There is an idea that has caught on that exercise will eliminate all puppy related behaviour problems. This is not true and can lead to owners pushing their puppies to dangerous and inappropriate levels of exercise.
Strong Minds in Strong Bodies
Appropriate exercise helps build puppies minds as well as their bodies. Exercise has a very particular and important role in brain growth and improves learning, memory and emotional response. But, exercise that is not age and development appropriate can cause significant and irreversible damage.
Understanding Puppy Bodies
Let's consider growth plates. Growth plates are the soft areas that sit at the ends of the long bones in puppies and young dogs. They contain rapidly dividing cells that allow bones to become longer. Growth plates gradually close and calcify and this closure is normally completed by 18 months. Until this time the growth plates are soft and vulnerable to injury.
Puppy's muscles, ligaments and tendons are stronger than his growth plates which makes the growth plates liable to be injured. Injuries to growth plates may not heal properly or not heal in time for puppy to grow up straight and strong.
Self directed play is an overriding rule for any young puppy. The majority of exercise can be free play, exploring, digging and noodling around. Climbing stairs are not the best for young pups. There have been studies that have found that puppies who climbed 'flights' of stairs daily before they were 3 months of age had an increase risk of developing hip dysplasia. Although the labradoodle is not prone to hip dysplasia it indicates that stairs represent a strain on any puppy's joints.
There are lots of guidelines for many types of exercise, but the most common questions are regarding running, walking and agility.
Continuous Walking - sustained or continuous walking to be slowly built up. At around 6 months - 30 minutes walk is acceptable. Increase gradually and if puppy appears tired or reluctant you should back off.
Running - No directed running (going for a run with puppy's human) except for short spurts in play until puppy has reached maturity approx 18 months. Puppy can run as much as he likes on his own. Running and endurance training can gradually be introduced around 18 months of age.
Agility - Usually starting at 18 months of age.
Puppy Fitness That Fits The Puppy - by Jane Messineo Lindquist (Puppy Culture)