Fig. 5.

Stratifying subjects into three groups using subject reported pain severity (VAS) shows a shift in multifidus FI between groups, focused near the peak of the FI distribution in the deep multifidus Left: The location of the multifidus and erector spinae global peak in FI consistently falls in the deep region of the muscle, whereas there is more variability in peak location in the psoas. Only the multifidus global peak magnitude is significantly different between patients and controls. Right: SPM analysis shows significant differences in FI distribution at the global peak in multifidus FI between patients with high VAS and controls (bottom). Patients with low VAS scores were not different from controls, showing a pain-associated shift in FI localized at the deep multifidus