Joint range of motion (ROM) varies by movement, which is why a battery of flexibility assessments is recommended to identify deficiencies. Direct measurement with tools such as a goniometer, inclinometer, or flexometer provides quantifiable data and established norms for each joint action. Goniometer use requires anatomical knowledge and precision; errors most often come from misaligning the axis or bony landmarks. When performed correctly, it shows high validity compared to imaging methods like