Examination was performed simultaneously by two researchers (physiotherapists with 5 years of practice). The first researcher (R1) conducted all of the tests and measurements by use of AMI Digital Inclinometer (OPIW, Poland) with accuracy of 1.0° and a flexible tape measure with accuracy of 0.5cm. The second researcher (R2) controlled visually and with palpation the subjects’ position during examination, namely stable position of the pelvis and/or flat position of the lumbar spine.