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 3 Risk of chronic LBP by combinations of age (in 20 year groups) and physical activity^a

Physical activity in leisure time (hours per week)			Women		Men
Physical activity in leisure time (hours per week)			30–49 years	50–69 years	30–49 years	50–69 years
		Total	5723	3476	4759	3371
Light	Hard	Score	RR (95 % CI)	RR (95 % CI)	RR (95 % CI)	RR (95 % CI)
<1	0	1	1.00 (reference)	1.16 (0.95–1.43)	1.00 (reference)	0.79 (0.61–1.03)
≥1	0	2	1.07 (0.91–1.26)	0.99 (0.83–1.18)	0.95 (0.77–1.18)	0.88 (0.71–1.11)
	<1^b	3	1.05 (0.89–1.25)	1.08 (0.88–1.34)	0.96 (0.78–1.17)	0.77 (0.60–0.99)
	1–2	4	1.03 (0.86–1.23)	0.73 (0.55–0.95)	0.80 (0.64–1.00)	0.65 (0.50–0.85)
	≥3	5	1.18 (0.93–1.50)	0.99 (0.70–1.41)	1.03 (0.81–1.30)	0.66 (0.48–0.90)
P, categorical effect ^c			0.69	0.006	0.22	0.11
P, linear effect^d			0.33	0.007	0.55	0.030
P, quadratic effect^e			0.92	0.69	0.22	0.36

LBP low back pain, RR relative risk, CI confidence interval
^aAdjustment for education, work status, physical activity at work, BMI, smoking
^bMust have reported some hard activity
^cFor categorical effect of physical activity, within 20 year age interval
^dFor linear effect of score for physical activity, within 20 year age interval
^eFor quadratic effect of score for physical activity, within 20 year age interval

ISSN: 1471-2458