SHOULD I WARM-UP WITH A HEAVY BAT WHEN ON-DECK?

There are several studies that have been done regarding the effect of using a heavy bat or a bat weight (donut) when taking practice swings in the on-deck circle. The studies overwhelmingly show that swinging a bat that is more than 10%-15% heavier than your game-weight bat will actually reduce your bat speed. You can read one such study here. The section dealing with bat speed is the 4th page of the article (article page 1341) with a good summary on the next page of the article.