Analysis of the relationship between the transversus abdominis and lower back pain using an ultrasound.
Meng Ge, Ko Onoda, Hitoshi Maruyama and 5 others
PMID 34776620WHAT IT FOUND
People with chronic low back pain had thinner abdominal muscles when contracting them with their pelvic floor compared to pain-free people.
However, the test was poor at identifying patients, missing half of them. This measurement is not yet a reliable diagnostic tool.
Key findings
01The thickness of the transverse abdominis muscle was significantly lower in the chronic low back pain group (5.4 mm) than in the non-pain group (6.3 mm) during simultaneous contraction with the pelvic floor.
02Using a cut-off value of 5.45 mm for this muscle thickness, the test correctly identified only 51% of people with chronic low back pain, though it correctly ruled out 81% of pain-free people.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study design cannot prove that thin muscles cause pain; it only shows an association. The diagnostic test had low sensitivity (51%), meaning it failed to identify half of the participants with chronic low back pain. The sample size was small (33 patients with pain), which reduces the reliability of the findings. The study did not measure pelvic floor muscle contraction alone, so it is unclear if the pain group's weakness is specific to the combined movement or if the pelvic floor itself is impaired.
Declared interests
The authors declared no conflicts of interest and stated the study received no financial support.
The easy way to misread this
Do not conclude that a thinner abdominal muscle causes chronic low back pain. This was a cross-sectional study showing an association, not a cause-and-effect relationship. Furthermore, do not use this ultrasound measurement to rule out pain in a patient, as the test missed 51% of the confirmed cases.