Groeneveld et al. BMC Public Health 2011, 11:836 http://www.biomedcentral.com/1471-2458/11/836 Page 5 of 9 Did not attend T1 n=84 (20.6%) Did not attend T2 n=91 (22.3%) Invited n=4,058 Participants n=816 Not willing to participate n=3,242 Reasons responders: No interest n=104 Medical treatment n=96 Feeling healthy n=88 No time/ money n=84 Other n= 90 Non-responders: n= 2,780 T0 intervention Total group n=408 EB: n=293 SC: n=115 T1 intervention Total group N=324 EB: n=236 SC: n=88 T2 intervention Total group N=317 EB: n=229 SC: n=88 T0 control Total group n=408 EB: n=280 SC: n=123 Don’t know: n=5 T1 control Total group N=347 EB: n=249 SC: n=98 T2 control Total group N=328 EB: n=237 SC: n=91 Did not attend T1 n=61 (15.0%) Did not attend T2 n=80 (19.6%) Intervention group Used for analyses: n=288 (70.6%) EB: n=208 SC: n=80 Control group Used for analyses: n=307 (75.2%) EB n=225 SC: n=82 Figure 1 Flow diagram of the progress through the phases of the study. using MI techniques for workers in the construction industry with an elevated risk of CVD. At 6 months, the intervention had a statistically significant beneficial effect on snack intake, fruit intake, and smoking. At 12 months, most of the initial improvements in the intervention group were still present, although the effects on smoking and fruit intake were no longer significant. At 12 months, i.e. 6 months after the intervention had ended, a significant effect was found on snack intake. Moreover, at 12 months, a statistically significant beneficial effect was found on alcohol consumption among the normal weight partici- pants. No statistically significant intervention effects were found for time spent on leisure time PA and sports, or on MET-minutes per week. Work type did not modify any intervention effect, implying that the intervention is equally effective in blue- and white-collar workers. Interpretation of findings Physical activity had substantially increased in both the intervention and the control group at 6 months (+172 vs.