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Kjaer P.1,2, Andersen J.T.3, Boyle E.1
1University of Southern Denmark, Department of Sports Science and Clinical Biomechanics, Odense, Denmark, 2Spinecenter of Southern Denmark, Department of Regional Health Services, Middelfart, Denmark, 3Metropolitan University College, Copenhagen, Denmark
Background: Whereas exercise is generally regarded helpful in low back pain (LBP) conditions, the relevance of the level of physical activity is less understood. Potentially, certain levels of physical activity may either have a preventive effect or increase the risk of LBP. This contradiction has been explained in three different ways:
1) deconditioning paradigm;
2) an U-shaped relationship; and
3) fear avoidance theory.
They all add to the complexity in understanding the link between LBP and physical activity. Therefore, it remains unclear whether low or high levels of physical activity lead to LBP or vice versa.
1) deconditioning paradigm;
2) an U-shaped relationship; and
3) fear avoidance theory.
They all add to the complexity in understanding the link between LBP and physical activity. Therefore, it remains unclear whether low or high levels of physical activity lead to LBP or vice versa.
Purpose: The purpose of this study was to reach a better understanding of levels of physical activity in relation to LBP. We described the cross-sectional associations between physical activity and LBP at ages 41, 45 and 49 years. We determined if there were longitudinal associations between physical activity and LBP four and eight years later. Finally, we determined if the changes in the reporting of physical activity was influenced by previous LBP.
Methods: The study population was the `Backs on Funen Cohort´, a sample representative of the Danish general population. Participants were interviewed on three occasions. The outcome non-trivial LBP was defined as having LBP for more than 30 days in the previous year that resulted in at least one consequence (e.g., sought care for LBP, modified work, reduced working hours, or reduced leisure time activity). Physical activity was defined by the total number of hours per week engaged in various sporting activities and categorised into five subgroups. Associations were studied using generalised linear models adjusted for sex and BMI.
Results: Four hundred and twelve, 348 and 293 participants completed the three surveys. The prevalence of non-trivial LBP ranged from 18% to 20% and the mean number of hours spent in sports was 4.2, 5.4 and 2.1 at the three time-points. There were no statistical significant cross-sectional or longitudinal associations between time spent in sports and LBP. Over time, 55% lowered their participation in sports. Participants with LBP did not report fewer hours in sports than those without LBP previously; however, participants reporting previous LBP were more likely to report it in the future (9-17% versus 25-100%).
Conclusion(s): None of the proposed relationships between LBP and levels of physical activity were confirmed. High or low number of hours spent in sports did not increase the risk of LBP with consequences. Most of the participants reduced their hours spent in sports with age, but people with LBP did not reduce the time spent in sports more than people without LBP. Previous reporting of LBP most strongly predicted future LPB.
Implications: The results are provocative because they challenge general beliefs about the positive aspects of physical activity in relation to LBP, but maybe it is time to challenge these general beliefs.
Funding acknowledgements: The study was supported by a grant from Industrial Insurance Company, now topdanmark.
Topic: Musculoskeletal: spine
Ethics approval: The study was approved by The Regional Committees on Health Research Ethics for Southern Denmark (ref. no. 20000042)
All authors, affiliations and abstracts have been published as submitted.
