Okay, I have to admit it. I have absolutely no idea what a Metragenix bar is, but it sure sounds high-tech–like maybe if I eat one, I’ll be able to instantly run a marathon or something! I guess we’ll all be able to find out, because we can score a free bar at participating GNC locations! Click here to print the coupon which is valid through 8/24. There is a limit of one coupon per person.