title: The relationship between low back pain and leisure time physical activity in a working population of cleaners--a study with weekly follow-ups for 1 year.
abstract: BACKGROUND
  Low back pain (LBP) and leisure time physical activity (LTPA) are considered to be closely related, and clinical guidelines for the treatment of acute LBP recommend patients stay physically active. However, the documentation for this recommendation is sparse and based on studies involving patient populations. The purpose of the study was (1) to investigate the correlation between LBP and LTPA on a weekly basis over the course of a year in a high-risk group of cleaners; and (2) to investigate if maintaining LTPA during an episode of acute LBP has a positive effect on LBP intensity in the subsequent 4 weeks.
  
  
  METHODS
  188 cleaners consented to participate in a 52-week text message survey about hours of LTPA and intensity of LBP (from 0 to 9) over the previous 7 days. The correlation between LBP and LTPA was calculated by Pearson correlation coefficient. During an episode of acute LBP, a mixed effect logistic regression model was used to investigate whether cleaners who maintain LTPA have a lower pain intensity and higher probability of returning to initial pain intensity within the following four weeks compared with cleaners who decrease LTPA during acute LBP.
  
  
  RESULTS
  The correlation between weekly LTPA and LBP data was negative, but numerically low (r = -0.069) and statistically insignificant (p = 0.08). Among the 82 cleaners experiencing at least one episode of acute LBP, those maintaining LTPA during an episode of acute LBP did not have a lower pain intensity (average LBP intensity difference between groups of 0.06; 95% confidence interval (95% CI) of -0.417 to 0.539) or higher probability of returning to initial pain level (Odds ratio 1,02; 95% CI of 0.50 to 2.09) in the following four weeks compared with cleaners decreasing LTPA during acute LBP.
  
  
  CONCLUSIONS
  Hours of LTPA and intensity of LBP measured on a weekly basis throughout a year showed no close correlation. Maintaining LTPA during an episode of acute LBP did not result in a positive effect on LBP in the following 4 weeks. Documentation of LTPA recommendations for acute LBP in working populations is still needed.
authors.affiliation: National Research Centre for the Working Environment, Lersø Parkalle 105, DK 2100 Copenhagen Ø, Denmark.
authors.forename: Tobias
authors.initials: T
authors.lastname: Jespersen
authors.forename: Marie B
authors.initials: MB
authors.lastname: Jørgensen
authors.forename: Jørgen V
authors.initials: JV
authors.lastname: Hansen
authors.forename: Andreas
authors.initials: A
authors.lastname: Holtermann
authors.forename: Karen
authors.initials: K
authors.lastname: Søgaard
mesh_terms: D000328:Adult; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007899:Leisure Activities; D017116:Low Back Pain / Q000453:epidemiology / Q000503:physiopathology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009784:Occupational Diseases / Q000453:epidemiology / Q000503:physiopathology* / Q000517:prevention & control; D010809:Physical Fitness / Q000502:physiology*; D013995:Time