Puppy Exercise - What is appropriate?

Self Directed Play is an overriding rule for any puppy under 18 months old.  The majority of his/her exercise should be free play, exploring, and investigating his/her environment.  If your puppy shows any fatigue, flops down, refuses to walk, you should listen and let him/her rest. Exercise not only builds the puppies' bodies, it helps build their minds.

Puppies naturally exercise in small bursts of activity, not sustained walks.

But exercise that’s not appropriate for a puppy’s age and development can cause significant and irreversible damage. What would be a simple sprain in an adult dog could leave a puppy with a affected limb, and should be taken seriously.

Growth Plates in Puppies
The first consideration with puppy exercise is their “growth plates.”  Growth plates are 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 until the end of puberty. Growth plates gradually thin as hormonal changes approaching puberty signal the growth plates to close.  In puppies, this closure is normally completed by approximately 18 months old.  Until the growth plates close at around 12 months of age, they’re soft and vulnerable to injury.

A dog’s bones are held together with muscles, tendons, and ligaments - soft tissue.  In a puppy, however, his muscles, ligaments and tendons are stronger than his growth plates, so instead of a simple sprain, his growth plate is likely to be injured - the puppy’s own soft tissue can pull apart his growth plate.
This matters because  unlike a sprain, injuries to the growth plate may not heal properly or not heal in time for the puppy to grow up straight and strong.  In addition to having soft growth plates at the end of long bones, a puppy’s bones in general are “softer.” Dogs, like people, don’t reach their maximum bone density until after puberty. Spiral fractures of the tibia (lower leg bone) are very common in puppies - 50% of all fractures occur in puppies under 1 year of age. 

Puppies don’t have the cardiovascular system for endurance.   Long walks and exercise sessions increase risk of injury and are not necessary  until the puppies have grown up or you decide to train for agility.
 However....  this does not mean you cant let your puppy play.
Its important you introduce appropriate exercise for your puppy - appropriate exercise is is not dangerous for your puppy, exercise has been shown to increase bone density.
 
GUIDELINES FOR PUPPY EXERCISE
Exploring at Their Own Pace
Exploring low rock walls and gardens at their own pace is great mental and physical exercise for puppies.
Self Directed Play
is an overriding rule for any puppy under 18 months old.  The majority of his exercise should be free play, exploring, and noodling around. If he shows any fatigue, flops down, refuses to walk, you should listen to him and let him rest.
Digging is Good for Your Puppy
Never underestimate the value of a good digging session. Consider digging up a soft patch in a corner of your garden and burying “doggy treasures” in it - great natural exercise for your puppy!
No Repetitive Exercise
Probably the biggest cause of growth plate and soft tissue injury is repetitive exercise with a young puppy.  So, until he’s about 18 months old, long hikes and walks are out and lots of free-play sessions are in.
Playing around in the backyard with you is great.  If you don’t have a backyard, short, slow walks, giving them the opportunity to sniff and explore at their pace is perfect.  You can add short training sessions in your walks to work on heeling/loose leash walking, but the majority of the walk should be at your puppy’s own pace. Long hikes are not suitable for puppies.
However, if you love the outdoors, you should bring your puppy along on hikes - its great socialisation for puppies less than 12 weeks old, and great enrichment for older puppies.  Be prepared to carry your puppy a good portion of the way.  If you’re jogging or walking on a manicured trail or paved park road, consider investing a puppy stroller to put your puppy in for most of the walk.
Long walks with a nice stroller are great for everyone, don’t be frightened to pop your puppy in a troller and go for a long walk yourself. They will love the socialisation and its great for your well-being.
Kibble Trails
Kibble trails are also a great way to tire out a puppy both mentally and physically.  Remember, dogs generally don’t naturally go on long “marches” - they tend to amble around and stop and sniff a lot as they go. 
Kibble trails allow puppies to stay outside a long time and cover a lot of ground in a very natural way.  Place a portion of the daily kibble allowance in a trail around your yard; the puppy will search for it on your morning walks.
Play Mates
Play with a well-matched and gentle playmate is ideal.  Size is a factor, as a very large dog, especially one that likes to play with a lot of paw whacks, can inadvertently injure a young or small puppy.
Remember to ask if the other dog is gentle like to play with puppies. .  Keep a very careful eye out and be prepared to throw handfuls of cookies down to interrupt any overly physical play.  Body slams and crazy rolls are spiral fractures waiting to happen!
Enjoy exercising with your puppy appropriately !!!