How can I compare different dogs' performance given these values?

[BryanS]

I haven't given much thought to the physics I studied in college a long while ago but found myself pondering some things recently and wanted to explore some thoughts... figured it might be a fun area to discuss and you might help point my brain back in a good direction...

I regularly participate with my dog in an event called "Fast CAT." The event has dogs chase a lure, which is essentially a plastic bag attached to a string, along a straight, flat plot of ground. Optical timers are set 100 yards apart to measure the total time that it takes for the dog to travel the 100 yard distance.

Dogs are compared by how fast they run. My dog, while quite athletic, is roughly 96lbs and isn't quite as fast as some of the lighter dogs of similar height. It got me thinking that there must be some way to include weight in doing some comparative calculation rather than just the typical calculation of distance and time gives us velocity that I'm so used to considering. Maybe my goal was to figure out the relative effort of various dogs rather than just compare them only based on average speed...

Given the weight of the dog (96lbs in my case), distance (100 yards in this case), and time (typically 9.2 sec or so) what can I actually calculate? I'd been looking over some power formulas and work formulas but wasn't sure if I was misinterpreting anything. Also, if other data points were collectable, what other calculations might be of interest.

Since pics make everything more fun, here's a photo of my dog running in one of these events

 

[jbriggs444]

I've always thought that an important figure of merit is leg weight. In order to run for 100 yards, the legs have to cycle from top speed forward to top speed backward many times over the course of the race. The rest of the body only has to be accelerated from rest to top speed once. In the absence of any spring-like energy recovery mechanisms, energy requirements are going to scale directly with leg weight and inversely with stride length.

One would expect to want long bony legs with beefy muscles attached high up.

 

[A.T.]

Maybe my goal was to figure out the relative effort ...

A race is about being the fastest, not about wasting the most energy. Get another dog or find a different discipline for your current one.

 

[BryanS]

I've always thought that an important figure of merit is leg weight. In order to run for 100 yards, the legs have to cycle from top speed forward to top speed backward many times over the course of the race. The rest of the body only has to be accelerated from rest to top speed once. In the absence of any spring-like energy recovery mechanisms, energy requirements are going to scale directly with leg weight and inversely with stride length.

One would expect to want long bony legs with beefy muscles attached high up.

I hadn't really considered that impact; I know there are significant structural differences in dog breeds that make some better suited for running fast but you're definitely describing some of the structural traits of those on the faster end of the spectrum. AKC publishes the top fastest runs, searchable by breed, and if you compare something like a whippet which has long, lightly boned legs with most of the muscle relatively high on the leg vs a bulldog where the leg is more heavily boned with less length and the muscle occupying more of the overall length, placing the mass lower on the leg, you'll see an average of the top fastest being ~37 mph vs ~19mph

 

[BryanS]

A race is about being the fastest, not about wasting the most energy. Get another dog or find a different discipline for your current one.

You're absolutely right in the context of being concerned about being fastest. In the big scheme of things though it's all about doing something fun with your dog and there are a lot of dogs that are relatively slow but go nuts at the opportunity to chase something moving... nobody is getting sponsored by big corporations or bringing home a fat check so the purpose is really about having fun. AKC catalogs all the results and doesn't even make them searchable to see overall fastest; they do make them searchable based on fastest among a given breed so they seem to encourage comparison among dogs of similar structure. They also weight the results based on height giving the shortest dogs a multiplier and creating a scenario where a 20mph dog @ 11" tall actually scores better than a 38mph dog @ 19" tall. For my own curiosity I'm just considering how I can do something similar based on weight... I'm of no delusion that my 96lb dog is "better" at this sort of "race" and participate in a wide variety of disciplines that she's less than ideally suited for... we still have a blast anyway :)

 

[Dullard]

I would divide the weight of the dog by the 'seconds/100 yards' value and divide that by 100. The dimensions would be:
Yard Dog Pounds / second.

 

[CWatters]

About the man that has to out run your dog while towing a plastic bag on a rope... Do you have to pay him or does your dog just have sharp teeth?

 

[sophiecentaur]

. I'm of no delusion that my 96lb dog is "better" at this sort of "race"

But you will love him no less for that. It strikes me that what's needed here is a handicap race, with weights strapped to the leaner and meaner dogs (based on past performance) so that they all arrive at the finish at a similar sort of time. This is done in horse racing (I can't get on with the whole idea of betting on sport, though) so it can be made to work. A great advantage of such a system is that the result of a race is not predictable until the final few seconds, when everyone is in with a chance.

I often see people road running, just for training purposes, and I am amazed at just how badly they move - all up and down and rolling etc.; so inefficient. But i remind myself that they are only doing it to get fit for some other sport so their efficiency at running may be irrelevant.

If you were really interested in having a dog that wins races, no doubt you would buy a greyhound.

 

[Nugatory]

A race is about being the fastest, not about wasting the most energy.

Many speed competitions use some sort of classification system, so that competitors are ranked against other competitors subject to similar limitations as well as the overall field. For example, an autocross will put unmodified daily drivers on the same course as race-prepared cars that arrive on trailers. Naturally the latter usually turn the best times, but a handicapping scheme (the PAX system - it is far from perfect) allows the drivers of slower cars to compare themselves against others driving similar cars and to evaluate whether they're getting as much out of their rides as is possible.

My first thought on reading the original post was that we might be looking for something similar here: a way to recognize which dogs are doing the most with the genes and body they have to work with. However, I'm very skeptical about this - with enough time, tools, and money we can turn a car into anything, but a dog is not an engineering project.

A question for the original poster... What breed/mix is your dog? From the photo (which suggests that he/she is having the time of their life running even if they aren't finishing first) I would have guessed bull terrier, but 96 pounds is way too big for that.

 

[CWatters]

Dogs are compared by how fast they run.

That's a test that will favour different breeds of dog or dogs trained to produce certain types of muscle. So I think you could only reasonably compare your dog to data from dogs of the same breed?

Perhaps suggest they introduce a strength competition? How fast they can pull 1/2 or 1/4 of their body weight in sand bags over 10 yards or something like that? Perhaps consult animal welfare groups first!

 

[A.T.]

They also weight the results based on height giving the shortest dogs a multiplier and creating a scenario where a 20mph dog @ 11" tall actually scores better than a 38mph dog @ 19" tall.

So they are measuring speed in body-heights / s instead of m/s. Makes sense given the size differences between dogs.

For my own curiosity I'm just considering how I can do something similar based on weight.

In the above example a bigger dog get penalized. You want to give the bigger dog a bonus for being so heavy.

 

[A.T.]

I'm very skeptical about this - with enough time, tools, and money we can turn a car into anything, but a dog is not an engineering project.

But if you want to treat the dogs like cars, you would have to track their velocity at any time point. Then you could look at max. acceleration and max.accelerative power etc.

 

[sophiecentaur]

It strikes me that the answer to this question would involve politics as much as Physics. The formula would need to make every dog owner to imagine his pooch is in with a chance of 'doing quite well'. The Paralympics is an example where the class rules are changed and broken all the time. Some things just can't be compared to satisfy everyone. The best way to assess your own dog is to compare performance figures from different races but also including placing, times and, perhaps race conditions. That way you can tell how the dog's performance is progressing , self referenced as well as 'peer referenced'.
As for the Physics of the business, I think that unlike in other applications, Physics is more Placebo than objective. You 'believe he's doing better' and so does he - and he does better.
If the he is a she, then apologies to her.
PS Search these forums for questions involving weightlifting, body building and combat sports. You will see that people are always after the Physical equivalent of the Philosopher's Stone. I don't think any of the threads actually come to a proper conclusion but some of them satisfy the OPs of those threads.

 

[BryanS]

About the man that has to out run your dog while towing a plastic bag on a rope... Do you have to pay him or does your dog just have sharp teeth?

some of the dogs have very sharp teeth and we tie a pork chop around the guys neck to make the game even more interesting.

Actually, they use a complex series of pulleys that are nailed into the grass and run the string around the pulleys to create a continuous loop with the bags tied onto a place on the string. The string is moved by a contraption that uses a large pulley hooked to some sort of drive mechanism and a "lure operator" presses a momentary switch to engage or free wheel the drive mechanism. I've seen an electric motor directly connected to the drive pulley and run from a bank of car batteries and have often seen a contraption that uses a small gasoline engine and a belt that goes from it's output shaft to an automobile air conditioning compressor clutch which is attached to the drive pulley. In the electric version the lure operator powers up the motor with the switch while in the gasoline version the lure operator engages and disengages the clutch to move the lure. It takes a bit of practice because they want to keep the lure at a suitable distance from the dogs of varying speeds (dogs run one at a time in the events I attend though with sight hounds like whippets, et al they run them in packs). Things get really interesting when parts start breaking and you need to go looking for AC parts from an '84 Camaro... been there, done that lol

 

[BryanS]

But you will love him no less for that. It strikes me that what's needed here is a handicap race

They do actually apply a bit of a handicap based on height. Dogs accrue points towards titles that are added to their registered name; a way of recognizing their accomplishments similar to how you see people with esq, MD, etc as name suffixes. Points awarded for height where large dogs (18"+ at the shoulder) get 1 point per mph average, medium sized dogs (12"+ to 18") get 1.5 points per mph, and small dogs (less than 12") get 2 points per mph.

The title structure awards a BCAT suffix at 150 points, a DCAT suffix at 500 points, an FCAT suffix at 1000 points, a FCAT2 at 1500, FCAT 3 at 2000, etc. The highest titled dog is actually a tiny Boston Terrier that my buddy runs which has more than 7,000 points (FCAT13) and the reason is because the dog is still pretty quick but is short. While my 24" tall dog runs around 22-23 mph and gets around 22-23 points per run, this little maniac runs around 20 mph and gets around 40 points per run. If she manages to catch the bag at the end they usually have 3 people holding her upside down and trying to pry the bag out of her mouth... usually they end up cutting the bag off the string and replacing it

 

[BryanS]

What breed/mix is your dog? From the photo (which suggests that he/she is having the time of their life running even if they aren't finishing first) I would have guessed bull terrier, but 96 pounds is way too big for that.

This dog is a 2 year old female cane corso, which is a relatively small mastiff type breed that originates from Italy. Breeds that look a bit similar would be large boxers, bullmastiffs, presa canario. This photo will give you a better idea of her structure. I have another who is now retired from agility competition at the age of 7.

with enough time, tools, and money we can turn a car into anything, but a dog is not an engineering project.

Some people that get over serious about their dog's performance actually do some "tuning" to try to improve. It's not uncommon to try increasing a dog's interest/prey drive in the lure and make them more aggressively pursue the lure. People run their dogs on underwater treadmills to help develop strength. A friend of mine recently told me their dog set a new personal best, gaining 2mph, after working their dog a lot in a dock diving event where the dog, from a running start, attempts to jump as far into a pool of water as they can and that they'd been training by having the dog run sprints with a small parachute. That's all a bit much for me

 

[BryanS]

In the above example a bigger dog get penalized. You want to give the bigger dog a bonus for being so heavy

That was basically what I was curious to do just for my own interest, or rather just take weight into account when looking at performance since it's as much a factor as height.

I wondered, can I calculate power output... can I calculate work... if my dog gets faster but is a couple pounds heavier or lighter what's the changes to those values?

 

[BryanS]

Perhaps suggest they introduce a strength competition? How fast they can pull 1/2 or 1/4 of their body weight in sand bags over 10 yards or something like that? Perhaps consult animal welfare groups first!

Dogs participate in weight pull events where they pull sleds weighted with absurdly big piles of weight... it's amazing what a dog trained and conditioned to pull can move. Along slightly similar lines, sled dogs pull as a job and people have used some breeds as draft animals, pulling carts for work. I've seen pictures of my friend's newfoundlands pulling the owner in a cart in some sort of competitive thing where they have to be able to negotiate a course where they don't knock things over going around turns and such.

If everyone hasn't realized by now, the rabbit hole for weird stuff to do with your dog if you don't have children and have too much free time is pretty much bottomless lol

 

[gmax137]

Perhaps suggest they introduce a strength competition? How fast they can pull 1/2 or 1/4 of their body weight in sand bags over 10 yards or something like that?

see "Call of the Wild" -- pull a heavily loaded sled for 100 yards?

"Horses for courses"