What steps can you take to compensate for a loss of flexibility? Start by asking yourself a question: Where am I less flexible than I used to be? It's important to know, because if you've lost flexibility in your arms but your back has remained supple, your needs are going to be different from a player with a back that won't loosen up. A simple test will tell you where to make your compensations.
TORSO TEST
Without holding a club, assume a normal stance and cross your arms over your chest. Keeping your weight on the inside of the left foot, turn your torso clockwise, rotating until your right shoulder is under your chin. If you fall well short of that mark, your back flexibility is limited; this will shorten your backswing and reduce clubhead speed.
To counter this, take a stronger grip (so you see three knuckles on the right hand) and allow your right arm to bend at the top of the swing. The strong grip encourages more active hands, while bending the arm lengthens the backswing, giving you a longer arc to create more clubhead speed.
IF NOT, THEN WHAT?
If your torso turn is adequate but you're still not approaching parallel, it's your arms and shoulders that are restricted. In that case, make the most of your shoulder turn. Rather than bending the elbow and trying to fight the club to parallel, extend it away from you on the backswing as far as possible without swaying to the outside of your left foot.
Also rotate your torso as far as possible, keeping your right arm straight. Don't worry about how high your hands are, even if they only reach shoulder height. The farther you extend your arms away from the body, the more clubhead speed your torso rotation will create.