Physical inactivity is associated with narrower lumbar intervertebral discs, high fat content of paraspinal muscles and low back pain and disability

Table 1 Participant characteristics

	Inactive	Moderately active	Active	P
	(0 days)	(1 to 8 days)	(9 to 14 days)
	N = 15	N = 38	N = 19
Age (years) ^*	47.2 (1.3)	45.1 (0.7)	46.5 (1.5)	0.29
Gender (n, % female) ^**	13 (86.7)	26 (68.4)	10 (52.6)	0.11
Weight (kg) ^*	99.0 (3.6)	96.5 (2.1)	84.4 (4.3)	0.02
Height (m) ^*	1.67 (0.01)	1.67 (0.01)	1.70 (0.02)	0.21
BMI (kgm ⁻² ) ^*	35.7 (1.3)	34.8 (0.8)	29.3 (1.5)	0.002
Intervertebral disc height (L1 to S1) (mm) ^*
Average	10.2 (4.1)	10.6 (2.6)	11.8 (3.6)	0.01
Paraspinal muscle properties
CSA (cm ² ) ^*
Multifidus	6.9 (0.4)	6.9 (0.3)	7.2 (0.4)	0.76
Erector spinae	19.7 (1.1)	20.5 (0.7)	21.7 (1.0)	0.41
High fat content, n (%) ^**
Multifidus	9 (60.0)	13 (34.2)	3 (15.8)	0.03
Erector spinae	5 (33.3)	7 (18.4)	1 (5.3)	0.11
Chronic low back pain grade, n (%) ^***
Pain free	3 (20.0)	6 (15.8)	5 (26.3)	0.049
Low disability, low intensity	5 (33.3)	24 (63.2)	14 (73.7)
Low disability, high intensity	4 (26.7)	1 (2.6)	0 (0.0)
High disability, moderately limiting	1 (6.7)	4 (10.5)	0 (0.0)
High disability, severely limiting	2 (13.3)	3 (7.9)	0 (0.0)
High pain/disability, n (%) ^***	7 (46.7)	8 (21.1)	0 (0.0)	0.004

Results displayed as mean (standard error of the mean) unless otherwise stated. ^* P values determined from pairwise comparison among the estimated marginal means; ^** P values determined from chi-squared test; ^*** P values determined from Fisher’s exact test. BMI, body mass index; CSA, cross-sectional area.

ISSN: 1478-6362