Which of the following describes the characteristics of flat back posture?

The characteristics of flat back posture are best defined by having a flat lumbar and lower thoracic spine along with a posterior pelvic tilt. In this posture, the natural curve of the lumbar spine is diminished, leading to a more straightened appearance. This flattened curve can impact the way that the pelvis is positioned; a posterior pelvic tilt often accompanies this posture, where the pelvis rolls backward, decreasing the natural lumbar lordosis.

Individuals exhibiting flat back posture may experience discomfort due to the alteration in the spine's natural curve, which can affect overall alignment and the biomechanics of movement. By understanding this posture's specific characteristics, practitioners and instructors can better address alignment and muscle imbalances during Reformer Pilates sessions, helping clients improve their posture and reduce potential strain on their bodies.