Bone Size and FR

A few bone cross sections photos this post illustrate my belief that bones probably have genetic, pattern, function etc. limits to their growth regardless of exercise stimulus. The familiar (on this blog) calf cannon photos above show inward bone growth of calves trotted five minutes a day for 4 or 5 months compared to the confined. I'm thinking that most growth occurs in the early stages of progressive exercise, and most of this growth is inward.

Some of the physiological limits can be seen by the next illustration which shows
the osteons, and also collagen layers both outside and inside the osteons. Probably bone growth will occur mostly in these external and internal collagen layers. The total number of inside layers will be limited so that enough spongy bone remains to cushion the medullar cavity. Possibly the outside layering just under the periosteum will be limited as unfettered growth away from the osteons might destabilize the structure. I think that there will be some outside growth but that most of this occurs early in the exercise program.


As to the question whether osteons will grow in size in response to exercise, these slides of actual bone show the limits of that process as we see osteons compacted in tight quarters seemingly without room to expand!


If my suppositions are true then, the important growth in bone size takes place earlier in our exercise program than the final honing down of the cannon bones to race appropriate FR, i.e. we will have at that stage other issues than overall bone size or thinking we may thicken the osteons or increase their numbers.

This leaves for our speed work program to FR what has already been covered:

increases in density of the matrix, bone glue volume and calcification process (to which more thought needs to be given. The good news of all this is that we are therefore probably talking about remodeling process that we can actually influence by what we do on the racetrack!

Tues. 8/18: training recommences in the mud for both horses tonight.