title: Physical inactivity is associated with narrower lumbar intervertebral discs, high fat content of paraspinal muscles and low back pain and disability.
abstract: BACKGROUND
  Although physical inactivity has been associated with numerous chronic musculoskeletal complaints, few studies have examined its associations with spinal structures. Moreover, previously reported associations between physical activity and low back pain are conflicting. This study examined the associations between physical inactivity and intervertebral disc height, paraspinal fat content and low back pain and disability.
  
  
  METHODS
  Seventy-two community-based volunteers not selected for low back pain underwent magnetic resonance imaging (MRI) of their lumbosacral spine (L1 to S1) between 2011 and 2012. Physical activity was assessed between 2005 and 2008 by questionnaire, while low back pain and disability were assessed by the Chronic Pain Grade Scale at the time of MRI. Intervertebral disc height and cross-sectional area and fat content of multifidus and erector spinae were assessed from MRI.
  
  
  RESULTS
  Lower physical activity levels were associated with a more narrow average intervertebral disc height (β -0.63 mm, 95% confidence interval (CI) -1.17 mm to -0.08 mm, P = 0.026) after adjusting for age, gender and body mass index (BMI). There were no significant associations between physical activity levels and the cross-sectional area of multifidus or erector spinae. Lower levels of physical activity were associated with an increased risk of high fat content in multifidus (odds ratio (OR) 2.7, 95% CI 1.1 to 6.7, P = 0.04) and high-intensity pain/disability (OR = 5.0, 95% CI 1.5 to 16.4, P = 0.008) after adjustment for age, gender and BMI.
  
  
  CONCLUSIONS
  Physical inactivity is associated with narrower intervertebral discs, high fat content of the multifidus and high-intensity low back pain and disability in a dose-dependent manner among community-based adults. Longitudinal studies will help to determine the cause and effect nature of these associations.
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, 99 Commercial Road, Melbourne, VIC, 3004, Australia. andrew.teichtahl@monash.edu.|Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, VIC, 3004, Australia. andrew.teichtahl@monash.edu.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Teichtahl
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, 99 Commercial Road, Melbourne, VIC, 3004, Australia. donna.urquhart@monash.edu.
authors.forename: Donna M
authors.initials: DM
authors.lastname: Urquhart
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, 99 Commercial Road, Melbourne, VIC, 3004, Australia. yuanyuan.wang@monash.edu.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, 99 Commercial Road, Melbourne, VIC, 3004, Australia. anita.wluka@monash.edu.
authors.forename: Anita E
authors.initials: AE
authors.lastname: Wluka
authors.affiliation: MRI Department, Healthcare Imaging Services, Epworth Hospital, 89 Bridge Road, Richmond, VIC, 3121, Australia. richard.o'sullivan@healthcareimaging.com.au.|Department of Medicine, Central Clinical School, Monash University, 89 Commercial Road, Melbourne, VIC, 3004, Australia. richard.o'sullivan@healthcareimaging.com.au.
authors.forename: Richard
authors.initials: R
authors.lastname: O'Sullivan
authors.affiliation: Menzies Research Institute, 17 Liverpool Street, Hobart, TAS, 7000, Australia. graeme.jones@utas.edu.au.
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, 99 Commercial Road, Melbourne, VIC, 3004, Australia. flavia.cicuttini@monash.edu.
authors.forename: Flavia M
authors.initials: FM
authors.lastname: Cicuttini
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D059350:Chronic Pain; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D064368:Healthy Volunteers; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology*; D016014:Linear Models; D017116:Low Back Pain / Q000175:diagnosis* / Q000209:etiology; D008159:Lumbar Vertebrae / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D064170:Paraspinal Muscles / Q000473:pathology*; D018570:Risk Assessment; D057185:Sedentary Behavior; D012737:Sex Factors; D011795:Surveys and Questionnaires