Lail et al. BMC Public Health 2011, 11:148 http://www.biomedcentral.com/1471-2458/11/148 Neighbourhood walking for recreation Neighbourhood walking for transportation Dog ownership status Non-owners Owners Non-owners Table 2 Comparison of usual weekly minutes walking for recreation and transportation inside the neighbourhood in summer and winter among dog-owners and non-owners Summer Winter Mean(SD) 95%CI Mean(SD) 95%CI Mean difference 95%CI 123.3 (157.7) 105.8,140.9* 107.1 (135.9) 92.0, 122.2* 213.6 (206.8) 74.9 (123.7) 175.4, 251.8* 61.2, 88.7 253.2 (211.8) 69.8 (119.3) 214.0, 292.3* 56.5, 83.1 Mean difference in minutes between winter and summer within dog-ownership status 16.2 -39.6† 5.2 -0.83 Page 5 of 7 -2.3, 34.8 -70.2, -8.9 -7.4, 17.8 -21.6, 19.9 Owners 59.1 (128.2) 35.4, 82.8 59.9 (112.6) 39.1, 80.7 *Significant difference between dog-owners and non-owners within season (p < .05). † Change in minutes from winter to summer significantly different between dog-owners and non-owners (p < .05). Negative values: mean walking minutes in winter > mean minutes of walking in summer. Positive values: mean minutes of walking in summer > mean minutes of walking in winter. All results adjusted for age, sex, ethnicity, marital status, income, education and type of house. dog-owners were no more or less likely than non-owners to participate in NTW, in summer, in winter, or in both seasons (Tables 1 and 3). Discussion Of the dog-owners in our sample, 63% reported walking their dog in both summer and winter; similarly, Austra- lian research found that the majority of dog owners reg- ularly walked their dogs [28]. Overall, dog-owners reported greater participation in NRW than did non- owners, supporting previous studies showing dog-own- ers to be more physically active than non-owners in recreational walking [11,19,29,30]. Yet our finding that dog-owner’s participation in physical activity remained relatively stable from winter to summer is novel, as is the finding that dog-owners’ NRW increased in winter, while non-owners’ NRW decreased. Overall, our study’s longitudinal design allowed us to pose questions and draw conclusions that are not possi- ble with cross-sectional data. To the best of our knowl- edge, research investigating dog-ownership as a factor in longitudinal patterns in neighbourhood walking has not previously been undertaken. Compared to non-owners, dog-owners walked more for recreation in both the win- ter and summer, which corresponds with previous studies that found dog-owners spend more time in mild to mod- erate physical activity, including walking [11,19,31] and in recreational physical activity [30]. Moreover, dog-owners’ NWR, on average, was equivalent of 30-minutes/day regardless of season - the recommended minimum amount of physical activity to accrue health benefits [32]. In contrast, non-owners, on average, were not achieving this level of NWR, and in fact reported slightly less NWR in winter than in summer. Table 3 Odds ratios (OR) and 95% confidence intervals (95%CI) showing the association between walking for recreation and transportation inside the neighbourhood during a usual week (i.e., none vs. any) from winter to summer and dog ownership status Dog ownership status Non-owners Owners Neighbourhood walking for recreation Neighbourhood walking for transportation Consistent Summer Winter participator1 participator2† participator3 Consistent non- participator4 Consistent participator1 Summer Winter participator2 participator3 Consistent non- participator4 OR (95%CI) 1.00 3.28 (1.86, 5.79)* OR (95%CI) OR (95%CI) - - 1.00 1.05 (0.49, 2.23) OR (95%CI) 1.00 0.35 (0.16, 0.79)* OR (95%CI) OR (95% CI) OR (95%CI) 1.00 0.65 (0.40, 1.05) 1.00 0.91 (0.45, 1.83) 1.00 1.44 (0.75, 2.74) OR (95%CI) 1.00 1.41 (0.86, 2.30) * Participation significantly different between dog-owners and non-owners (p < .05) †All respondents who participated in NWR during summer but not winter were non-owners. 1Walked in both summer and winter. 2Walked in summer only. 3Walked in winter only. 4No walking in summer and winter. All results adjusted for age, sex, ethnicity, marital status, income, education and type of house.