This article is from the Fitness FAQ, by Jeff Gleixner (glex@cray.com) with numerous contributions by others.
Lifting straps are worn around the wrist and wrapped tightly around
the bar. They are usually made out of a heavy cloth and have an
open loop at one end, so a loop may be made and your hand placed
through it. This allow you to lift more weight than your grip
can handle. Usually done while working the back, such as deadlifts,
various rows, pull-[ups/downs], and sometimes curls. Treat these
similar to lifting belts. Use them as a lifting aid for your heavy
sets. Do plenty of lighter sets to help improve your grip and forearm
strength.
 
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