The folks at Advancer Technologies just release a muscle sensor board with a great walk through posted on Instructables describing how this board measures the flexing of muscles using ...

The conventional electromyography (EMG) approach uses metal electrodes ... that produce rhythmic activation of muscles. This enables smooth limb coordination and walking pattern transitions.

How much more difficult is it for our countrymen who have limb differences to move if it is already tough for us?) The EMG sensor picks up the muscle activity or muscle signal from the person ...