The influence of fatigue and chronic low back pain on muscle recruitment patterns following an unexpected external perturbation

Table 3 Comparison between healthy and chronic low back pain subjects

	Principal effect	gl	F	Sig (p)	pŋ2	Power	Post hoc/Simple factor
Start 1st Burst	Group	47(1)	3.834	0.056	0.075	0.483
	Muscle		58.069	≤0.001	0.553	1.000	BB < IO < SE,RM,LM,EO
	Interaction		0.555	0.686	0.012	0.179
	Group mean difference (95% CI) = 8% (−17, 0.0) for start 1rst Burst
Start 2nd Burst	Group	34(1)	0.270	0.607	0.008	0.080
	Muscle		5.250	0.002	0.134	0.933	BB,EO > SE,RM,LM
	Interaction		0.565	0.651	0.016	0.168
	Group mean difference (95% CI) = 4% (−13, 22) for start 2nd Burst
Duration 1st Burst	Group	47(1)	1.038	0.314	0.022	0.170
	Muscle		58.160	≤0.001	0.553	1.000	BB > EO,IO > SE > LM
	Interaction		1.009	0.378	0.021	0.240	RM < BB > EO,IO
	Group mean difference (95% CI) = 11% (−11, 33) for duration 1st Burst
Duration 2nd Burst	Group	34(1)	0.010	0.919	0.000	0.051
	Muscle		33.709	≤0.001	0.498	1.000	BB,IO > EO > SE,RM,LM
	Interaction		2.408	0.089	0.066	0.508
	Group mean difference (95% CI) = 0% (−6, 5) for duration 2nd Burst
Num Bursts post impact	Group	47(1)	0.271	0.605	0.006	0.080
	Muscle		1.596	0.181	0.033	0.469
	Interaction		1.596	0.181	0.033	0.469
	Group mean difference (95% CI) = 0.56% (−0.16, 0.27) for Num Bursts post impact
Post/Pre Ratio	Group	47(1)	0.976	0.328	0.020	0.162
	Muscle		39.166	0.000	0.455	1.000	BB > IO > EO > RM,LM LM < SE < BB > IO
	Interaction		0.425	0.618	0.009	0.111
	Group mean difference (95% CI) = 0.22% (−0.67, 0.22) for Post/Pre Ratio
Co-co post impact	Group	48(1)	1.587	0.214	0.032	0.235
	Muscle		71.833	≤0.001	0.599	1.000	SE&EO < SE&IO < EO&IO
	Interaction		0.554	0.499	0.011	0.120
	Group mean difference (95% CI)= 15.19% (-9.05, 39.43) for co-co post impact

Significant ANOVA results corresponding to the comparisons between healthy subjects and those with chronic low back pain (group factor) and between muscles (muscle factor) for variables describing the timing and variables describing the amount of muscle activity post impact. Num bursts post impact number of bursts following the impact, Post/Pre Ratio ratio of root mean square of the post impact EMG signal amplitude and pre impact EMG signal amplitude, Co-co post impact co-contraction levels after the impact, BB biceps brachii, SE thoracic spinal erector, RM right multifidus, LM left multifidus, EO external oblique, IO internal oblique

ISSN: 1471-2474