Bone Fracture Mechanics And Warming Up

The smoking gun again. We're ready to lay the wood to the question: does warming up affect bone soundness?

With the RR hand clapping experiment (see July 12 post), answer, yes it does. But, how?

Wish I did have the smoking gun on that, but at least there are some logical suppositions.

Please note:
1. Bone fracture mechanics is a relatively new study.
2. Paul Hansma, the UCSB physicist studying fracture resistance posts:
a. we'll probably never be able to image a fracture happening in live bone.
b. we've yet to fully understand the mechanism of fracture resistance at the molecular level.
3. I was unable to find any studies at all directly on the point of how warm up affects fracture resistance. I even emailed Hansma who replied and asked if I had any stats, and then declined to respond further. Typical researcher tunnel vision. There is Hansma studying the shells of sea mussels, but what could be more ripe for studying the fracture process than thoroughbred race horses?

So, we do some educated guessing based on a little lay reading.
Consider:

Top view: collagen fibril at rest.
Bottom view: collagen fibril under stress.

The above micrograph shows that force affects the fibril, which appears loose at rest and tightened under stress.

The diagram below shows what happens between the (bone) collagen fibrils at impact. Left click to enlarge:

Again, big difference in the bonds between the fibrils which consists of organic bone glue at rest and under stress.

The next diagram shows the mechanical structure of the bonds or "glue" that permits resistance to stress. The concept of the sacrificial bond as part of the mechanics of fracture resistance is a new discovery of the last few years:

Next is a micrograph of some actual fibrils cracking or pulling apart. You can see the bone glue holding them together under stress:

What can we conclude? There's a difference between the bone at the cellular level at rest and under stress. This is a big, big point in terms of the warm up because it does answer the question that warm up in addition to everything else it affect, it also affects the bones.