first place finish at the iconic Dipsea Race.

He discovered Precision Fuel & Hydration at the team’s impressive showing at the 2024 Western States 100 miler, and connected with them through his coach and PF&H athlete, Mario Fraioli. After working with PF&H Sports Scientist Sam for guidance through some impressive results across the rest of the 2024 season, Paddy formally joined the team in 2025.

Balancing elite trail running with his career in medical research, Paddy is a passionate advocate for better communication, outreach and storytelling across the sciences and his sport, whether that be about his work as a molecular biologist or advocating for protection of our wild spaces.