B-fold is right, even a 12 year old girl should be strong enough to spot you, if you are using correct weights.  Usually you only need about 5-10 lbs of force to get the weight past your sticking point.  That is unless you're totally fried, hurt yourself, or have gone way past your limit.  However, I can understand wanting a big burly dude their just in case.  I was once spotting someone and the bar slipped out of their hands.  It took all my strength to get it off him.