Measuring transversus abdominis activity using pressure biofeedback unit-A technical report.

Background and purpose: Pressure biofeedback is a tool that can detect the movement of a structure and may be used as an indicator of muscle function. It's widely used to measure the transversus abdominis (TrA) muscle activity. Pressure biofeedback (PBU) monitors the abdominal wall movement by measuring the pressure change during abdominal hollowing and can indirectly evaluate the TrA muscle function, which is considered as a valuable tool. The evaluation of the training of core muscles, including the transversus abdominis, requires a reliable outcome. Various methods using different positions are used to evaluate the transversus abdominis muscle function. However, it is noted that a standard way of evaluation and training still needs to be improved in research and clinical practice. This technical report discusses the optimal position and technique to measure the TrA muscle activity using PBU, with discussions on the merits and demerits of the body positions.

Methods: The technical report is presented with a literature review of the PBU measurement of TrA and through observation in the clinical practice. The evaluation methods of TrA, including the position to activate and isolate, are discussed in detail.

Results: Training core muscles does not imply TrA activation, and evaluating isolated TrA and multifidus is essential before intervention. The abdominal drawing-in maneuver effectively activates TrA in various evaluation positions of the body, but when using PBUs, it would be valid in a prone position.

Discussion: Different body positions are practiced to train TrA and core muscles using PBU, commonly adopted by practice are in supine. It's noted that most of the studies lack in establishing the effectiveness of the position in evaluating the TrA muscle activity using PBU. The need for insight into an appropriate technique for evaluating TrA activity is addressed in this technical report. This report presents key points on the complete technique and concludes that the prone position is superior to other positions and recommended for measuring and recording the TrA activity using a PBU.