Comparison of the Pressure Biofeedback Unit and Real-Time Ultrasound Imaging as Feedback Tools to Contract the Transversus Abdominis Muscle: A Randomized Controlled Trial in Healthy Older Adults

Background and Purpose: The transversus abdominis (TrA) is a key muscle for lumbar stabilization and is often retrained in physical therapy. Feedback tools, such as the pressure biofeedback unit (PBU) and rehabilitative ultrasound imaging (RUSI), are frequently used by physical therapists to train their patients and improve their patients' ability to contract this muscle. However, the effect of these tools in rehabilitating the TrA in older adults remains to be demonstrated, as is their efficiency in transferring the skill of recruiting the TrA from a supine position to a standing position. The objective of the study was to compare the immediate effectiveness of the PBU and RUSI to reeducate the TrA muscle in a population of asymptomatic older adults (without pain). Methods: Forty participants were randomized into 2 groups (RUSI or PBU). The intervention included a training session involving 15 TrA contractions held for 10 seconds with the corresponding feedback device. The dependent variable, TrA thickness (a muscle activation indicator), was measured using ultrasound images before and after the intervention in a supine and standing position. Nonparametric analyses were used for inter- and intragroup comparisons. Results and Discussion: The results showed no between-group differences in TrA activation ratio (AR) in the supine or standing position (supine AR: TrA RUSI thickness change P = .53 vs PBU thickness change P = .73, comparison between groups P = .51; standing AR: TrA RUSI thickness change P = .003 vs PBU thickness change P = .10; comparison between groups P = .61). However, the change in TrA thickness compared to the other abdominal wall muscles in a standing position was significantly less post-intervention for the RUSI group only (RUSI P = .006 vs PBU P = .72). Both groups remained similar post-intervention for this outcome (P = .20). Conclusions: Neither the RUSI nor the PBU seems to have the desired effect on the activation of TrA in asymptomatic older adults.