Transition From 3 To 4th Finger

Dear Alan, my 4th and 5th fingers keep being weak and "entangled". Every time I play a passage that requires to go rapidly through the 3rd to the 4th finger, the latter barely presses the key. Can you recommend and exercise to consolidate a smooth transition. Regards,

Whew, what a question! I can't really reprint my whole book here - I think I'm going to have to be content to simply recommend you go read about skeletality and why the perception that our 4th & 5th are weaker than the others is an illusion. Let us know how you do! AFF