If you are listening to a track with chapter marks and you want to go to the next track, you can press Next to advance to the next chapter. When you get to the last chapter and press Next, you will advance to the next track. The same applies for pressing Previous to go to the previous chapter or track.
Note that if you skip a track with chapter marks this way, iPod will reset the bookmark to the beginning of the track. In addition, if you are listening to a track with 20 or more chapter marks, pressing Previous or Next may not be the most convenient way for you to skip the track, especially while in a workout.
Tip: During a workout, a better way to skip a track with chapter marks and also preserve the bookmark position is to press Menu, and then select "Change Workout Music". Then select "Resume Workout" after you have selected a different track.