In a fascinating discussion about fitness and body transformation, neuroscientist Dr. Andrew Huberman highlighted the remarkable physical changes that can occur when endurance athletes pivot to resistance training.
The conversation, which took place during an appearance on the Flagrant podcast, touched on the case of retired Stanford marathon runner Ryan Hall, whose physique underwent a dramatic metamorphosis once he transitioned from running to lifting weights.
Dr. Huberman explained that Hall, who still holds the American record for the fastest U.S. marathon, was characteristically lean during his competitive running career—”like a stick,” as Huberman described it.
However, after retiring from professional running and incorporating heavy lifting into his routine, particularly deadlifts and squats, Hall’s body composition changed dramatically.
Huberman said: “He was like a stick. Finished running, got out, started lifting weights, he’s a beast. Looks like something out of a Marvel movie. Really, mostly because he’s just eating and dead lifting and squatting now. He still runs a little bit, but he’s not running gazillion miles a week.”
This transformation exemplifies an important principle in exercise physiology: the body adapts specifically to the demands placed upon it. While marathon running promotes a lean, efficient physique optimized for endurance, resistance training stimulates muscle hypertrophy and strength development.
When Hall shifted his focus from logging “gazillion miles a week” to heavy compound lifts while maintaining adequate nutrition, his body responded by building significant muscle mass.
Hall’s case is particularly striking because it demonstrates that even athletes who have spent years developing one specific athletic adaptation can successfully pivot and build an entirely different physique.
Dr. Huberman emphasized that such transformations aren’t exclusive to elite athletes. He outlined a practical fitness framework for the general population: three days per week of resistance training, including leg work, combined with three days of cardiovascular exercise—one long steady-state session, one sprint interval session, and one enjoyable activity like basketball or Pilates. This balanced approach, he suggested, supports both aesthetic goals and long-term health.
