Hasn't set me back one bit. The only thing that sets me back is delayed onset muscle syndrome (DOMS) which is the normal muscle pain you feel a day or two after a good workout. As long as I stay warm and stretch well before and during play, I'm fine.
If you are like me and tend to get a little bulky through upper body, just take a little extra hip turn to keep everything on plane. Upper body muscle is usually very relaxed and nimble during a golf swing anyway.
I'm more flexible now than when I was in my 30's/40's.
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Bagger
1-H "Because of questions of all kinds, reams of additional detail must be made available - but separately, and probably endlessly." Homer Kelly
Hey Bagger, thanks a lot for the props, now back to the gym!
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"In my experience, if you stay with the essentials you WILL build a repeatable swing undoubtedly. If you can master the Imperatives you have a champion" (Vikram).
The reason you can't sustain the lag is because you are so eager to make the club move fast (a reaction to the intent of "hitting it far"). So on a full shot you throw it away too early, which doesn't happen for your short chip. (bts)