Bone Material and Fracture Restistance

The question I left hanging concerns fracture resistance of bone at rest and under stress. If it's the same, then the manner of warming up might be irrelevant. But, if the fracture resistance of bone material increases by gradual loading of stress, then the manner of warm up might be crucial.

My understanding of all this is incomplete, and to that I'd add that I've already posted that the scientific knowledge of fracture resistance is still developing. Moreover, I've decline to buy any of the $40-50 articles on fracture resistance, so, please avoid "boning up" on these posts for your bone mechanics fracture resistance exam. I'm just guessing, putting together, extrapolating from what little is available on the net, though I'll suspect my conclusions to be fairly "right on" even if in some respects technically incorrect.


Stewart Eidelson MD (first bone post) generalized that bone is inner and outer bone called cortical and cancellous. The inner bone is more matrix or lattice while the outer seems a combo of collagen fibers, crystalline salts and various chemical bonds.

Breaking it down further, the morphology of outer bone--collagen fibrils, mineral plates, and an unmineralized, organic material made up mostly of proteoglycans and glycoproteins (txs. Paul Hansma website).

It seems that the mineralized fibrils have various degrees of unmineralized "coating". Some photos from Hansma:

A: fibrils coated with unmineralized organic material
B. unmineralized collagen fibrils
C. mineralized fibrils
D. crack formation



If you look at D above you'll see what looks like some sticky stuff where the crack is pulling apart. Hansma 2005: We're pleased to announce ...our work identifying the existence of a glue in bone."

It's this glue that aids in bone strength and fracture resistance including the nature of it's various bonds that I'll get into next post.

Training:
Mr. Nob stepped on the scale this morning and came in at 160 lbs. That's progress. Hopefully 155 lbs by Sat. We'll breeze the oldsters at the farm Wednesday then off to Eureka Sat. Art as follows:
Thursday July 5: 4th straight day of riderless paddock work. 5 min under tack.
Fri. July 6: off.
Sat July 7: 6 x 3f riderless most of it snappy.
Sun July 8: Off we're at Eureka
Mon: 6 x3f riderless with oldster in paddock. Several fast bursts and a lot of 2 min lick stuff. Strenuous w/o maybe a little too much. Horse seems unsure on footfall and holding back instead of streching out. sore feet again. horse trying to tell me something maybe.
Sat. July 7: