When it comes to weight lifting, not paying attention to how you're holding the bar can not only be dangerous, it may even be holding back your overall results. That's because maintaining the same exact grip on the bar every single time you lift works your muscles the same exact way, over and over again. "Varying where and how you hold the bar can rechannel your efforts to different fibers within the same muscle group," says Wayne Westcott, Ph.D., fitness research director at the South Shore YMCA in Quincy, Massachusetts. "The end result can leave you with a more thoroughly-worked…