Lead elbow flex refers to the bend in your lead (front) elbow during the golf swing. More flex usually means more inconsistency—causing fat or thin shots. Better players maintain a straighter lead arm by pushing their arms outward throughout the swing, rather than pulling them in toward the body.
The key to making solid contact every time comes down to training a good backswing

There's hardly a better feeling in the world than hitting a golf ball perfectly. The sound and feeling of making solid contact is unmatched.
However, for some golfers, that feeling hardly ever happens - in many cases due to poor fundamentals within the backswing.
Quite often, the culprit of consistently mishitting the ball occurs in part from the elbows bending too much in the backswing. This can lead to a multitude of problems, including hindering the golfer's turn and leading the club to hit the ground before the ball in the downswing.
Of course, there are many components that go into making solid contact a constant element in your game. A good starting point to help this common issue is to reduce the amount of elbow bend in the backswing.
When training a good backswing, it boils down to feeling like your arms are much less bent on both the way back and way through, all the way into your finish position.

In the video below, GOLFTEC's Patrick Nuber explains how to do this in detail, and gives a simple drill to help train a good backswing by maintaining straighter arms in the backswing and downswing.
With a little practice, your backswing will be much improved and you'll start achieving that one-of-a-kind feeling more than you ever have!
