All sports you do will have an obedience foundation
Actually with agility it can be started very young. You start with doing obedience for agility, body awareness games and intro to low equip. NO jumps at height they either do poles on the ground or very slightly elevated and also lower equipment heights for a frames and dog walks which will start on the ground as just planks and boards.
Dogs should not be jumping at height until at least a year but for me personally I would wait until 18 months to two years for full jump heights. At a year the pup is Still not fully developed and may be uncoordinated and lanky
I also think pups/dogs should have a health screening and OK from a vet to do most physical sports
here is a link to my on-line puppy/beginner agility class
http://www.pitbulltalk.com/viewtopic.php?t=3115
With weight pull though I don't compete ... no full out pulling of heavy weights until the dog is a year but better at 18 months to 2 years
You can start out though young getting just used to a harness and just drag it around then when the pup gets older gradually add a very very small bit of weight as the pup ages
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