A bass note run is a series of single notes played on the bass strings. They are used to connect two chords, adding interest to a given progression.
In the following example each bass note run begins on the 4th beat of the bar (indicated by the brackets). The run is played by the thumb, giving the pattern:
Pattern 11
Pattern Eleven
Bass note runs introduce the technique of playing notes that are outside the chord, e.g., the F# note in the first bar is not a part of the G chord. This is in contrast to all previous exercises, which have involved only the playing of notes within a chord (i.e., holding a chord shape).
You should experiment with your own bass note run, using the previous progression and others that you have studied.