Is it possible to go from a 50-51 second 400m runner in highschool to college and really just take off with hard training and become like a 45 second runner by the time you graduate?

Yes, it is possible for a high school 400m runner with a time of 50-51 seconds to significantly improve and reach around 45 seconds by the time they graduate college. This transformation typically requires a combination of dedicated training, proper coaching, strength and conditioning, and optimal nutrition. Factors such as talent, work ethic, and injury management also play crucial roles in achieving such improvements. While it's challenging, with the right environment and commitment, many athletes have made similar leaps in performance.