I think as bwl_13 says that the technique is developed over years, and that it is not a matter of strength either. I also think it depends on what piano you practice on, electric pianos or keyboards are often very light and you don't have the feeling of weight.
For years I have tried those by Hanon, Schmitt, Philipp, Beringer, the Czerny Op. 299 School of Velocity études, and Op. 740. Then the Chopin études. I am 59 years old and I started studying at 5, and I still love practicing the piano.