A couple MJR observations for guitarists

[Meedleyx10]

Still incorrect, as stated talk to your doctor or chiropractor. Lifting your legs in seated position uses your glutes, not your back muscles.

If you read this article, it talks about how lifting your legs off the ground REMOVES back strain.
http://healthguide.howstuffworks.com/back-pain-low-dictionary.htm

Try again .....

"Use a stool under your feet while sitting so that your knees are higher than your hips. "

Quoted from your link...keyword: feet...plural...not applicable to what we're talking about here. It's more about where your legs are positioned in relation to each other, and the alignment/misalignment issues that can cause.

Talk to any serious classical guitarist, teacher, doctor, chiropractor, or just use google. This is all fairly common knowledge amongst classical players and discussions on it can be found on pretty much any classical guitar forum...a brief google search will show you plenty.

 

[progmetaldan]

In that sense, classical position is also bad for your back. You end up either hunched over or with your left leg elevated, both of which can/will cause back problems. The better solution is to just keep it strapped on (assuming you wear your guitar high enough for it to be in a good position when you are sitting with both feet on the ground) or, if you are playing a classical guitar, using one of those suction-cup mounted leg stands that is affixed to the bottom of the guitar and props your guitar up into position with both feet n the ground so you're not having to hunch over or prop your leg.

Yeah, those 'Ergoplay' thigh-rests really helped my back, having the one leg raised means your back is slightly twisted, whereas both feet on the ground keeps your spine straight, but the thigh-rest allows you to angle the guitar into the proper position and height. With electric, my strap is high enough that it doesn't matter whether I'm sitting or standing, its still in the same position, high and with the neck angled up...