Physical therapy, like any other discipline, has its share of dearly held beliefs. Perhaps none is stronger than the notion that static and dynamic postures are directly related to muscular strength.
This is not true. The following references and commentary from peer-reviewed literature support my contention that strength and posture are unrelated.
Relationships between lumbar lordosis, pelvic tilt and abdominal muscle performance Rothstein et.al. Physical Therapy vol. 67/No. 4 1987.
This is the classic by the man who now edits the APTA Journal. It showed for the first time (it hadn’t been studied before) that “lumbar lordosis, pelvic tilt, and abdominal muscle function during normal standing are not related.”
Relationship between performance of selected scapular muscles and scapular abduction in standing subjects DiVeta et.al. Physical Therapy Vol. 70, no. 8/August 1990.
This concludes: “The results indicate that no relationship exists between the position of the scapula in standing subjects and the muscular force by the middle trapezius and pectoralis minor muscles.”
My personal favorites are from David Levine, PhD. PT at UT Chattanooga. In a personal communication he writes: “In a study published in 1997 in Physiotherapy Theory and Practice, not only did we not find any correlation between muscle strength and posture pre-intervention, but we strengthened weak muscles (abdominals) for eight weeks (as well as prescribing full exercise programs intended to alter pelvic tilt and lumbar lordosis) and found that after an intensive eight week course of PT (3x/week supervised with home program bid), posture (pelvic tilt and lumbar lordosis) had not changed at all. We later studied these variables dynamically using specially designed rigs for the Vicon motion analysis system and again found no correlations between muscle strength and posture dynamically (walking).”
See The effect of abdominal muscle strengthening on pelvic tilt and lumbar lordosis Levine D, et al Physiotherapy Theory and Practice (1997) 13, 217-226.
See also Static and dynamic relationships between pelvic tilt, lumbar lordosis and abdominal muscle performance Levine D, et al Physical Therapy 76:s74; 1996.
As of this writing (March, 2000), the most recent study I can find on the subject is Lumbar Lordosis and Pelvic Inclination in Adults With Chronic Low Back Pain Youdas et al Physical Therapy vol. 80. no.3 March 2000
Its conclusion reads in part “…the magnitude of the lumbar lordosis and pelvic inclination in standing is not associated with the force production of the abdominal muscles.
I would be glad to include here any research to the contrary, but I haven’t been able to find any. If anybody knows of some, please contact me.
I recently spoke with the director of a PT program about this issue. She was unaware of the literature on the subject, and she told me that I needed to understand that it was their responsibility to teach what had always been accepted as the basic principles of physical therapy.
“Oh,” I said.