Should all the body parts reach the top of backswing at the same time?

Should all the body parts reach the top of backswing at the same time?  For the best way to use your muscles to generate the most power, the answer is NO.  Remember the Kinematic Sequence; the curves of the turning speed of the hips and shoulders and the swinging speed of the lead arm and club shaft, graphed throughout the swing.  Our standard pro example is shown below.

 

The Kinematic Sequence

Arguably the two main parts of the sequence the transition at top of backswing and the peaking order in the downswing.  However let’s focus on the transition phase in this article to answer the question; “Should all the body parts reach the top of the backswing at the same time, and in addition, start the downswing at the same time”.  The answer is, for the most power, no. 

The Kinematic Sequence of the Transition Phase

For the most efficient method of generating power from the muscles at each joint during the transition, the body should turn around in a sequential manner, starting with the larger body parts followed by the smaller body parts.  The pelvis should turn first, then the ribcage, arm and finally the club.

This method allows the muscles at each joint to effectively use the “stretch-shorten cycle” to produce a higher force in each muscle and hence more power.  Think about jumping, would you squat down, hold the squat for a few seconds and then jump, or would you squat down and immediately jump up?  The latter method has been proven to produce higher jumps because initially the muscles are loaded eccentrically while squatting down.  This allows more force to be generated for at least two reasons:

1.     Eccentric contraction builds a higher force in the muscle than either isometric or concentric contraction, and if the muscle starts out at a higher force it can generate more force during the concentric phase.  Eccentric means the muscle is lengthening while it is contracting, isometric means the muscle is contracting but not moving, and concentric means the muscle is shortening while contracting.  The concentric phase is the one that generally moves us in the direction we want to go.

2.     Elastic energy in the connective tissue can be stored and then quickly returned if the turnaround is relatively fast; adding to the force in the muscle.

Now relate this principle to the transition phase from backswing to downswing in golf.  I will use the hips and shoulders for the example.  Near the top of backswing the legs and hips are pulling to change direction into the downswing but the shoulders are still turning in the backswing, this causes and eccentric loading of the torso muscles, loading them to a higher level, so when the shoulders finally turn around they can fire much stronger than if they had turned around at the same time as the hips.

How can we prove that this is generally the case in top golfers?  We simply look at the Kinematic Sequence curves using the TPI 3D data.  If the red, green, blue and brown curves cross the zero line at different times then muscle loading is occurring and the body segments are not starting down at the same time.  From the TPI database of male tour pros for the driver, the average time of the transition phase is about 55 milliseconds.  If all the body segments turned at the same time this would be zero, and it is not.

On the other hand, do some top golfers turn all body parts around at almost the same time?  The low end of our TPI 3D database range for the time of the transition phase is 17 milliseconds.  This is a pretty short time, less than 2 hundredths of a second.  So, can it still be a reasonable efficient and powerful swing with such as short transition phase?  Yes, I think so, because if you have mostly “fast twitch” muscle fibers then you fire faster than those with “slow twitch” muscle fibers.  So I expect that golfers with fast twitch fibers will have faster transition phases than those with slow twitch fibers, and so they should, because each needs to use their particular type of muscles in the best way for themselves.  I haven’t proven this yet but it makes intuitive sense.