Came across this on my fb page. At first glance, the guidelines seem more conservative than what has typically been recommended here. Thought it might be an interesting read.

https://puppyculture.com/appropriate-exercise.html

Amy, that is the guideline I used for Sofie. We here typically say similar and really emphasize the 5 minute rule and the soft surface rule. As the adult sized dog goes up the more of these rules need to be followed, so with a standard husky the risk isn't as great compared to say the standard gsd. There are several studies that I read before getting Sofie, the one you just posted does come from an actual study believe thru Penn State (which were the original place that developed the Penn Hip test), I believe it may be UC Davis that recommended not to spay/neuter prior to 1 year for medium sized dogs and smaller and upwards of 2 years for large size dogs and up because of growth plates, in fact they took a look at rescue pups that are typically speutered as puppies, often times around 8 weeks old and their growth plates stayed open longer than the standard breed that was compared that was speutered at 1 year. For a good chunk in time most scientists believed that HD was almost always hereditary, today they believe that is only a small fraction of determining HD. Most say that it is possible that damage is done at birth thru 1 year of age, and stricter guidelines for breeders and puppy buyers has been introduced.

I can find certain studies if interested. One that I found very interesting was whelping boxes, that if a breeder mimicked wolf dens the chances of HD is lowered, since HD is not a common problem in wild dogs (wolves, coyotes, etc). When I chose my gsd breeder I considered the Penn Hip scores as well as OFA scores for the sire and dam as well as their lineages. I then followed the guidelines that you posted, and I did wait until after her first heat and at 10 months did her spay, her growth plates actually closed much earlier than common gsd's, which I found odd but every dog is different, Sofie is smaller than both her dam and sire, and slightly smaller than her siblings, yet was in the middle in size as puppies when I took her home.

Thanks for posting a very valuable link you posted!