A baseball doughnut is a weighted ring that fits over the end of a baseball bat

Baseball bat

A baseball bat is a smooth wooden or metal club used in the game of baseball to hit the ball after the ball is thrown by the pitcher. It is no more than 2.75 inches in diameter at the thickest part and no more than 42 inches in length. It typically weighs no more than 33 ounces , but it...

, used for warming up during a baseball

Baseball

Baseball is a bat-and-ball sport played between two teams of nine players each. The aim is to score runs by hitting a thrown ball with a bat and touching a series of four bases arranged at the corners of a ninety-foot diamond...

 game. When the doughnut is taken off, the bat becomes lighter, allowing the batter to feel like it is easier to swing harder. This process is known as deceleration training. The donut was invented by catcher

Catcher

Catcher is a position for a baseball or softball player. When a batter takes his turn to hit, the catcher crouches behind home plate, in front of the umpire, and receives the ball from the pitcher. This is a catcher's primary duty, but he is also called upon to master many other skills in order to...

 Elston Howard

Elston Howard

Elston Gene Howard was an American Negro League and Major League Baseball catcher, left fielder and coach. During a 14-year baseball career, he played from 1955–1968, primarily for the New York Yankees...

, in the early 1960s, and was originally called "Elston Howard's On-Deck

On-deck

In baseball, on deck refers to being next in line to bat. In a professional game, the batter who is on deck traditionally waits in a location in the foul territory called the on deck circle....

bat weight". The weight was later dubbed the "doughnut" and the "iron doughnut".

In 2011 The Wall Street Journal reported a study from the University of Hawaii that showed using a baseball doughnut actually decreased a batter's speed at the plate after warming up with a baseball doughnut.