How to execute a double-handed trill

[Waldszenen]

Hi fellas,

I'm having a bit of trouble with double-handed trills, such as those found in La Campanella and the HR2, as well as others. What's a good way to approach these things - should I keep the wrists loose and let the hand swing up and down or should I tense my wrists/arms?

[brewtality]

well it depends on what they consist of, eg octave in one hand/single note in the other or octaves in both hands. I just make sure my wrists are loose but try and not bring the hand up too high in order to maximise speed. Playing with tense muscles, hands and wrists would only serve to produce a harsh tone. Another cool variation is to play tremelos in both hands rather than repeated octaves (this is how Fiorentino played them). It adds something to the music, imo.

[quantum]

I think you're talking about alternating hand trills and tremolos. 

What I found improtant to pay attention to is how much you lift the hands.  We ususally only think of pressing down the keys, but in this action the lift is just as important as the downwards motion into the keys.  I found when practicing this technique, that uneven lift distances between LH and RH created uneven playing.  So equal lift distance in both hands is very important. 

Flexible wrists and firm fingers are also helpful.