More Physiology of Warming Up

Last post I noted the mental aspect of warming up for the human sprinter, the monitoring as the body revs to peak performance as the athlete makes a "decision" that the warm up has completed, the body prepared for the event, the subconscious physiological checklist gone through and readiness achieved.

Relying on my memory, here's the checklist:

1. Increase in heart rate and efficiency speeding up O2 delivery, changing blood viscosity, engagement of the NO2 (nitric oxide) mechanism to achieve capillary dilation..
2. Increase in temperature of the body tissues.
3. Engagement of the energy pathways--ATP, glycogen, and O2 uptake by cell mitochondria, increasing the rate of metabolism and efficiency.
4. Engagement of the endocrine system, release of adrenalin.
5. Speed up and increase in efficiency of nerve impulse.
6. Increased force of muscle contractions, bones and cartilage tighten to withstand impending force.

Books have been written on the above, but it is Tom Iver's that really nails it when you're watching a horse being walked to the gate.

Ivers illustrated the warm up using an analogy involving a leather belt. You grab both ends of the belt, pull it apart as forcefully as possible and try to break it. The belt is the individual cell, muscle, bone, etc. it hardly matters, if you apply enough force with enough speed you're liable to snap the belt. However, if you tighten gradually you may apply exactly the same force and the belt will hold. Ideally if our horse were the belt or any cell of the horse the belt, we'd want to avoid snapping it forcefully apart and tighten gradually instead, which is the goal of appropriate warm up.

Ivers provided a colorful description of the magnitude of the physiological forces at work:

"The countdown begins when the saddle goes on. A peaceful heart lumbering along at a restful 34 beats per minute accelerates to 60 immediately, the ears perk up and the eyes come alert. Going to the gate, the churning muscle revs to more than 100. The gate opens and a hundred things happen at once. A million muscle cells fire their pent-up, barely contained power and send a shock wave-over suspensories, tendons, ligaments, cartilage and bone-right into the ground. Adrenaline begins to flow, triggering the spleen to start its contraction, spilling millions of fresh, new red cells into an ever-quickening stream of blood. The 'motor' revs to 140, the hoofs stamp into the ground, and with a singing of tightly stretched tendons and ligaments accompanied by the percussive snaps, pops, and groan of bones and joints locking into place, the equine athlete becomes air borne. Almost immediately a shudder goes through the entire body as the cannon bones, knee joints, fetlocks, and the suspensory system absorb 10,000 pounds of hammering concussion. Another thundering jolt is followed by a powerful acceleration as, again, millions of muscle cells fire simultaneously and drive the twin pistons of the hind legs deep into the racing surface, the forelimbs lifting for flight..." (from "The Fit Race Horse 1983")

That's the physiology. Next post I'll get into specifics as to how all this might work for the horse.

Today's Training:
Art's left front was reshod, and then here is what we did. Art was trotted five times around the paddock with the older horses pre-workout. I do this to try to get them to pass manure and decrease weight since rider Mr. Nob is so heavy. In the trotting Art was still limping slightly. I decided to limit the exercise to tack work instead of galloping riderless. We rode the other horses to near dark. I tacked up Art, cleaned out his hoofs and there was a large obtrusive rock stuck in commisure of his right front. That probably explained the slight limp. This was removed and we detected no further limping. I'm starting to get distressed about this horse's failure to grow. I've had very few youngsters do a lot of growing after the midway point of two year old year to which we're rapidly approaching.