Hey Glen there are no specifics on tracks. One would thing there would be but there isnt anything set in stone. The only Constant is that the pull has to be 16ft so you naturally need at least a 20-24ft track. The width of the track and the cart vary all the time. This is one reason you have to learn your dogs and know the tracks. My biggest example that I always talk about is the ADBA track in NC. This is a very tought track with a hole shot. Its about and inch lower right of the begining once you get about 2 feet out it levels off but it is also very tough, it doesnt roll smooth so you have to bring your dogs in EARLY on this track.
Now also in NC at a different club they have a SUPER NICE LEVEL track. Weight rolls easy and you can wait longer to bring your dog in.
As far a building muscle on your dogs, go with a carpet mill. Walking and slat mills tone and build wind where a carpet mill will build more muscle than anything else.