The correct ‘sequencing’ of the
motion of the arms and body is the
key to a consistent swing

Without doubt, the failure to coordinate the movement of the hands/arms with the rotation of the body accounts for much of the inconsistency suffered by the club player.
Whether the arms out-run the turning of the torso, or ‘lag’ behind, or simply move in a jerky and disjointed fashion, this loss of ‘connection’ between the arms and the body inevitably leads to a breakdown of the overall swinging motion. There is no sense of togetherness, of a gradual gathering of pace, and the motion lacks the rhythm that we associate with a repeating action.
How do you correct this and work towards the goal of having the hands, arms and body working in an orderly, synchronised fashion? Well, first, you have to be aware of the basic structure of a good set-up position – the starting point for every repeating swing. After that, you need to be aware of what we refer to as the ‘sequencing’ of a good motion, where the movement of the arms compliments that of the body, with a gearing effect that maximises the benefits of centrifugal force and acceleration all the way up to and through impact.
Take a look at this close-up focus on the arms and torso (below). From the set-up, the first movement away from the ball sees the triangle of the arms and shoulders control the initial movement of the club. What you don’t want is the upper body turning too quickly; the ideal scenario is one where the arms initiate this opening move, to create a little momentum in the clubhead, whereupon the turning motion of the upper body picks up on the action and generates the coil to the top of the backswing. Within this, the wrists can be seen to hinge to set the club up on the desired plane.
If you rehearse in slow motion this early sequence of moves, the emphasis on the arms and hands initiating the movement of the club for the first few feet of the swing, you will find that good rotary motion of the upper body then completes a compact backswing. Here I’m using a 6-iron, and this three-quarter type arm-swing, combined with a full shoulder turn, is ideal.