An elderly woman goes for a leisurely walk. Two young men in excellent physical condition are directly behind her, sprinting toward her. No matter how fast they run, they do not catch up with the woman.

Clues:
The men are running as fast as they can.
There are other people in the same area.
The men always stay seven feet behind the woman.
All three people paid money to be where they are.
The men are not moving forward.
All three people are indoors.

They're all at the gym/ health club
On treadmills