A single innovation in skate design caused the world speed skating records in all the categories to be broken in the 1998 Olympics.
One of the most controversial changes in the recent history of speed skating involves use of clapskates, also known as slapskates. The blade on clapskates is attached by a hinge to the front of the boot. As a result, the blade will detach from the heel of the boot as the skater pushes with her calf muscles through the end of a stroke. Used by skaters in long track races, clapskates allow skaters to keep their blades on the ice slightly longer than with traditional skates, giving them more power and speed. While clapskates had been around for over a hundred years, it wasn't until inventors and engineers started working with biomechanics researchers that the technology was really developed for professional skaters. After 1996 when the Dutch women's skaters demonstrated how effective the skates could be, it wasn't long before all serious competitors were using them.
Pictures and descriptions of long track speedskates demonstrate the difference between traditional and clapskates.
To read more, here is an article describing clapskates and the impact they have had on the sport.