Extensor action question

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If using extensor action, should it be applied at setup or address? The book says form impact fix onward but what if you don't utilize impact fix?

This one is a continuance of the previous question. If extensor action should be applied at setup, what would the effect be if one starts with “soft” arms and then applies extensor action within the swing? I have an idea but I do not want to say what it is until I see some other opinions. Just to see if I am right or (most likely) not. I was having a problem the other day and through contemplation at a later time I was thinking that this might be it.

Thanks all

I asked this same question to Yoda and Ted last week. They don't wait until the swing starts to apply it. By applying it at impact fix, you are setting your body up in the correct impact alignments. You need to apply it at impact fix and address - whether that is adjusted adress or impact adress. In fact, you should be applying throughout the entire swing as well.