Table 3.

Center of pressure displacements of people with LBP and healthy subjects

Condition	LBP group (n = 16) Mean ± SD (m)	Control group (n = 16) Mean ± SD (m)	F value	p value
Control
PS (rms)	0.079 ± 0.039	0.071 ± 0.040	1.67	NS
TS (mean)	−0.117 ± 0.051	−0.093 ± 0.015	3.79	NS
MF (mean)	0.014 ± 0.016	0.036 ± 0.022	3.47	0.01
PS F (rms)	0.123 ± 0.033	0.081 ± 0.025	6.64	0.02
TS F (mean)	−0.103 ± 0.036	−0.056 ± 0.019	8.86	0.001
MF F (mean)	0.015 ± 0.010	0.054 ± 0.022	4.24	0.0002
Fatigued
PS (rms)	0.077 ± 0.038	0.082 ± 0.024	1.67	NS
TS (mean)	−0.100 ± 0.035	−0.100 ± 0.015	3.79	NS
MF (mean)	0.014 ± 0.006	0.029 ± 0.018	3.47	NS
PS F (rms)	0.136 ± 0.038	0.131 ± 0.037	6.64	NS
TS F (mean)	−0.106 ± 0.026	−0.096 ± 0.021	8.86	NS
MF F (mean)	0.015 ± 0.008	0.039 ± 0.015	4.24	0.003

F values represent the interaction effects and p values the Tukey post hoc tests

SD standard deviation; PS postural stability trial; rms root mean square; TS triceps surae muscles vibration; MF lumbar multifidus muscle vibration; F while standing on a “foam” support; LBP low back pain; NS not significant