Flexibility in a fitness context is commonly measured using tests that assess the range of motion in joints and muscles. One widely used method is the sit-and-reach test, which evaluates lower back and hamstring flexibility. Other approaches include measuring joint angles through goniometers and assessing overall body flexibility through a series of dynamic stretches. Regular flexibility assessments can provide valuable insights into an individual's musculoskeletal health and are important for creating well-rounded fitness programs.