Appropriate exercise amount for 11 month lab

Question
I have a 11 month chocolate lab female. what is the appropriate amount of exercise for her to get in order to not "over-do" it and to avoid any permanent damage to bones, ligaments, etc.?  I have a 7 year old black lab that got too much exercise when she was young and now has a permanent and irreversible problem with one of her back legs. I want to avoid this with the young one. Thanks!

Answer
It is really hard to say.  Don't push it, let her set the pace and quit when she wants to.  While an 11 month old needs plenty of exercise, avoid running an jumping as much as possible.  

Also watch her weight.  Your dog definitely should be narrower at the waist than the hips and chest. You should be able to easily feel the ribs, but not see them. Each dog is different. Standard recommendations are a good place to start, but each dog must have its food and exercise adjusted to its individual needs. Here is a link to a good illustrated guide, http://www.longliveyourdog.com/twoplus/RateYourDog.aspx