(Edit note: in the article I linked, what I call "draw reins" she calls "running reins" - just to clarify that distinction in phrases)
When I started training with my current trainer, Audrey, I was pretty anti-gadgets. Not so much anti-the gadgets themselves but I had seen what could have happen if they're used incorrectly. The exception is side reins, my old trainer, Karen had shown me how to use side reins when lunging to help a horse find the most beneficial way to use their body. She also taught me what not to do with them, and there is quite a bit of "what not to do with them" that it seemed like a lot of otherwise well educated people were not aware of.
Needless to say, I was hesitant when Audrey suggested we try draw reins with my Fjord, Mr. Geir. I was especially leery of their use because of the famous, nasty training method called Rollkur lots of folks have used as a "short cut" to get quick results for what is known as a "false frame". Audrey knew I was leery of gadgets and acknowledged that and then explained what the point of using drawreins with Mr. Geir would be. In his case, he has a habit of throwing his head up and back in order to avoid contact with the bit and when he does that his back hollows and he pulls himself along with his front end. Audrey wanted to draw reins to keep him from being able to throw his head back.
So, we've been using them the last few rides. For one thing, they're not very tight and I hold them with my regular reins just like I would when riding Audrey's horse with a double bridle. Watching Audrey ride him with the draw reins I was happy to see that they did not pull his head down, but they did keep him from whipping his head up and back. And when I'm riding him there are more times than not now that I feel him round his back and use impulsion from his hind end, which feels really cool.
I thought this article explained well the roll that "gadgets" can play in training.
Just like the other tools for communication in riding, side reins, draw reins, dressage whips, spurs, etc. can either be training aids, when used by someone who truly understand equine anatomy and kineseology. Or they can be painful and detrimental to the horse when used incorrectly. I had the same experience with pilates, I went to a mat class once at a gym and I tried to do the exercises correctly but no was working directly with me - the instructor was up at the front of the room several rows away from me. Afterward my neck was strained and my lower back was wrenched. I decided I hated pilates, until I tried again, this time with a one-on-one class with an instructor guiding me through the exercises on a reformer machine. The second time it was still very hard work, and my core muscles were sore, but nothing was strained or wrenched and over time it has been very beneficial to the way I ride horses and use my body on an everyday basis. Just an FYI for locals, that was Shelly Gossard in Seattle who is an excellent pilates instructor. I worked with her until I moved to the Eastside and started working with Beth Glosten, who I also highly recommend.
So, Mr. Geir was out being worked with draw reins today during his training session with Audrey. And I'm sure someone out there will be horrified by that. But I feel like I'm giving him the opportunities I've had with pilates, when I've been in a class with Beth Glosten and she has stopped to help me by tapping my belly where I'm supposed to engage the muscle and touching my shoulder to stabilize it so I don't use my neck/shoulders to compensate, it is very similar to what Audrey does with Geir with taps and pulls and pushes to say "use this muscle instead - there you go - see how it's easier to move now?" And Geir has that same excited "I did it! Did you see what I can do?!" glow about him that I have after making it through a pilates class.