Rider Role In Stride Efficiency At Speed.

Some posts ago I'd worried about inadequately gripping race plates on turf as one indicator of questionable trainer. You can look at the horse and tell, provided u know what to look for. And then this. they do slip and fall on turf without the right plates:
http://www.bloodhorse.com/horse-racing/articles/66470/chavez-to-miss-five-months-due-to-injuries

The 3/2/10 Rachel video gives an excellent view of Rachel and Asmussen's superb exercise rider, ex jock Dominic Terry and Terry's technique. Is he doing anything in terms of stride efficiency since Rachel's stride is so obviously superior to the other horse? In fact, viewing that other horse, interesting what if anything might be done to improve her very flat stride. Watch the vid in terms of what the riders might be doing to affect the horses' strides:

http://www.youtube.com/watch?v=7za5GH86Jik&feature=related

If you're like me, and strictly closely watching this from the ground, I am unable to see anything that visibly shows that either rider is doing in terms of stride efficiency. I do notice that D. Terry is a perfect rider sitting chilly directly over the center of gravity, displaying rider body lean and arm action that perfectly goes with the stride of the horse whereas the other rider is a little heavy preventing full lift of horse's rear end, and he sits a little in front of center of gravity. Certainly questionable riding techniques can unbalance the horse. But is there anything the perfect rider does in a positive contributory sense that affects (improves) stride efficiency?

The round about explanation goes back to the last posts on the mechanics of the stride at speed. Certainly at the slower speed there are numerous rider techniques affecting the stride. At max speed, however, my take, and I get this closely watching my horses at speed, there's only "one" style without any other styles being possible, when the horse's lead rear is pistoning back and forth as fast as possible along the axis of the hip. The horse is without a "more efficient style of this" and therefore there's nothing really that the rider can do to affect this max speed stride except to use all the correct riding techniques of which D. Terry is a superb e.g.

Does then the jock playing around with the bit affect the lift or bob of the horse's head to get more efficient bounding action and body propulsion as the front legs thrust forward? Are there different more or less efficient ways of this for this horse?

Again, at slower speeds there are noticeable variances of front leg and body propulsion depending on rider techniques. At slower speeds it's possible by technique to "lift" both the front and back ends of the horse. This is likely where Tom Ivers got the dressage term "rounding on the bit".

At max speed or near max speed however, I am fairly convinced that the sole emphasis is on max turnover rate, and that when the legs are churning as fast as muscle contraction permits, there's very little positive the rider can do to make this more efficient, although there's plenty in a negative sense that many riders do to interfere with this.

So the Q--the jock that comes up to me and brags that "its all in the hands" and he has superior hands--- of course. Is this true--is there anything going on with hands/rein/bit that affect stride efficiency? Think I've already answered, but elaborate, next post.