Feats of amazing Human strength are well documented and are probably related to the Fight or Flight defence mechanism, this allows a person with limited ability, perform act in the course of an emergency situation to save either themselves or a loved one.
One random example ...
HowStuffWorks "How can adrenaline help you lift a 3,500-pound car?"
Self belief can also provide this type of action - the activities of eastern mystics in lying on beds of nails or walking over hot coals.
If this band instils this belief then fair enough but don't listen to the hocus pocus from the salesman as fact