Table 1.
Anthropometrics and back pain status of healthy controls (H;Hmatched) and back pain symptomatic subjects (BPP).
Fig 1.
A. 12-lead EMG-trunk-setup. (Mm rec. abd. (RA), obl. ext. abd. (EO), obl. int. abd (IO) of left and right side) and 6 dorsal (Mm erec. spinae thoracic (T9; UES)/lumbar (L3; LES), latis. dorsi (LD) of left and right side; VR: RA, EO, IO of right side; VL: RA, EO, IO of left side; DR: UES, LES, LD of right side; DL: UES, LES, LD of left side). B. Kinematic trunk model (Müller et al. 2015).
Fig 2.
Exemplarily EMG signal for the 6 right-sided trunk muscles (raw signal of 1 perturbation for one subject) including visualization of EMG outcome measures (EMG-RMS, TON, TMAX).
Fig 3.
Group comparison of the LTA segment motion in (a) flexion, (b) lateral flexion and (c) rotation: Comparison of unperturbed and perturbed step in H and BPP (group mean ± SD). negative values represent flexion, left-sided rotation and left-sided lateral flexion for all 3 segments. positive values represent extension, right-sided rotation and right-sided lateral flexion.
Fig 4.
Case comparison of the LTA segment motion in (a) flexion, (b) lateral flexion and (c) rotation: Comparison of unperturbed and perturbed step in one healthy and back pain patient (individual mean ± SD of 15 perturbed and unperturbed steps). negative values represent flexion, left-sided rotation and left-sided lateral flexion for all 3 segments. positive values represent extension, right-sided rotation and right-sided lateral flexion.
Fig 5.
Neuromuscular reflex activity (EMG-RMS; %) of the four trunk areas during stumbling in healthy (H; Hmatched) and back pain symptomatic subjects (BPP).
Legend: VR/VL: mean EMG-RMS of RA, EO, IO ri/le; DR/DL: mean EMG-RMS of LD, UES, LES ri/le).
Fig 6.
Polarplot of neuromuscular response time of 12 trunk muscles to perturbation.
(A) onset of muscle activity (TON; ms) after perturbation. (B) time to maximum activity (TMAX; ms) after perturbation.* significant differences between H and BPP (p<0.025); # significant differences between Hmatched and BPP (p<0.025).
Table 2.
Neuromuscular reflex response (TON; TMAX; [ms]) for all muscles for H, Hmatched and BPP.
Table 3.
Total motion amplitude (ROM) during normal, unperturbed step [°] and perturbed step normalized to unperturbed step [%] for the whole stride cycle and the subsequent 200ms after perturbation for all three segments in all planes (mean ± SD).
Fig 7.
3-D trunk kinematics during stumbling (mean trunk angle (Amean; [°]; subsequent 200ms after perturbation) including mean ± 95%-confidence interval for (A) extension-flexion and (B) lateral flexion. * significant differences between H and BPP (p<0.025); # significant differences between Hmatched and BPP (p<0.025). negative values represent flexion, left-sided rotation and left-sided lateral flexion for all 3 segments. positive values represent extension, right-sided rotation and right-sided lateral flexion.
Table 4.
Trunk posture (Amean [°]) during normal, unperturbed step and perturbed step for the whole stride cycle and the subsequent 200ms after perturbation for all three segments in all planes (mean ± SD).