Investigation on the effectiveness of abdominal hollowing home-exercises using a portable ultrasound: Randomized controlled trial.

We used a 3-arm randomized control trial to investigate whether abdominal hollowing (AH) home exercise using pocket-sized ultrasonography (US)-miruco (AH with miruco group)-was more effective than conventional AH home exercise using abdominal palpation and or also a wait-and-see approach (control group) to improve isolated control of the transversus abdominis (TrA) muscle during AH. We randomized 60 participants with low back pain into the three groups equally. Primary outcome measures for the US group were percentage of change in TrA thickness and excursion of the edge of the TrA fascia during AH when the thickness of the internal or external oblique muscles increased. Score on the Oswestry Disability Index (ODI) was a secondary outcome measure. The intervention period was 1 week, followed by 1 week without intervention. As a result, we found no statistically significant interaction effect (P > .05) in changes of the primary outcome measures from baseline for each follow-up period. The AH with miruco group had a statistically lower ODI (P = .036) than did the control group after the intervention. Results indicate a limited benefit for use of the miruco in AH home exercise to improve isolated control of the TrA muscle during AH.