Aluminum bats were introduced in the early 1970's and have since dominated the youth and amateur adult baseball and softball markets. Some studies have shown that aluminum bats may perform better than wood bats in two ways: (1) the balls "rebound" or come off metal bats faster and (2) the "batted speed" or the speed of the ball itself after it comes off the bat is faster. See Physics and Acoustics of Baseball & Softball Bats.

Most recently, some school systems and baseball leagues have banned aluminum bats due to a concern that their increased performance may endanger the safety of the youth baseball player.

Aluminum bats may outperform wood bats because (1) they may be swung faster, (2) they have a "trampoline effect" as the hollow bat acts like a spring, and (3) the batted ball speed away from the sweet spot is higher than in wood bats.

This increased performance has shown in some studies that aluminum bats may allow balls to be hit as much as 8-mph faster than a wood bat. These same studies have also indicated that the batted ball speed is often 20-30 mph faster than the pitched ball speed. Therefore, a pitch of 60 mph that is hit may have a batted ball speed of 80-90 mph when it goes into the field of play towards the youth baseball player. Until now, batters were protected from the 60 mph pitch with rigid helmets and nothing was done to protect pitchers and fielders from the 80 mph batted ball coming back at them.

So, youth baseball players that are fielding hits from aluminum bats will according to some studies have to react to batted balls that "rebound" faster, come at them with greater speed and go farther. Unfortunately, it is youth baseball players, ages 7-12, that may have slower reflexes or reaction times to deal with the increased speeds of aluminum bats compared to their older counterparts.