Are runners or pedestrians allowed to use the bike lane?
Most US State and Local laws are based on the Uniform Vehicle Code and American Association of State Highway and Transportation Officials (AASHTO) guidelines. They will normally have a phrase like:


  Where sidewalks are provided, it shall be unlawful for any pedestrian to walk along and upon an adjacent roadway.


And a phrase like:


  Where sidewalks are not provided, any pedestrian walking along and upon a highway shall, when practicable, walk only on the shoulder on the left side of the roadway.


So, the short answer is "no", but may be different wherever you are.

The longer answer is that just like cyclist are allowed to take the lane when conditions warrant, pedestrians are allowed there when conditions warrant.

Ultimately we are all trying to share a limited amount of space. Courtesy from all parties is always appreciated, and usually returned.