A reliability study in 24 participants, 12 asymptomatic and 12 with chronic non-specific low back pain, found intra-rater ICCs of 0.86-0.99 and inter-rater ICCs of 0.86-0.99 for transversus abdominis and gluteus medius thickness in standing tasks, with SEM and MDC estimates. Reliability does not establish diagnostic validity or treatment benefit.
Key findings
- Intra-rater ICCs were 0.86-0.98 for TrA and 0.90-0.99 for GM; inter-rater ICCs were 0.86-0.95 and 0.91-0.99. SEM ranged 0.12-0.39 mm for TrA and 0.63-1.83 mm for GM; MDC ranged 0.35-1.09 mm and 1.75-5.08 mm.
Why this matters globally
Reliability and MDC estimates help design studies and rehabilitation monitoring by preventing sub-error changes from being misread as real change.
Thai researcher contribution
Physical-therapy, radiologic-technology, anatomy and ICARE Centre teams at Chiang Mai University conducted the protocol and rater assessment.
Limitations to consider
Twenty-four participants are few, and ICC can be high from between-person variability despite meaningful absolute error. Rater expertise, between-day reliability and MRI validity are unclear. Thickness is not activation, strength or a cause of pain.