I have never sold a puppy to a runner before -- I have told them they may not jog with the puppy. I am thinking of putting it in contract but wanted to ask at what age would it be safe to jog with the dog?

I always tell people no forced exercise until the growth plates have closed - no earlier than 2 years of age. If they are avid runners, I recommend a different breed to run with as Labradors were never meant to be long-distance runners.

I have sold a puppy to someone who runs. He is an avid marathon runner and his siginificant other is a vet. He waited until she was done growing and then started her on slow jogs. Now she does an average of 5-10 miles.
At 2 years she was OFA Excellent and Elbows Normal/Clear!!!
She is now 4 years old and has no signs of any issues.

I don't have a problem with runners, it's the ones that take the puppy out at 3 months and start jogging or agility with it that have the problems.

I am a runner. Not before 2 years and then slowly to build up strength. Also great care must be taken during heat because dogs can't cool themselves as well as humans can. I never run with my dog when the temperature is above 70 degrees.