<qa>  What is the main reason for using complementary or alternative medical therapies?Back problems are among the most prevalent conditions affecting adults and are a leading reason for using complementary or alternative medical CAM therapies. Despite the common use of CAM therapies for back pain, little is known about how they compare with conventional treatments. This study will lay the groundwork for a full-scale trial that compares yoga with conventional exercise and usual care for chronic low back pain. 