The effect of physical activity on spine health is poorly understood, particularly with respect to individual effects on bone, disc, and joint. We conducted a longitudinal study to determine the association between physical activity and incidence of VF, disc height narrowing (DHN), and facet joint osteoarthritis (OA) in women and men. Participants included 624 women and 512 men (mean age 62yr; range, 40-85yr) of the Framingham Study with baseline and 6-yr follow-up CT scans. VF, DHN, and OA from T4-L4 were scored as: 0=normal, 1=mild, 2=moderate, or 3=severe. Incidence was defined as any level scored ≤1 at baseline and >2 at follow-up. Physical activity was assessed using the Framingham Physical Activity Index (PAI). Robust Poisson regression was used to compute relative risk (RR) and associated 95% confidence intervals (CIs) quantifying the estimated association between PAI and incidence of VF, DHN, and OA, adjusted for age, height, weight, and smoking. Incidence of VF was 6% in women and men; DHN 40% women, 33% men; OA 35% women, 25% men. Mean PAI (range 26-78)±SD was 37±6 in women and 38±7 in men. In women, VF incidence appeared to increase with higher PAI (trend, p=0.08), but there was no association in men (TABLE). There was a suggestion of a trend in increasing incidence of DHN with increasing PAI in men (trend, p=0.05) but not women (trend, p=0.41). In contrast, incidence of OA declined with increasing PAI in men (trend, p=0.03) but there was no association in women (trend, p=0.63). We found that increased levels of physical activity did not significantly increase risk of VF, DHN, or OA, and may protect against OA in men. Differences in the specific type or intensity of activities between women and men may contribute to differences observed in the associations between PAI and spinal degeneration.
|PAI||Vertebral Fracture (VF)||Disc Height Narrowing (DHN)||Facet Joint Osteoarthritis (OA)|
|Q1 (low)||1.0 (ref)||1.0 (ref)||1.0 (ref)||1.0 (ref)||1.0 (ref)||1.0 (ref)|
|Q2||0.9 (0.3, 2.5)||1.1 (0.3, 3.4)||1.1 (0.7, 1.7)||1.1 (0.8, 1.5)||1.0 (0.7, 1.5)||1.0 (0.7, 1.3)|
|Q3||1.0 (0.4, 2.7)||1.7 (0.6, 4.5)||1.5 (1.0, 2.1)||1.1 (0.7, 1.4)||0.8 (0.5, 1.2)||1.1 (0.8, 1.5)|
|Q4||1.1 (0.4, 3.1)||2.0 (0.8, 5.3)||1.4 (0.9, 2.0)||1.1 (0.9, 1.5)||0.7 (0.4, 1.0)||1.0 (0.8, 1.4)|
Disclosure: The authors declared no competing interests. This work was supported by the National Institutes of Health, National Institute on Aging R01 (AG041658, 2011-2016).