A punching bag system is provided for determining the position of a
punching bag. A punching bag is suspended by a coupling from a stand
which permits the punching bag to travel between an up position where it
is in contact with a contact area on the stand, and a down position where
it is free from contact with the stand. Light-emitting devices and
light-receiving devices are radially positioned on the stand between the
coupling and the contact area. Light is emitted from the light-emitting
devices and reflected into the light-receiving devices when the punching
bag is in the up position. The light-receiving devices generate an output
proportional to the amount of light received therein which is analyzed to
determine if the punching bag is in the up position. A metric is
determined based in part on the determined position and is presented by
an output device.