Just because it goes “across” the legs, does not restrict movement because it is loose. If the dog's legs are moving freely, nothing is pulling the harness back, so there is no way it puts any pressure on the front strap.

Do harnesses restrict shoulder movement?

It is important to fit the harness properly and ensure you're your dog is able to move their shoulder through his/hers full range of motion. Although most “no-pull” harnesses are designed to restrict shoulder movement, there are some harnesses that have been designed to allow proper movement through the shoulder.

Why you shouldn't use a harness?

Can be harder to put on and take off. May require more physical strength than walking your dog on a traditional dog collar, depending on the size of the dog. If a harness is too big, your dog may be able to wiggle out and escape. Dog harnesses that are too tight can be painful for dogs.