I thought I would pass on this incident told to me by an American friend who works for the FAA.
He was at an air show and allowed to sit on the flight deck of one those giant Russian Anatov transporters during take off. The plane taxied to the end of the runway and then sat there for 5 minutes with brakes on but with engines reving at full power. After take off he asked the pilot why they did this. The pilot replied "Pre-flight safety check. The manual says if the engines don't blow up after 5 mins at full power, then it's safe to take off."