Articles

# The Linear Kinematic Sequence

Mon Mar 17, 2014 by Phil Cheetham

It is known that there is an efficient sequence of motion in a skilled golf swing called the Kinematic Sequence.  It describes the proximal-to-distal sequencing of the rotation speeds of the body segments. Each body segment; pelvis, ribcage and arm sequentially accelerates and decelerates before impact, starting from the inner large body segments; the pelvis and ribcage, then progressing to the smaller outer segments; the arms, hands and club.  Each successive segment peaks faster and later than the previous segment.  This action causes the club to accelerate rapidly and reach its highest speed at impact.  Figure 1 shows the graph of the rotational Kinematic Sequence of a world class golfer and includes images of his position at each peak speed point in the downswing.

It is also known that the golf swing is not only rotational; it has a linear component of motion as well.  Therefore it would make sense that there is also a linear kinematic sequence during the downswing, and in fact there is.  Figure 2 shows the linear Kinematic Sequence graph of a world class golfer.  It shows the linear speed of his lead hip, lead shoulder, mid-hands and club head.

Look in the shaded gray area of Figure 2 and notice how, during the downswing, the lead hip accelerates (goes up) and reaches its peak speed first, then decelerates (goes down), followed by the lead shoulder, the mid-hands and finally the club.  Notice that these accelerations and decelerations are all before impact and that the only segment that doesn’t decelerate prior to impact is the club head.  As we would expect, the club head accelerates during the downswing and reaches max speed at impact.  Notice that each successive peak speed occurs later in the downswing than the previous one and is faster than the previous one.

In fact, it is not as important what the speeds of the joints are at impact but what their maximum speeds are earlier in the downswing.  We expect their speeds at impact to be lower because of the deceleration phase of each joint as it passes energy to the next segment - each joint is slowed down by the interaction force of the next segment accelerating against it.  Take for example the mid-hands curve.  You see that its highest speed is 22.6 mph and its speed at impact is 19 mph.  For the mid-hands curve, the deceleration is related to the explosiveness of the release.  The faster the release of the wrists the more the deceleration and the slower the hands will be at impact.  It is a nice example of the action-reaction law of motion; the force of the club releasing causes and opposite force on the hands causing the lead arm to slow down.  This means that measuring hand speed at impact may be misleading. It’s better to know what the peak hand speed was earlier in the downswing.  From our research at TPI we have compiled a tour pro database and from this database, we have found that the average peak mid-hands speed in the downswing is 22.0 mph and the average mid-hands speed at impact is 17.6 mph.

The 3D Guy

• Gracias por esta información Y la biomecánica que es lo que va marcar cada vez más el swing

• Na ja so richtig neu ist das nicht, aber immer daran erinnert zu werden.

• Very interesting. Thank you.

• Thanks for the information Phil. This goes a long way to unlocking "casting". DL

• Note on the second diagram. How the Lead shoulder and mid-hands speed lines are not a smooth curve into deceleration. They appear to be interrupted by the weight of the arms and club respectively. As they move out of a lag position accelerating into the point of impact. This is why It is so important to hit through the ball. That way you maintain as much of the speed in your hands for the club to lever around. Move or maintain just 3 mph more in hand speed through the ball and the club head will be traveling more than 18 mph faster at impact. Regardless of what swing style you have.

• Phil, do you see a different speed averages for one plane and two plane swings?

• Great job Phil In the linear swing the hips job is to swivel to accomidate the levers which produce most of the power in this swing, so yes there is rotation its just not the main force.

• How can you swing a golf club and not be rotary? This is looking at the linear values of specific body parts during a rotational golf swing.

• How does that compare to the Rotary Swing ?

• Rotational is secondary to the linear component (per Mike Austin)