“…Standing measures of muscle function of abdominal-muscle thickness in gravity-loaded positions have been observed to be both reproducible 33 and reliable. 26,27,32,33 Since the PAR is a ratio of the TrA thickness in comparison with the entire lateral wall between contracted and resting states, any increase in PAR could indicate an increased ability to activate the TrA independently from the other abdominal muscles. The current findings indicate that individuals with a history of LBP can increase TrA PAR in a standing position after a single bout of exercise, and the addition of biofeedback may have a greater effect on TrA PAR (Table 5).…”