I am going to go way out on a limb here and assume that you, like most runners, are not a world class runner and therefore will never come close to challenging a world, Olympic, national, regional, or similar record. In the world of running, runners instead celebrate their personal records or PRs. It does not matter how fast one ran a race, what matters is how fast the runner ran for a specific distance relative to that runner’s past performances. Since most runners compete in races of various distances, most runners will accumulate their own best finish time for each distance. Thus, the title PR for that distance.