Re: Drafting biomechanics
Sherri wrote: Okay folks, I have a question. I was at a seminar this weekend for canine structure and the question came up as to whether a dog uses their front or rear to pull with. My initial reaction was their front, but after thinking about it further, I think it's much more complicated than this. I think terrain, weight load, not to mention the type of harness the dog wears all affect how they pull and drive. My therory is that they use both front and rear, sometimes equally and sometimes one is used more than the other. After watching a video of a Swissy at a weight pull, it seemed to me the dog was using its rear much more than its front. I don't have any proof that this is the case, but I can tell you the dog squatted its rear down, kept his rear feet planted, and pushed with the rear. The front end of the dog lifted up and the front legs seemed to claw at the ground in an effort to keep the dog going straight (instead of arcing around on the end of rope) more than pull the dog forward. Now maybe with a carting harness that has stays the dog wouldn't feel like it could swing around and thus would be able to use more of its front for pulling. I just don't know the answer to that. John Engstrom Plano, TX _ Add photos to your messages with MSN 8. Get 2 months FREE*. http://join.msn.com/?page=features/featuredemail
Drafting biomechanics
I always love talking about this subject. Biomechanics is a fascinating subject in and of itself. First of all consider your first sentence . The Dog is actually PUSHING the harness which transfers the momentum to the cart through the traces and/or the shafts depending on how you are set up. At no time does the dog pull the cart strictly speaking. As for what does the work, it take both the fore and aft legs to get forward motion. Looking at the physics of it, the rear legs contribute more towards the forward motion because of more muscle mass and the leverage of the muscles that contribute energy onto the harness. Because of the angles involved, the front legs would never be able to generate the same forces as the rear legs because their position relative to the front of the harness. Just think of it as a jumping exercise in which the feet remain of the ground. In a jump the front feet do lend initial momentum to get the body into proper attitude for the jump but the rear legs do the majority of the work to get up and over. Just consider how you feel when you try to lift something with your back instead of squatting over to lift with the legs. You are more powerful using your legs and could put your back out, doing otherwise. A good resource for this is Jumping from A to Z, by Christine Zink. Just think jumping on the level ground! Jim LaFrom San Jose, Ca now get out there and work dem workn'dogs
Re: Drafting biomechanics
Sherri, I can tell you they can't pull without the rear. I participated in a weight pulling demo once years ago. My berner was cart trained but not weight conditioned and she was 7 yrs old. We started with about 10 dogs including Sibs, Mals, a Great Dane, some GSs, Sammys, and other pure-bred dogs. Each dog pulled on level to slightly sloping up hill ground and we started with a 100 lb gig (3 wheeled thingy) and the dog had to pull this from a dead stop a distance of about 16'. All the owner could do is call the dogs name. After each dog had a try those that didn't/couldn't pull dropped out and they added weight at about 50 lb increments after each round of pulls. At the 550 lb level the four dogs left were my Jeni, a Mal and a couple other sled dogs (either both Sibs or a Sib and a Sammy) The Dane and a GS didn't even make the first pull because they didn't have the proper rear for digging in and driving forward. Too much angulation in the GS so energy was wasted. This is of particular concern in our Berners today as many many have too much bend of stifle and couldn't pull a load on their best day. Sandie Hawkins
