Prepare your session for loops.

To begin, switch to Multitrack View in Adobe Audition, and select the track you want the loop in. Next, choose View > Display Time Format > Bars And Beats to set the time ruler to show measures and beats in your tracks. Then, choose Edit > Snapping > Snap To Ruler (Coarse) so that when you move or extend loops, they automatically snap to the bars and beats.

With these two commands, you can easily line up loops to the rhythm of your tracks.