ORIGINAL ARTICLE Heavy domestic, but not recreational, physical activity is associated with low back pain: Australian Twin low BACK pain (AUTBACK) study Markus Hu ¨bscher • Manuela L. Ferreira • Daniela R. G. Junqueira • Kathryn M. Refshauge • Chris G. Maher • John L. Hopper • Paulo H. Ferreira Received: 11 July 2013 / Revised: 19 February 2014 / Accepted: 20 February 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Purpose To evaluate the association between domestic and recreational physical activity (PA) and low back pain (LBP) after adjusting for genetic and environmental influences. Methods Twins were recruited through the Australian twin registry. LBP prevalence and domestic (vigorous gardening/heavy yard work) and recreational (light walk- ing, moderate/vigorous) PA were assessed by a validated questionnaire. Associations were analysed using a cross- sectional analysis of the complete sample of 486 twins, including a matched case–control analysis of 69 twin pairs discordant for LBP. Logistic regression and the lincom post-estimation method were used for the analysis. Odds ratios (OR) with 95 % confidence intervals (CIs) were calculated. Results The case–control analysis showed that LBP was significantly associated with heavy domestic PA (OR 2.88, 95 % CI 1.29–6.43), whereas no significant association was found with any form of recreational PA. The results of the lincom command indicated that being engaged in both heavy domestic and recreational PA (light walking or moderate/vigorous) was associated with a significantly increased probability of LBP compared with being engaged only in recreational PA (light walking or moderate/vigor- ous, ORs 3.48–4.22). Using the whole sample, we found weaker associations but in the same direction. Conclusions We found evidence that heavy domestic PA is associated with an increased probability of LBP, and the combination of heavy domestic and recreational PA might increase the probability of LBP more so than heavy domestic or recreational PA alone. Associations being greater when using the co-twin case–control analysis indicate that genetic and environmental factors influence the relationship between PA and LBP, and demonstrate the value of a twin design. Keywords Twin study Á Low back pain Á Physical activity Á Physical workload Introduction Contemporary guidelines for the prevention and manage- ment of low back pain (LBP) emphasize the importance of regular physical activity (PA) and exercise [1, 2]. Sur- prisingly, the question of whether physical inactivity in M. Hu ¨bscher Á D. R. G. Junqueira Á K. M. Refshauge Á P. H. Ferreira Faculty of Health Sciences, The University of Sydney, Sydney, Australia M. Hu ¨bscher Neuroscience Research Australia and The University of New South Wales, Sydney, Australia M. Hu ¨bscher (&) 75 East St, Lidcombe, NSW 2141, Australia e-mail: m.huebscher@neura.edu.au M. L. Ferreira Á C. G. Maher The George Institute for Global Health, Sydney Medical School, The University of Sydney, Sydney, Australia D. R. G. Junqueira Centro de Estudos Do Medicamento (Cemed), Departamento de Farma ´cia Social, Faculdade de Farma ´cia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil J. L. Hopper Centre for Molecular, Environmental, Genetic, and Analytic Epidemiology, The University of Melbourne, Melbourne, Australia 123 Eur Spine J DOI 10.1007/s00586-014-3258-2