proximal to distal sequencing from an authority.........

[Michael Finney]

Abstract

The motions of segments participating in striking and throwing skills are generally sequenced in
a proximal-to-distal fashion. These sequences are often described in terms of the linear velocities of the
segment endpoints, joint angular velocities or segment angular velocities. While each method of description
has its own merit, the latter is recommended since it leads to an intuitively pleasing way of explaining
segment motions. Explanations of segment motion sequences are dependent not only on a knowledge of the
joint moments driving the system of linked segments, but on the way the segments interact as functions of
their motions and orientations. The motion-dependent interaction among segments is significant and offers an
explanation of the sequencing of segment motions. As illustrated by the thigh and lower leg in kicking and
by the upper arm and forearm in overarm pitching, the forward acceleration of the proximal segment plays a
large role in causing the distal segment to lag behind. The subsequent forward acceleration of the distal
segment is largely a result of the way the proximal segment interacts with the distal segment as a function of
the proximal segment’s angular velocity. The proximal segment is subsequently slowed down largely due to
the motion-dependent effect of the distal segment on the proximal segment. Differences in the way segments
interact in striking and throwing skills can account for variations in the timing of segment actions and these
differences need to be examined before establishing general principles governing striking and throwing.


Carol Putnam
Dalhousie University
Halifax, Nova Scotia, Canada

 

[Michael Finney]

This complexity is due to the fact that each segment in a linked system influences the motions of its adjacent segments in a way that is dependent on how the segment is moving and on how the segment is oriented relative to its adjacent segments. Therefore, explaining the motions of individual segments depends on an understanding of how segments interact as functions of their motions. This paper will outline one method of quantifying the motion-dependent interaction between segments.

 

[Dariusz J.]

It is being called sequentiality of the motion. Distal parts are last in the queue. Very good read -- do you have a link to the whole article ?

Cheers

 

[Michael Finney]

The importance of describing proximal-to-distal sequences in ways that lead to their explanations is further reinforced when one appreciates that there is no logical kinematic reason that such a pattern is desirable when performers attempt to achieve high
speeds at the distal end of an extremity. When striking and throwing skills are viewed from a kinematic perspective alone, it makes more sense that they follow the principle of optimal coordination of partial momenta (Van Gheluwe and Hebbelinck, 1985; Joris et al., 1985). This principle states that to achieve maximum speed at the distal end of an open-linked system, the angular speeds of all segments should reach a maximum value at the same time. Given that the speed of the distal end of a rotating body, pivoted at its proximal end, is equal to the length of the body multiplied by the body’s angular speed, it is logical that all joints should be fully extended and all segments
should be rotating with the same angular speed at the instant maximum speed of the distal end of an extremity is desired. While this behaviour has been observed in some striking movements, such as the volley and forehand ground stroke in tennis (Deporte
et af., 1990), most throwing or striking actions typically do not approach this ideal.

 

[Michael Finney]

It is being called sequentiality of the motion. Distal parts are last in the queue. Very good read -- do you have a link to the whole article ?

Cheers

I have the paper but would rather not post the whole thing. PM me your email and I will send it over.

 

[natep]

Given that the speed of the distal end of a rotating body, pivoted at its proximal end, is equal to the length of the body multiplied by the body’s angular speed, it is logical that all joints should be fully extended and all segments
should be rotating with the same angular speed at the instant maximum speed of the distal end of an extremity is desired. While this behaviour has been observed in some striking movements, such as the volley and forehand ground stroke in tennis (Deporte
et af., 1990), most throwing or striking actions typically do not approach this ideal.

This is pretty interesting. What exactly does it mean, though?

 

[Michael Finney]

It means that in some striking movements, the big body parts and the small body parts reach max angular speed together, but in MOST throwing or striking movements the "actions typically do not approach this ideal".....

if you watch closely in this 30 frame per second video, Tiger 2000 has a little "hitch in his get along" at the hips - AKA the human body cannot physically keep up with the "ideal" and there is a slowing of the big body parts as the small body parts (and eventually club) speed up......you see it in every full swing in the video.....

 

[natep]

Cool. Thats what I was wondering, whether the ideal isn't seen because of poor technique or whether the ideal just isn't feasible due to human range of motion or strength issues, etc.

 

[SteveT]

Just imagine the sequential consequences of slinging a proximal paunch ... and the shape of the segmental velocity curves...

 

[James Marshall (Hogan1953)]

So Michael does that mean that the kinematic sequence is not optimal in absolute terms but is the best we can do as humans given our anatomical structure?

Is there anything else we can do technique-wise in order to get closer to optimal without hurting ourselves?

Thanks.

 

[Michael Finney]

Dr. Putnam said:

most throwing or striking actions typically do not approach this ideal.....

she was talking about kicking a ball and throwing a pitch.....

imagine what she would say about the body trying to keep up with a club head.....

not obtainable

see tiger 2000....dustin johnson 2012....etc etc etc...