I just came across a study looking at the difference between novice and and advanced riders using muscles sensors. Six ‘recreational’ riders were the novice examples. I presume these individuals rode occasionally, but did not own a horse or take lessons. Their background was not made clear.
But the researchers found ‘more chaotic muscle activity’ in novice riders than in advanced riders. Novice riders either contracted or relaxed the muscles in both arms and/or legs at once. Although the report did not mention it, they probably also tended to contract all four limbs at once.
That is a little hard to track on sensors, because it usually precipitates the prompt parting of ways between horse and rider. Hitting the ground probably causes more chaotic activity than their sensors could handle! However, any riding instructor knows that getting a novice to sit up and relax their arms and legs is essential if the rider is ever going to stay on.
I have not yet found my dream program that allows me to see just how a horse’s skeleton moves, but I did find a way to illustrate exactly how subtle and precise a rider’s aids ought to be. Horses are incredibly sensitive to our balance, so just that ever-so-slight hint of a downward tilt towards the in the fine yellow line in the image below tells your horse you do not want them to move forward at all.

As the blue line moves behind the rider’s center of balance, the novice feels like they are just about to topple over onto the horse’s neck. Most people then quickly curl up and grab on to the reins for dear life so their upper body becomes at least as tense as their lower body. A kind horse usually slows down or even stops in response.
Novice, (and all to many intermediate) riders then resort to kicking their horse’s in the ribs, often with spurs, to get them to go. That is a totally counterproductive move. On the horse’s side of the equation, thumping the muscles of their ribs and abdomen makes their ‘core muscles’ tense up. Those muscles include some that are essential to pull their thighbone forward.
On the human side of the equation, our knees do not bend to the side, so we have to lift our legs away from our horse’s sides from the hip in order to kick. Besides that, most people cannot move their legs independently. One leg pulled away from the horse means both legs are busy lifting themselves instead of fine-tuning our balance.
Taking both your legs away from your horse’s sides makes it a whole lot harder to stay on if they should react by leaping forward. Plopping backwards onto your horse’s back after you startle them into jumping forward is the fastest way to teach them to ignore your legs. Spurring your horse bloody or shocking them with electric spurs to make them react in spite of your body telling them not to move is ignorant as well as inhumane (click here).
Below is how a rider trying to thump their horse in the ribs with one leg looks from the front. In real life, a person with all their weight on one foot also shifts every bone muscle and ligament from their tailbone to their atlas to keep their balance. On horse back, that means their weight is way off to one side.

Especially when novice riders try to use just one leg aid at a time, they easily become contortionists precariously balancing on one seat bone. That’s why riding instructors find themselves shouting ‘Heels Down’ and ‘Eyes Up’. And it is why novices fall off.
The difference between novice and advance rider’s seats was especially apparent during the walk. Novice riders showed ‘constantly activated patterns of muscle activity’. In layman’s terms, the novice riders were tense, riding on their horse not with them.
The solution is learning finesse in the saddle. This report concludes that their sensors detected four main muscular elements that differed between novice and advanced riders.
Advanced riders are able to adapt their balance to the horse’s movement
Advanced riders are able to choose when and how they shift their balance in the saddle.
Advanced riders are able to activate muscles in their limbs and their torso contra-laterally and independently
Advanced riders are able to coordinate those muscles, moderating how much they activate and/or relax any or all of those muscles.
The good news is that engaging in ‘sport specific exercises’ for twenty minutes three times a week resulted in ‘substantial adaptions’ in novice riders after only eight weeks. The researchers recommend riders practice ‘bilateral disassociation’ and ‘whole body muscular toning exercises’ with especial emphasis on ‘gravity awareness’.
But they do not give details of any exercises. When I wrote my series on schooling horses and riders, I insisted on offering exercises on the ground and the saddle to help riders first develop independent aids then learn how to coordinate them. I soon found out that offering people solutions to problems they have never imagined does not sell books.
Now that there is a scientific study that outlines the problems, perhaps people will start looking for solutions and decide to buy my books! I mean, who could resist exercises for riders developed by riders that build from work on the ground to work in the saddle that actually make a difference?