12,000 Lbs/sq. Inch, Is it True?

Here's the leg, above. Notice particularly the long p1 (pastern closest to fetlock).

And, do look at the illustration in yesterday's post for a superb visualization of the manner in which force affects these equine leg bones at speed.

There are actually various types of force but primarily

tensile forces
compressional forces
torsional forces

and these refer respectively to concussion, weight bearing, and the circular force of movement itself. To torsional forces we may add the "bad step" as another source, and in fact the torsional force is the force to which the bone has the least resistance.

So when we hear people such as Tom Ivers bandying about numbers that the equine leg at speed undergoes 12,000 lbs/sq. inch of force, quite obviously this is at best a gross generalization to make a point, and probably bears little reflection on the actual physics of the equine leg at movement.

Probably some unknown vet sometime did some measurements and that's were the 12,000 lbs comes from. Since I'm unable to find the research, instead of belaboring the point and trying to break down the physics, let's instead acknowledge the following:

1. Unquestionably there are powerful forces working on the equine legs at speed. For confirmation of this saddle up, get on board and gallop one down track at 40 mph. As you approach that final turn at speed going into the left lead change on your fairly hard track those front legs are pounding into the ground with every stride. You can see them, hear them, feel the force of each stride shuddering through the horse's body.
2. The horses handle these forces most of the time.

How does the bone structure hang together against the powerful forces exerted on it. Probably numerous ways, though you'd think primarily of dissipation of force and the momentary nature of the force. I'd guess also that The Force, whatever it consists of, probably changes its exact target slightly depending on the particular stride motion thus sparing any one area from continual pounding. Additionally, we talk of dissipation of the force both in the single leg but also from leg to leg as the horse does it's sequential footfall down the track. And so, whatever force is coming at it, the horse quickly whisks away generally before any damage.

I'll end it this post but volunteer that as a rider my perception of all this is that the horse bearing the force of racing speed is a very fine line. And, it's this thin line of the horse bearing up to these forces (plus a few other traits equine) that have me as I go down the track planning my exit with every stride.

Today's Training:
Sunday night began to get the sense on an overcast day that things were starting to dry. At least the horses could find somewhere around the barn where they could stand without being in a puddle. Art has done nothing due to weather-abscess combo since June 22.