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has chosen specific heights
received many queries on how and why they chose
their four jump heights UK Agilty has chosen to answer these questions in an open article to
all agility people via the agility media.
To address the
speculation about UK Agility copying other international organisations (mainly USDAA) we would
like to state that the only jump height we share is the 12" division. We do not know of any
other organisation in the world that offers the same jump heights as us.
First, keeping in
mind that one of UK Agilityís major aims is to cater for as many competitors and dogs as
possible, we chose the following height divisions:-
inches and below
inches and below
inches and below
UK Agility does,
however, give the handler the choice of jumping the dog higher than the jump height their dog
is eligible for.
Second, it was
important to us that we did not force equipment suppliers and the private individual to have to
revamp their equipment to meet new jump heights. Therefore, when creating the new height
divisions, we kept in mind the current available equipment specifications. One manufacturer has
told us that cost to change their hire equipment to different jump heights such as USDAA would
be in the region of £8,500 and the cost to clubs around £12 per jump.
Why pick these heights?
One of the most discriminated groups of dogs in British agility has been the smaller
breeds. UK Agility wanted to create a more evenly distributed group of smaller dogs to
increase the level of competition and fun.
Our 12" jump
height was designed with the smaller mini dogs in mind (toys, etc.) We wanted to create a
division that would enable dogs that size, a category which would allow them to compete
under conditions suited for them so that they may show their true abilities, thus
increasing the standard and diversity of breeds at this height in the UK.
The idea of
the 15" class is to again encourage and increase the standard of dog at this height.
While we were in the planning stages, gathering data and observing results of agility
shows, we also noticed that many Midi classes were small in number and were perhaps, a
slightly lower level than the standard dogs.
observed a trend, of Border Collies, measuring under 17", entering these classes. By
removing the 16-17" dogs from this division, we felt that we would prevent the Border
Collie from dominating this division and again encourage people to stick with their
original breeds. We were also hoping to establish a division that would give dogs
measuring 15-16" - as so many of the shelties, poodles and smaller mixed breeds do - a
fairer but also more competitive competing environment.
division was developed for a couple of reasons. One was to split the collies into 2
groups of larger and smaller. The other reason was to encourage other breeds and mixed
breeds that struggle to jump 30" due to height and structure, measuring 20 inches and
under, into the sport. The reason for the 24" jump height for this division of dog was
that we felt that the other jump heights such as 20 inches, was too low for a 20" dog to
jump, while a 26" jump height was too high for 16" dogs to jump. Once again, there was
the fact that other jump heights would require equipment modification in Britain.
The 30" height
division was maintained firstly due to the fact that it is the essence of British
Agility. Although, more importantly, 30" was kept because research as well as our own
observation has shown that jumping higher is not only safer, but influences a better jump
style and form.
Unfortunately, not much effort has been put into the proper research on agility dogs and
jumping. In addition, some of the research done is not as scientific as would be liked.
One piece of research coming from the Netherlands studied how jump height affects
injuries in dogs. It concluded that speed, not height, is more likely to cause injury. It
has also been concluded that the lower a dog jumps, the faster the dog will go. The
faster the dog travels, the more impact is caused when turning and hitting the other
equipment. As said though, itís been suggested that this is not as scientific as it could
Amanda Pigg's Jag
Wanting to get the best information available, we spoke to a Professor of Physics at the
University of Washington, Prof. John G. Cramer who further explained the relationship between
an objectís impact at speed versus height. This is what he said.
Let us assume that the chance of injury to a dog
depends directly on the amount of energy involved in the execution of a particular
The energy involved in a particular jump height is
the gravitational energy or E1 = m g h , where m is the mass of the dog, g = 9.8 m/s2 is
the acceleration due to gravity, and h is the distance that the dogís center of mass rises
when going over the jump. The energy E1 is both the amount of energy that the dogís muscles
must generate in jumping, and the amount of energy that the dogís body has to absorb in
landing. Because E1 is directly proportional to h, the jump height and energy grow at the
same rate. For example, if the jump height is increased by 40%, the gravitational energy E1
is also increased by 40%.
The energy involved in the speed of the dog is the
kinetic energy or E2 = (1/2) m v2 , where m is the mass and v the speed of the dog. The
energy E2 is both the amount of energy that the dogís muscles have to generate to run at
that speed, and the amount of energy that the dogís body has to absorb in stopping. Because
E2 is proportional to v2, the kinetic energy E2 grows faster than the dogís speed. For
example, if the dogís speed increases by 40%, the kinetic energy E2 increases by a factor
Thus, it appears that changes in jump height are
less likely to cause injury than comparable changes in the speed of the dog.
Sue Rolfe & Kes
not being physicistís we tried to put this into laymenís terms and asked him if this was
From this it is apparent that as jump height increases by
40%, impact increases by 40% but as the dogs speed increases by 40% the impact increases by
100%. While watching and running dogs at lower heights it is clear that they go faster and,
therefore, lowering the jump heights for many of our dogs is likely to cause more impact
answer to this question was 'Yes, basic physics tell us this is correct.'
Greg and Laura Derrett from UK Agility have had a lot of experience in working and
training in many other countries where dogs jump at lower jump heights. Both have come to
the conclusion that jumping lower affects the jump style of dogs in a negative way. Dogs
often flatten out over the jumps with a noticeable higher knocked pole rate because of
the lack of effort it takes to get over the lower jumps. Thus less effort is put into the
jump style. It is also evident that many of these dogs have a very poor jump apex causing
them to take off in the wrong place for the jumps, often smashing into the poles. When
you speak to people who are experts in jump style, they will tell you how important
correct body form is to prevent injury and this decrease in style will unfortunately
in countries where we have worked have now begun to train their dogs at 30" even though
their competition jump heights are 22", 24" or 26". This seems to have had a considerable
affect on the dogs consistency as well as jump style.
some of these countries are constantly working on trying to correct poor jump style in
their dogs with lots of work spent on jumping style and a increasing demand for training
days from Ďjumping expertsí from the horse jumping world. Back end awareness, jump
shoots, cavaletti work, ground bars and jump apex is something all agility competitors
would start to have to understand if we brought in a lower height.
observation noted from the countries that jump at lower heights is the tendency for the
herding breeds to have more ACL (anterior cruciate ligament) injuries and surgeries.
Unfortunately, this again is purely observational with no research to back this claim up
but there is a large number of dogs we know abroad with this particular injury in
comparison to only a few seen in British Agility.
competitorís opinion is on what is a safe height for their dog to jump, we have tried to
give them the options to jump both higher and lower. If they feel higher is safer, they
have that option available to them. If they feel the lower heights are safer for that
particular dog, they are still able to have two runs a day in the Casual classes where
they can choose any height.
With all this
information it was still important to make sure that those competing at 30" were happy to
do so. From discussions with competitors over the years along with Jim Gregsonís
knowledge of agility competitorís thoughts obtained from his work for the Kennel Club
Agility Liaison Council and from articles written on the subject, the majority of
competitors seemed more than happy with the 30" jump height.
experience in the UK Agility team it may also be an advantage to the British
international competitor to jump higher in Britain and then jump lower in international
events. Jo, Nikki and Toni certainly proved that in 2003 and Greg did get the Silver this
year. The 30" jump height is certainly keeping us competitive on an international front.
Now we are happy to admit that the reason for sticking to 30" is not a Ďproven factí
that it is better and safer, but everything we could find on jump heights led us to the
conclusion that there was no evidence to change from the 30" jump height while on the other
hand there seems to be a lot of reasons to keep it. If future research were to conclude that
alternative jump heights would be safer, then UK Agility would seriously review itís current
information UK Agility currently has to go by, it is clear that we may have caused a lot of
problems bringing in lower heights. Bringing these new problems in to British agility was
something the British Agility competitor would probably not thank us for!
From Greg Fontaine (Asheville,
I think itís great that people are attempting to
analyze more scientifically what our dogs might be experiencing while playing agility. I am NOT
a physicist; I quickly get lost over my head in this stuff. A bio mechanist I used to work with
referred me to a website with various models that can be used in pre-college math and science
classes. (These days, even pre-college math and science materials can often leave me
A relevant model for this discussion involved a comparison of two
different types of ski jumping events. Nordic jumping stresses distance travelled.
Aerial freestyle jumping stresses height attained (higher heights
mean greater air time allowing more time for spins, twists, etc). The model analyzed landing
impact forces for the two different types of jumping events. You can read the details at:
In the ski jumping examples, the flatter trajectory of the Nordic
jumper resulted in less impact force; the rounder trajectory of the Aerial freestyle jumper
resulted in more impact force. Admittedly, dog agility is not ski jumping. However, the model
and its discussion are just one example suggesting that in analyzing impact forces from landing
different trajectories, there would appear to be much more to the question than merely
calculating the energy involved executing the jump.
It seems perhaps even more important to consider how that energy
is absorbed or deflected as the jumper returns to the ground. Angle of descent relative to the
ground would seem to be one factor. Add to that, the question of whether the jumperís
horizontal velocity will be allowed to continue forward or instead be expected to turn sharply
upon landing. A higher trajectory might mean less horizontal velocity, which would be
beneficial in preparing for a turn. Then again, it seems counterintuitive to expect dogs (and
humans) preparing to turn to typically resort to jumping higher and higher in order to lessen
horizontal velocity; instead I would expect a tendency to shorten stride. That logic would
suggest that jumping higher and higher might not be the most effective strategy for dissipating
Anyhow, I look forward to the possibility of more input from those
with greater physics intellect and practical knowledge than I can apply to such questions.
In any event, whatever the jump heights, best wishes to UKAgility