Physical activity and body composition in patients with ankylosing spondylitis
Version of Record online: 28 DEC 2011
Copyright © 2012 by the American College of Rheumatology
Arthritis Care & Research
Volume 64, Issue 1, pages 101–107, January 2012
How to Cite
Plasqui, G., Boonen, A., Geusens, P., Kroot, E. J., Starmans, M. and van der Linden, S. (2012), Physical activity and body composition in patients with ankylosing spondylitis. Arthritis Care Res, 64: 101–107. doi: 10.1002/acr.20566
- Issue online: 28 DEC 2011
- Version of Record online: 28 DEC 2011
- Accepted manuscript online: 31 AUG 2011 06:10AM EST
- Manuscript Accepted: 26 JUL 2011
- Manuscript Received: 30 MAR 2011
Patients with ankylosing spondylitis (AS) are at risk for accelerated muscle loss and reduced physical activity. Accurate data are needed on body composition and physical activity in this patient group. The purpose of this study was to investigate body composition and objectively assessed physical activity in patients with AS.
Twenty-five AS patients (15 men, mean ± SD age 48 ± 11 years) were compared with 25 healthy adults matched for age, sex, and body mass index. Body composition was measured using a 3-compartment model based on air-displacement plethysmography to assess body volume and deuterium dilution to assess total body water. The fat-free mass index (FFMI; fat-free mass divided by height squared) and the percent fat mass (%FM) were calculated. Daily physical activity was assessed for 7 days using a triaxial accelerometer and physical fitness with an incremental test until exertion on a bicycle ergometer. Blood samples were taken to determine C-reactive protein (CRP) level and tumor necrosis factor α.
Accelerometer output (kilocounts/day) showed the same physical activity level for patients and controls (mean ± SD 319 ± 105 versus 326 ± 66). There was no difference in the FFMI or %FM between the patients and controls. Physical activity was positively related to the FFMI (partial R = 0.38, P = 0.01) and inversely related to CRP level (R = −0.39, P < 0.01), independent of group. CRP level was inversely related to the FFMI, but the effect was less strong than with physical activity (partial R = −0.31, P = 0.03).
Daily physical activity may help preserve fat-free mass in patients with AS.