How do we know that the strength measurement of the MedX Lumbar Extensor Machine is reliable?

The MedX Lumbar Extensor Machine is
the first and only machine capable of isolating the lumbar
extensor muscles, and producing an objective measurement of
a patient’s lower back strength and range of motion.

The research…

A study evaluated the reliability
and variability of repeated measures of isometric lumbar
extension strength made at different joint angles
in 56 men and 80 women. The data indicated that repeated
measures of isometric lumbar extension strength are highly
reliable and can be used for the quantification of isometric
lumbar extension strength through a range of motion.

Graves et al., SPINE 1989 – COPY AVAILABLE

A 1990 Study found that the MedX Lumbar Extensor Machine
provides a safe, valid and reliable tool with which to measure
changes in strength and range of motion in patients with
a variety of lumbar disorders (e.g. lumbar strain, herniated
discs, degenerated discs, spondylolisthesis, and others)

Russell et al. North American Spine Society Annual Meeting,
1990

See also
Pollock et al, Am J Sports Med. 1989
Risch et al., SPINE 1993

N.B. Isometric Testing using the MedX Lumbar Extensor Machine
differs markedly from dynamic testing on "isokinetic"
machines which is a process fraught with potential inaccuracies
due to:

• Acceleration
  / deceleration during test movement
• Failure
  to spot variation in strength as angles of flexion
• Effect
  of gravity / torso mass