This is the latest information that has come from Dr Christine Zink on what sort of exercise is appropriate for your puppy at what age.
The information has come from her own experience and research and are guidelines, not rules.
It is important to be careful with your puppy so that you can protect their joints however you do also need to exercise them so they strengthen their ligaments and grow muscle. It is a balancing act and there is no exact science as to the best way to exercise your puppy without over doing it.