Abstract: A device for measuring the angle of curvature of the lumbar spine of a subject includes a flexible, elongate member disposed parallel, and fixed at one point, to the lumbar back of the subject. A second point of the elongate member displaces when the subject bends forwardly or rearwardly from an initial position. A displacement sensor, coupled to the elongate member, determines displacement of the second point when the subject bends forwardly or rearwardly. The device also includes AF and pelvic inclinometers for respectively measuring the rotational angles of the thorax and pelvis of the subject as well as a rotary potentiometer for measuring the twisting angle of the trunk of the subject. The device can be used as a field device for providing such measurements while the subject carries on normal physical activity.