Groeneveld et al. BMC Public Health 2011, 11:836 http://www.biomedcentral.com/1471-2458/11/836 Page 6 of 9 Table 1 Intervention effects in the energy balance subgroup, as determined by linear regression analysis, adjusted for body mass index n Baseline mean (SD) 6 months mean (SD) b 6 months (95%CI) 12 months mean (SD) b 12 months (95%CI) Leisure time physical activity (minutes per week) Intervention 207 429.7 (390.0) 589.7 (464.2) 59.5 (-11.3; 130.3) 543.4 (462.5) Control 222 466.0 (349.0) 552.8 (424.6) 529.4 (409.2) Sports activities (minutes per week) Intervention 207 95.1 (116.6) 107.3 (130.7) 10.1 (-9.6; 29.7) 109.9 (139.8) Control 223 77.9 (126.8) 84.7 (139.0) 96.5 (143.3) Leisure time physical activity- and sports-related energy expenditure (MET-minutes per week) Intervention 206 2,130.5 (1,494.9) 2,852.4 (1,769.7) 226.5 (-81.6;534.5) 2,678.6 (1,838.4) Control 223 2,209.5 (1,543.8) 2,672.5 (2,060.1) 2,591.1 (1,899.0) Alcohol (glasses per week) Intervention 196 9.6 (9.9) 8.8 (9.07) -1.3 (-2.7; 0.1) 8.8 (8.9) Control 213 9.6 (9.5) 10.2 (10.21) 9.9 (10.6) Snacks (pieces per week) Intervention 207 14.1 (11.21) 11.1 (11.1) -1.9 (-3.7; -0.02)* 12.1 (9.2) Control 220 13.1 (9.8) 12.6 (11.9) 13.6 (11.2) Fruit (pieces per week) Intervention 207 10.1 (6.9) 11.8 (8.1) 1.7 (0.6; 2.9)* 11.7 (8.3) Control 221 10.8 (8.6) 10.7 (7.9) 11.3 (7.8) Vegetables (spoons per week) Intervention 207 17.0 (9.5) 18.0 (9.2) 0.9 (-0.6; 2.4) 17.5 (8.8) Control 222 17.7 (10.3) 17.3 (8.3) 7.7 (8.8) 30.2 (-45.3; 105.8) 2.2 (-19.0; 23.5) 132.2 (-177.7; 442.0) -1.0 (-2.5; 0.4) -1.9 (-3.6; -0.2)* 0.9 (-0.2; 2.1) 0.04 (-1.4; 1.4) . * p < 0.05 SD: standard deviation; CI: confidence interval; MET: metabolic equivalent. + 94 minutes per week) and at 12 months (+129 vs. + 84 minutes per week), but the intervention effect was not significant. This is not in line with the reviews of Dugdill et al. (2008) and Conn et al. (2009), who concluded evi- dence for the effect of workplace counseling on PA [28,29]. The lack of a significant intervention effect in our study may be related to the high levels of baseline PA at work, or due to the relatively large amount of time spent on doing ‘odd jobs’ outside working hours. The age difference in the increase in PA may be explained by the fact that younger workers spent significantly more time in sports at baseline than the older ones (111 minutes vs. 69 minutes per week). Participating in sports might have lowered their urge to undertake physical activities of moderate intensity in leisure time. The lack of a statisti- cally significant effect on PA is unfortunate, since Ruzic et al. (2003) demonstrated that a high physical load at the Smoking (%) Intervention Control * p < 0.05 OR: odds ratio; CI: confidence interval. n 80 82 Baseline % 100 100 workplace (or while doing odd jobs) did not induce positive changes in aerobic capacity, strength, or flexibil- ity of male workers aged 20-60 [30]. Thus, in a future study, another strategy should be sought for stimulating engagement in leisure time PA among workers in the construction industry. With respect to diet, notable improvements were found in the intervention group. Pignone et al. (2003) also concluded that medium to high intensive interventions generally produced medium to large changes in dietary behavior, but they found no spe- cific differences in effectiveness on fat or fruit and vegeta- ble intake [31]. In our study, especially the consumption of snacks was affected, possibly because participants rea- lized that decreasing snack intake has a direct effect on losing body weight, which may have been their main goal. The effect on snack intake was modified by age, implying a more favorable effect among the younger Table 2 Intervention effects in the smoking cessation subgroup, as determined by logistic regression analysis. 6 months % 68.7 86.6 OR (95% CI) 0.3 (0.1; 0.7)* 12 months % 76.3 80.5 OR (95% CI) 0.8 (0.4; 1.6)