It would probably be a good idea to dedicate a series of posts to kinetic chain development, but I just need to get this thought out there. Especially in light of Vibram settling a law suit suggesting strength of muscles reduces injury.
When I was a silly body-building weight lifter, tracking diameter of biceps (seems so silly). I would target muscles and do isolating exercises to make them stronger (again, very silly). Some muscle groups responded well, others not so much. I struggled to know why.
For example, thin wire'y calves. Lifting tons of weight on a calf-raising machine made no difference in large calf muscle size. Besides the obvious 'who cares', I thought I narrowed the reason why. The calf is a link in a chain. You can't make certain links of a chain stronger than others, it makes no sense. My Achilles tendon (through genetics? or whatever the reason) was as small as a #2 wooden pencil. People with large calves had thick thumb-width Achilles.
After a few years of running, using thin (or no shoes) my calves are getting functionally stronger BECAUSE the entire chain is strengthening. As you'd expect, my Achilles tendon is two times thicker. Tendons, ligaments, bones, muscles: they all react and adapt.
Adaptation is a reMARKable thing.
A good source that describes bone mineral density, tendon and muscle adaptation, check out the book 'Brain Training For Runners'.