What is the sign language sign for strength?

This is the ASL (or American Sign Language) sign for Strength. Other Sign Languages may have different signs.

Make a hand shape like you would do if you were going to slap someone five with both hands. Take the tips of your fingers and put them near your armpits (left hand near left armpit, right hand near right armpit) then pull the hands forward and close into fists (like you're pulling the strength from your body).