Hey hope the link works, it looks like the leash above. I bought a jac trac one because walking hands free is so much easier, but you can get the same effect with a 6 ft leash around your waist.
It's very hard doing obstacles w. a bully at first! They are lazy stubborn and headstrong. Don't worry about the looks you'll get from people, the looks from your dogs are worse! Poppy gave the best "why mom, WHY?" look but we kept pushing through. These days I always get a loose leash walk from them and they always "check in". I guess the point is that mental exercise is just as important as physical exercise. In the house whenever I speak they listen, and it is so refreshing not to be tense every time I stuff a kong or throw toys for them. I feed a raw diet, and I can leave raw meat on the floor and make them leave the room w. a verbal command.
Also as a warning in case they do something wrong I say "aaah!" (any word you choose) in a low manly voice, and it really freaks them out. Haha! My dog trainer said your high voice=playing, affection or weakness, whereas your low voice means business.