Is there a U-shaped relationship between physical activity in leisure time and risk of chronic low back pain? A follow-up in the HUNT Study

Table 2 Associations between baseline physical activity and risk of chronic LBP

Physical activity in leisure time (hours per week)			Women		Men
Physical activity in leisure time (hours per week)			Adjustment for age	Additional adjustment^a	Adjustment for age	Additional adjustment^a
		Total	9616	9199	8452	8130
Light	Hard	Score	RR (95 % CI)	RR (95 % CI)	RR (95 % CI)	RR (95 % CI)
<1	0	1	1.00 (reference)	1.00 (reference)	1.00 (reference)	1.00 (reference)
≥1	0	2	0.94 (0.83–1.05)	0.97 (0.86–1.09)	0.96 (0.82–1.13)	1.03 (0.87–1.21)
	<1^b	3	0.92 (0.81–1.05)	0.99 (0.87–1.13)	0.88 (0.75–1.03)	0.96 (0.82–1.14)
	1–2	4	0.81 (0.71–0.93)	0.89 (0.77–1.03)	0.71 (0.60–0.85)	0.81 (0.68–0.97)
	≥3	5	0.94 (0.77–1.14)	1.05 (0.86–1.27)	0.85 (0.70–1.03)	0.96 (0.79–1.17)
P, categorical effect			0.045	0.36	0.001	0.06
P, linear effect^c			0.016	0.46	0.001	0.07
P, quadratic effect^d			0.39	0.56	0.33	0.69

LBP chronic low back pain, RR relative risk, CI confidence interval
^aAdjustment for age, education, work status, physical activity at work, BMI, smoking
^bMust have reported some hard activity
^cFor linear effect of score for physical activity
^dFor quadratic effect of score for physical activity, in model also including linear effect

ISSN: 1471-2458