Temporal Associations Between Pain-Related Factors and Abnormal Muscle Activities in a Patient with Chronic Low Back Pain: A Cross-Lag Correlation Analysis of a Single Case

Figures & data

Figure 1 The standing, trunk flexion and re-extension task.

Figure 2 The approximate position of the EMG grid. The EMG electrode grid was placed 3 cm lateral to the lumbar spinous process on the bilateral erector spinae.

Table 1 Patient Characteristics

	Number of Observations
	1st	2nd	3rd	4th	5th	6th	7th	8th	9th
SFMPQ-2-total	71	31	35	32	29	32	16	20	28
FreBAQ	28	12	5	11	7	6	0	1	5
OMSQ-12-psychological factor	26	12	15	8	11	11	10	12	13
PSFS	8	4	6	6	4	5	4	6	6
FRR	4.11	3.51	4.52	3.78	3.99	3.58	4.85	4.67	4.49
RMS (full flexion phase)	0.93	0.91	0.96	0.94	0.92	0.95	0.83	0.89	0.95
RMS (extension phase)	1.01	0.97	1.02	1.01	1.00	1.00	0.91	0.96	1.01

Abbreviations: SFMPQ-2, Short-Form McGill Pain Questionnaire-2; PSFS, Patient-Specific Functional Scale; FreBAQ, Fremantle Back Awareness Questionnaire; OMSQ-12, Örebro Musculoskeletal Screening Questionnaire-12; FRR, flexion relaxation ratio; RMS, root mean square.

Table 2 Cross-Correlations at Zero Lag Indicating the Level of Cross-Sectional Associations Over Time Between Pain-Related Factors and Muscle Activity

	SFMPQ-2-Total	FreBAQ	OMSQ-12-Psychological Factor	PSFS	FRR	RMS (Full Flexion Phase)	RMS (Extension Phase)
SFMPQ-2-total	1
FreBAQ	0.70*	1
OMSQ-12-psychological factor	0.42	0.19	1
PSFS	0.51	0.18	0.57	1
FRR	−0.48	−0.78**	0.16	0.21	1
RMS (full flexion phase)	0.44	0.16	0.37	0.47	−0.22	1
RMS (extension phase)	0.75*	0.34	0.57*	0.67*	−0.13	0.91**	1

Note: *p < 0.05, **p < 0.01.

Abbreviations: SFMPQ-2, Short-Form McGill Pain Questionnaire-2; PSFS, Patient-Specific Functional Scale; FreBAQ, Fremantle Back Awareness Questionnaire; OMSQ-12, Örebro Musculoskeletal Screening Questionnaire-12; FRR, flexion relaxation ratio; RMS, root mean square.

Figure 3 The correlation coefficients between each of the pain-related factors and muscle activity at zero lag.

Notes: Color-filled markers: indicate correlations that reached statistical significance. Unfilled markers: indicate correlations that not reached statistical significance. Circle markers: indicate correlations between the SFMPQ-2 and muscle activity. Triangle markers: indicate correlations between the PSFS and muscle activity. Square markers: indicate correlations between the OMSQ-12-psychological factor and muscle activity. Rhombus markers: indicate correlations between the FreBAQ and muscle activity. Abbreviations: SFMPQ-2, Short-Form McGill Pain Questionnaire-2; PSFS, Patient-Specific Functional Scale; FreBAQ, Fremantle Back Awareness Questionnaire; OMSQ-12, Örebro Musculoskeletal Screening Questionnaire-12; FRR, flexion relaxation ratio; RMS, root mean square.