Is there a U-shaped relationship between physical activity in leisure time and risk of chronic low back pain? A follow-up in the HUNT Study.

Ingrid Heuch,Ivar Heuch,Knut Hagen,John-Anker Zwart

doi:10.1186/s12889-016-2970-8

Abstract

BackgroundPhysical activity in leisure time is often considered to have favourable effects on the risk of low back pain (LBP), but demonstrating a definite association in epidemiological studies has proven difficult. The purpose of the present study was to explore associations between physical activity and risk of chronic LBP in an adult population and to investigate whether relationships are limited to certain age groups or to females or males. A particular objective was to determine whether support could be found for a U-shaped relationship, with both low and high activity levels carrying greater risk.MethodsThe relationship between physical activity and risk of chronic LBP was examined in a Norwegian prospective study using data from the community-based HUNT2 and HUNT3 surveys. Participants were 9616 women and 8452 men without LBP at baseline, who reported after 11 years whether they suffered from LBP. Associations between baseline physical activity in leisure time and risk of chronic LBP at end of follow-up were evaluated by generalized linear modelling with adjustment for potential confounders.ResultsSignificant associations between leisure time physical activity and risk were observed in both sexes after age adjustment, mainly suggesting inverse relationships. Women participating in hard physical activity 1–2 h per week had a relative risk (RR) of chronic LBP of 0.81 (95 % CI 0.71–0.93) compared to those with only light physical activity less than 1 h per week. The corresponding RR in men was 0.71 (95 % CI 0.60–0.85). After adjustment for education, employment, occupational activity, body mass index (BMI) and smoking, significant relationships could only be demonstrated in those aged 50 years or more at baseline. The associations differed between female educational groups, with more U-shaped relationships being observed among women with basic education only.ConclusionNo strong support was found overall for U-shaped relationships. However, no further general decrease in risk was seen among those with 3 h or more of hard physical activity per week. The contrasts observed between female educational groups may reflect different preferences regarding specific strenuous activities. Men aged 50 years or more seem in particular to benefit from hard physical activities.

Highlights

Physical activity in leisure time is often considered to have favourable effects on the risk of low back pain (LBP), but demonstrating a definite association in epidemiological studies has proven difficult
The follow-up in this study aimed at the cohort consisting of 31,145 individuals without chronic LBP aged 30–69 years when they participated in the HUNT2 survey, with information available on physical activity in leisure time
All statistical analyses were carried out using IBM SPSS version 21 (IBM Corp., Armonk, New York). In both sexes the percentage of chronic LBP at end of follow-up diminished with increasing levels of baseline physical activity in leisure time, except in the category with hard physical activity of duration ≥3 h per week (Table 1)

Summary

Introduction

Physical activity in leisure time is often considered to have favourable effects on the risk of low back pain (LBP), but demonstrating a definite association in epidemiological studies has proven difficult. Physical activity does not generally seem to predict future disability or pain levels in LBP patients [6], such activity may improve prognosis in particular patient categories [7]. Occupational physical activities have been considered in many studies, and particular types of workrelated stress seem to confer a higher risk of LBP [8, 10], the overall evidence in support of a causal relationship is not very strong [11]. The direction of the potential relationships with risk of LBP may differ between activities at work and in leisure time, with heavy work loads conferring a higher risk, whereas extensive leisure time physical activity may be more favourable [12]

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