But what you need to know: In the first few applications the roles hurts a lot, probably because the first time is rolled over the total tense muscles (or you do the exercises wrong, careful body tension!). This pain go after several "treatments" but away of its own accord.
What you also need to know: When untrained person with back problems such relaxation training can be counterproductive without additional strengthening of the muscles! The back is held by the muscles and the only reason they are at all tense, is that the much frantically to weak muscles try to support the back. Dissolve now these tensions that may lead to the back is no longer supported enough and there is cramps in the back muscles, are desperately trying to prop up a (I had initially, very unpleasant). To a targeted strength training will not get you around, if you have back problems! This role is not a miracle cure!
But if you observe these points can safely access here. The back will thank you.
Also highly recommended for strength athletes, who have to fight against muscular problems.