Why outside and not inside?

I Audited a Dressage Clinic, taught by Sarah Hughes - she is at Prix Saint George and trains under an Olympic Rider *cannot remember his name for the life of me*

In her clinic, she stressed time and time again at how many riders use the inside rein for turning, when they shouldn't be, they should be using the outside rein. And it was really neat watching her get on one of her Clinitians horses, a horse she never rode before - to show what she meant.

She used the outside rein with the inside rein dropped, and used her seat and legs as well and was able to do circles, and serpentines and half passes.

Eye opening.
Absolutely correct. Inside Leg into Outside Rein.

^^so as it turns out I was doing it right all along. lol. maybe I just have dyslexic memory/hearing.....

I'm not getting what you mean by "inside rein" when you say you neck rein? "Inside rein" would imply that you are direct reining. Unless I'm missing something?

The use of the outside leg should guide your horse's shoulder, while your inside leg asks the horse to bend.

I also would like to see the physics behind the theory. Is it just what someone found works best or is there actual science behind it? Anyone know where it originated?

It's basically that principle that MIeventer explained there, except in English it would still be standard to have a two hand hold on the reins. In Western its standard to hold the reins with one hand. So the "inside rein" is still used its just kind of passive? I think thats the best way to describe it.

I was just clearing that up so that people didn't assume I was direct reining.

I suppose that makes sense, but since it's a passive aid that simply happens because of another aid (i.e. outside rein put laid on neck, inside rein drops/opens) then it seems silly to me to teach it that way. I teach western lessons and I never use the phrase "inside rein" because it's an aid that doesn't really exist - the rider should never directly affect in the inside rein...

The way that I ride fits Wild_Spot's explination to a T. Of course though I ride western and most of the time we want the horses body straight and they should swing the front end around while keeping the back end stationary. I neck rein so when I want to turn left, I apply the outside rein which tells the horse to move his shoulders and outside leg, which blocks the hindquarters and ribcage from swinging out and destroying the momentum of the turn. But of course, I don't ride using mostly seat and leg cues. I ride with mostly rein cues and some legs for more complex manouvers or to reinforce the cue given by the rein.

too lazy to see if anyone else says this so plainly, but I think of it as (if you're turning it to the right) you're pulling him to the right in the front right and pushing him to the right in a position further back-on the opposite side. if that makes sense.
not that you should literally be pushing or pulling your horse....but..xD

^^ i'm not asking how, lol. My TB responds well to my cues as wierd as they are, but we've all had to throw out the book as far as training him to any conventional discipline goes. But thats an OTTB for you. I think the way I explained it in my earlier post was a little off though, the pressure from my inside leg doesn't propel his butt, that's just how I see it when I think of it....he does bend around my leg (although not as good going to the left as to the right), I think the heel pressure I use just kind of reminds him to turn instead of drift sideways like he does when I just use the rein cue.

MyBoyPuck really got the point of the whole post, being where did this bit of knowledge come from?

well I did mean why and not how xD maybe there's something else I'm missing?