Although the PA-promoting message had no direct effect on MVPA , the results showed that ( a ) this message increased intentions to practice PA , notably among participants with low or moderate ( but not high ) baseline intentions ; ( b ) objective MVPA was positively predicted by postmessage PA intentions and IAPA , and negatively predicted by IASB ; and ( c ) postmessage PA intentions predicted MVPA for individuals with low or moderate ( but not high ) IASB .