mpassive behind a reflective visor, don’t show physical torment like other sports—soccer players running each other down like exhausted prey or the ruthless, meaty erosion of mixed martial arts. But racing a motorcycle at the professional level is brutal, agonizing work. In a single 30-minute heat, a motocross pro will burn as many calories as two marathoners and experience twice the G-forces of a fighter pilot in full vertical climb. A MotoGP rider will wrestle a 350-pound bike to the pavement hundreds of times per race at average speeds of more than 100 mph and lose a half-gallon of sweat in the process. Competitors at this level are nearly machines themselves, though of a different sort, depending on the discipline. We broke down the key specs and characteristics of two drastically different types of elite racer—the top-gun MotoGP speedster versus the airborne, dirt-slinging motocross athlete—to get a sense of that fuzzy border at the edges of human effort.