40 yard dash is the NFL's standard, and it typically is not that accurate as the clock doesn't start until the runner moves (timers have to pay attention), where in a track & field race the runners don't move until a starter's gun goes off (and the races are 100m or longer outdoors, 60m indoors).

I never ran a timed sprint race that I can recall, and even in my younger days I'd look pathetic against anyone who had any sprinting ability I used to run distance races in high school and college, and was known for having a good finishing kick, but all the races were 1-mile and longer (no 1500m back in those days).