Intra-tester reproducibility of pressure biofeedback in measurement of transversus abdominis function

Strength, co-ordination and timing of transversus abdominis muscle contraction may be important in stabilizing the low back, and contraction of this particular abdominal muscle may be one factor capable of preventing and reducing low back pain in sport and in activities of daily living. The function and strength of the transversus abdominis muscle is difficult to measure. The pressure biofeedback unit (PBU) is a device designed to teach and measure transversus abdominis muscle function. The purpose of the present study was to evaluate intra-tester reproducibility of the PBU.

The study used a test-retest design. Fifteen healthy subjects (mean age 22.2 years, range 19-28 years) with no history of low back pain participated in the study. After two sessions of practising transversus abdominis muscle contraction, its function was measured in prone position with the PBU device placed over the transversus abdominis muscle. Subjects were instructed to draw in the abdominal wall (for example, lifting it away from the device) after a standardized procedure. Two tests were conducted on two different days, with a seven-day interval in between.

Coefficient of variance (CV) was 21.0% and the standard deviation (SD) of delta was 1.59.

The use of the PBU should be improved for scientific purposes. However, the device may have a role in providing biofeedback to assist in the instruction of correct transversus abdominis muscle contraction.