Would you lunge (or have you lunged) in a running martingale? Why or why not? Something I saw recently and am wondering, as I've never lunged with a martingale on...
No, because I don't ride in one. Wouldn't use one to lunge unless for a quick spin before getting on - effect wouldn't be the same as if you were riding. Why are you asking?!
Is it part of your riding tack or are you thinking of putting it on the side reins?
If just part of riding tack then take reins out of rings and tie martingale rins to neck strap/breast plate, secure reins around horses neck so they don't drop and tangle with legs. Easiest way is to have reins on neck, twist the two together and feed throat lash through, do up throat lash.
Attaching to the side reins is definately not a good idea.
OK, to reiterate, this was something I saw being done, NOT something I have done, or will be doing. Personally, I lunge in either side reins or the kavalkade lunging rein.