They started using clap blades-frames back in the 1900's. In the 1980's marathon skaters tried to use the clap skate in competitions. But it's use was prohibited by officials due to the increased risk of physical harm. It wasn't until the 1990's that they really caught on.
Once they did catch on, lots of world records were broken. In general, a 6% decrease in times was seen when using clap blades-frames. In the 90's some skaters said the clap skate should be illegal, and should be banned. But, clap blades were banned for short track speed skating.
Research in 2000 showed the speed gain from using the clap blade-frame is not because the calf muscle is more fully used. But because the point of rotation is moved from the tip of the blade, to the hinge, which helps the transfer of power to the ice.