Endurance.Net Ridecamp Archives

Truman,

You have made this system too simple. Try walking half a mile on level ground at a comfortable pace. That shouldn't be much of an effort for anyone fit enough to ride a horse 50 miles in a day. Next, try hopping half a mile in the same time,  but jumping at least six inches high at every hop. By your theory, the same amount of  energy was used. Gravity hasn't changed, your mass hasn't changed.

But that's not what happened, was it? Hopping got your heart rate up, required more strength, and used a lot more calories. What changed? The amount of wasted energy did. You used additional energy to propel yourself upward with each hop, and again to deliver that energy back to the ground without breaking your legs with each landing.

In a similar manner the rider, by moving "with" or "against" the horse, can determine in a big way the forces necessary to propel the horse/rider combination upward, forward, or laterally. When the rider rises from sitting to standing in the saddle, the force to acclerate the rider upward must come from the ground, through the horse. When the rider returns to the seat, the horse must deliver the force necessary to stop the rider's downward motion (again an upward acceleration) from the ground to the rider. Since the goal is forward motion, neither the standing or the sitting (or the other, downward, acceleration when the rider begins to move from standing to sitting) contributed anything, and both of the upward accelerations resulted in wasted energy for the horse.

In posting, we seek to more than offset that waste by smoothing the forward motion of the rider, thereby reducing the amount of front-to-back force that the horse must deliver from the ground to the rider with each stride. The rider's undertstanding (whether intiutive or scholarly) of the physics of posting, the rider's skill in execution, and the rider's physical strength all become significant parts of the equation.

Posting is the most visible case, but this matter of making it possible for the horse to smoothly deliver forces from the ground to the rider is an issue at all gaits. Each horse and rider (and day, and trail, etc.) is a unique "system" and performs this task with a unique efficiency.

Steven Estergreen

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