The Norwegian runner named Warholm Karsten just broke the world record in the 400 m hurdles 45.94 —- sub 46.
I had to look it up to know that my hero Harry Hillman won the 1904 version of the same race in 55 seconds flat.
Thats about 16 percent in 117 years improved. Or its moved less than a second every decade.

The other detail this made me think of is that Don Burnham told me that Harry Hillman brought Gunder Hagg to Hanover to train, and it was likely the first time that fartlek was practiced here, speed play. 

ok, since his name is Warholm I will mention that Harry Hillman and Lawson Robertson were part of an elite track team that was related to training young men to become soldiers, sort of like the modern ROTC. His Brooklyn unit was the nucleus of the US Track team that won all the medals at the 1904 St. Louis Olympics.