As far as moving, strong rears track straight, the don't swing out, "wing" out, pigeon toe or swing in. The back foot is lifted slightly, the hock and knee bend just enough to clear the ground. The foot reaches well up under the body and is planted firmly. All the motion and energy goes into smoothly and strongly propelling the dog forward, it is NOT wasted in lateral movement, crossing over etc... Nor do the rear legs interfere with each other or the front legs. Roll is created by the single tracking in rear, the fluid (not stiff like a bull terrier double track) tracking in front, adequate rib and drop and the fact that the low tail set and wheel back mean the dog is expending it's energy up under its self not kicking back behind its self.

Bulldogs do have drive in the rear, they are not all "front wheel drive" BUT they should not have a lot of kick up in the rear nor should the foot be lifted too high off the ground. That being said, a dog with a good rear should be able to go "off road" and use his/her shoulders, elbows, wrists, knees, hocks to bend. flex and get easily over rough terrain. A dog so stiff or restricted in movement that tall grass or soft sand makes moving at a trot impossible is not correct, remember "unrestrained, free and vigorous"

Think working cow or cutting horse. These athletes need to do the same turn, crouch, spring and stop bulldogs would have needed to do. They also have a low set tail as they need to work with their rear legs up underneath as well. Deep "hip" from front to back, moderate but apparent angulation, well let down hock which means that the distance from hock to ground is short. From the rear, the legs look mostly straight, with the hock approaching slightly, not a lot, and the toes angled out just a bit. Obviously muscular, but not round or beefy.