One of the most common questions we get asked by golf beginners is "do I have good posture" and "am I flexing my knees enough."
The answer where 'good knee flex' is concerned is a tricky one, simply because it all depends on the golfer's height, body type, club and distance stood from the ball. There is therefore specific amount of knee flex for a 7-iron, especially for a guy who is 6 foot tall because he may have a 29 inch inside leg or a 34 inch inside leg.
It may sound silly or very simple, but the best way to obtain correct knee flex in the swing is to experiment. Here are some helpful pointers and things to avoid...
The more knee flex you have, probably the more rounded and shallow the golf swing will become.
So if you're hitting hooks, or if you're hitting the ground before the ball, or thinning the ball because you're coming in too much in-to-out, I'd encourage you to straighten the legs a little bit. This will steepen your golf swing, change your impact and change the attack angle of your golf club.
With the research we've been doing with the guys at Gears Golf lately, we're finding the majority of the joint angles on the way back that the right leg is straightening - it doesn't lock - to the tune of somewhere between about 3 and 6 degrees.
So if someone is starting at 20 degrees at the top of their backswing, we may see that the right knee is now only between 14 and 17 degrees - so there is a straightening, but it doesn't straighten.
I am yet to see any evidence from a top player who actually locks - i.e. completely straightens - the right knee in the backswing.
On the way down, we are obviously going to see the reverse happen with the left knee straightening, whereas the right knee doesn't fully lock on the way back, the left knee will straighten and lock on the way through at some point.
You don't want to have the left knee flexing any more, and you definitely don't want the right knee to flex any more in the downswing as all that is going to do is shallow the swing out massively, and causing big pushes and big hooks due to rotation or timing of the clubface closing through impact.
There have been a lot of good 'leggy' players in the past, such as Jack Nicklaus and Colin Montgomerie. That's why you can't really say you have to do that with the left leg and right leg.
I think today we are seeing a lot more guys working on better ways to control their ball flight, and whether their legs are assisting or not helping that.
Your end goal where knee flex is concerned is find a position that is comfortable, balances your weight properly and enables the hips to move freely back and through your swing.
Try to think about setting up with your knees over the balls of your feet and your backside just outside the heels. Your weight should be balanced in the centre of your feet.
During the backswing, try to maintain good flex in your right (back) knee to act as a brace for your hip turn.
Good luck, and if you need any more helpful pointers, tweet me here.