In the September 1988 Review an article was printed which was written by
myself. The article was an extraction from a lecture given by myself to
the Judges Seminar prior to the First Main Breed Show.
A concern I had in printing the article was that due to its technical
nature, and unlike the Seminar where I could verbally explain the finer
and more complex points, the article may be difficult for many to
follow.
Indeed, this has been the case. A large number of enthusiasts have
contacted me asking for explanations on various aspects of that article.
This follow-up is an attempt by me to satisfy those enquiries.
The interest shown was most encouraging as too often one wonders if
anyone really reads some of the material we print.
In my article I used various sketches to explain various points. There
appears to have been confusion, primarily in the interpretation of these
sketches, and so I shall attempt to clarify this.
The whole basis of my article and lecture was to explain the
fundamentals of the forehand and the extract emphasised the impact of
the upper arm on movement. We start, therefore, with the basis of my
single line sketches. They are used to demonstrate the angle and the
length of the shoulderblade and the upper arm and how, as these angles
and lengths change, they affect the forereach.
This clearly shows the technical artwork that I will use. One can see a
line that travels through the centre of the shoulderblade and intersects
with the upper arm. A line then travels from this intersection through
the upper arm until it intersects with the forearm.
A point of importance here is to note the line through the upper arm
does not follow the centre of the main bone as it does in the
shoulderblade which is merely coincidental.
The reference points are the centre of the "ball and socket". The sketch Figure 2 depicts this. The importance of this is to be clearly understood and noted as it affects markedly the way in which one determines the angle of both the upper arm and shoulderblade and explains the controversy with regard to whether the upper arm should ideally be 45oor 53oThat is, if one was to run the central axis line "through" the centre of the main bone of the upper arm on the dog depicted in Figure 1, one would find that there is an angle of 45o between the upper arm and the horizontal. On the other hand, if one runs the central axis line through the centre of the "ball and socket" as depicted in Figure 1, one has an angle of 53o. This latter way of determining the angle is the correct one and as such we have an ideal of 450 for the shoulderblade and 530for the upper arm.
In Figure 3, I demonstrate these angles and lengths in single line fashion. It also shows the ideal length of the foreleg. All lengths are based on a 65cm dog.
Here we can see that to achieve the desired length of the foreleg, which is 55% of the total height at withers, the foreleg on a 65cm dog will be 36cm long. The upper arm is drawn in at 530 using the correct method of determination and as such on the 65cm dog will be 21cm long. I included a dotted line to show the upper arm as it would have been determined using the central axis through the centre of the main bone of the upper arm. That is the old method. If one was to assess this angle you would find it to be 450 to the horizontal. The shoulderblade is drawn in at 450 and one can calculate the measurement on the model as being 19cm long. Note that the upper arm is 2cm longer than the shoulderblade. There is a fundamental reason for this.
The length of the shoulderblade and upper arm is dictated by several factors.
l. The angle of each.
2. The height of the dog.
3. The intersecting points as dictated by: (a) the connection of the members,
(b) the centre of the shoulderblade should "ideally" be in line with the centre of the dog's foreleg. I recommend to any serious reader and enthusiast to get out a pencil rule and protractor and do the sketch. The points I mention will then become very logical and abundantly clear. The next sketch, Figure 4, is used to try and clearly show the way in which my various "one line" sketches work.
The sketches are used to demonstrate how a change in the length of the upper arm changes the length of the forereach. The heavy lines depict the shoulder, upper arm and foreleg in stance. The dotted line shows where the upper arm will move to when the dog is trotting. The upper arm moves forward then back, forward then back. The dotted line demonstrates this.
This shows the shaded area depicted in Figure 4 and demonstrates an ideal situation for a 65cm dog. The upper arm is set at 530 to the horizontal and is 21cm long. As the dog extends himself forward, the upper arm travels from position X to position Y and back to X and through to Z. It is a pendular effect which is effected by the angle of the upper arm and its length. We can see on this model of a 65cm dog the forward travel of the upper arm is 16cm.
Figure 6 shows what happens when the ideal is not achieved. Here we have a steep upper arm of 650 instead of the ideal 530. I also reduced its length from an ideal of 21cm to 12cm. This model demonstrates what occurs when you have a 65cm dog with a typically short, steep upper arm. The maximum forereach is always the same when the shoulderblade is set at 450. This is regardless of the angle of the upper arm. As the upper arm gets steeper the distance it can travel forward is correspondingly reduced. In this model the forward travel is dropped from an ideal as depicted in Figure 5 of 16cm to only 7cm! The last sketch, which is a repeat of the September 88 article, is put as a question once again. Those enthusiasts who are interested enough to actually get out pen and paper as I suggested may care to provide some reply! As a thought provoker, consider this: If we again use the 65cm model and give it the desired leg length of 36cm, give it the desired length and lay of upperarm and shoulderblade, and then increase the angle of the upperarm to make it steep - to say, 600 - we find that unless we shorten something, the dog becomes oversize. In fact, 2 cm oversize.
last modified: 11:25pm Sunday the 22nd of April, 2018