Comparison between bracing and hollowing trunk exercise with a focus on the change in T2 values obtained by magnetic resonance imaging

The purpose of this study was to compare the muscle activity of Bracing and Hollowing trunk exercises by means of T2 values using MRI. Subjects were 19 healthy adult males, of whom 10 (with mean height ± SD: 172.3 ± 4.7 cm, mean weight ± SD: 64.3 ± 5.4 kg, mean age ± SD 21.5 ± 1.9 years) performed hollowing and 9 (with mean height ± SD: 171.3 ± 2.1 cm, mean weight ± SD: 68.5 ± 11.7 kg, mean age ± SD: 23.0 ± 2.6 years) performed bracing. They were assessed using MRI. The imaging was completed using Osirix software, which measured T2 values from the transversus abdominis (TrA), internal oblique (IO), external oblique (EO), and multifidus (MF) muscles. Subsequently, T2 values recorded before the exercise were compared with those recorded after the exercise to evaluate the extent of change effected by exercise on the muscles. MRI T2 values indicated that the TrA and IO regions were activated to a significantly greater degree after bracing. No significant changes occurred in any muscle before and after hollowing. It was determined that the activity of the deeper trunk muscles was higher in bracing than in hollowing on comparing the T2 values obtained in the MRI.