What kind of training is there to survive 38G for 0.5s? Maybe the body can become habituated to accelerations over time or something, but what would you be training to actually do before or during those 0.5s?
Not without problems though. He "sustained a fracture of his right wrist during the runs on two separate occasions, also broke ribs, lost fillings from his teeth and bleeding into his retinas that caused temporary vision loss".
This is during short periods (of deceleration), so very different from SpinLaunch's launches.