Links explaining the correct use of side reins?

"Cross training your horse" by Jane Savoie for any discipline. http://www.artofriding.com/articles/lungeing.html Hope these help! I'll add more if I remember them! Do be careful with them, it can be a very useful aid, but very dangerous on the wrong horse or used in the wrong way.

you might want to reconsider. I know for a fact that using side reins can make a horse heavier and duller to the bit pressure..simply because there is NO real reward (release) for them to respond to it. basically all side reins do is keep the horse's head in a certain position, whether the horse likes it or not, and he learns to just keep his head there....and lean on the reins when his neck gets tired. he's going to lean on the reins and he's going to get heavy. I've seen this in person....at a TOP European barn owned and operated by a trainer who is famous in France for his use of classical dressage....this guy uses nothing but side reins for ground work and his horses....yes, they "collect" and yes they "go on the bit" BUT they have back problems and they are heavy on the reins until you make them get into that "collected" frame. They're like robots....they get in the frame and move as you wish....but there's no real softness and they aren't happy at all (they hate seeing the saddle coming their way)....they hate getting out of their stalls to go be lunged in side reins.... rethink this. there are better ways for the horse....to get true softness.

Usually your english riding and natural horsemanship sites will provide more information to this effect than western ones. Be careful with your use of them, though. Inexperience use of these can cause muscles to form incorrectly and pain in the neck/spine/back and gait issues. Make sure to read up A LOT before you go out and apply what you have "learned".