Some physicians, physiotherapists and nurses use or even suggest unstable shoes in cases of low back pain. No studies on the real effects of these shoes on low back pain in health care professions have been carried out and therefore as yet there is no real evidence of their effectiveness. Thus the investigators assume that wearing unstable shoes over a period of six weeks could reduce low back pain and functional disability due to the changes of the gait and posture and may increase the quality of life.