Lyoto Machida
Former UFC Light Heavyweight Champion and Karateka, who experienced significant improvements in his breathing and stamina using the O2 Trainer, especially after recovering from COVID-19.
Videos Mentioning Lyoto Machida

UFC Hall of Famer Bas Rutten on Self-Defense, Savage Fight Stories, Breathing Techniques, and More
Tim Ferriss
Former UFC Light Heavyweight Champion and Karateka, who experienced significant improvements in his breathing and stamina using the O2 Trainer, especially after recovering from COVID-19.

John Clarke: The Art of Fighting and the Pursuit of Excellence | Lex Fridman Podcast #143
Lex Fridman
MMA fighter known for his karate-style distance management and beautiful foot sweeps, highlighted as a master manipulator of distance.

Georges St-Pierre: The Science of Fighting | Lex Fridman Podcast #179
Lex Fridman
Mentioned as having the second-best reaction time in the UFC roster at the time, according to GSP's frame-by-frame analysis friend.

Ryan Hall: Martial Arts and the Philosophy of Violence, Power, and Grace | Lex Fridman Podcast #125
Lex Fridman
A Brazilian mixed martial artist, mentioned as an example of a fighter BJ Penn faced, highlighting the diversity and challenge of his opposition.