For years it has been the practice of baseball batters to swing a weighted bat before taking their turn to hit. The thinking was that this type of warm-up activity would lighten the feel of the regular (i.e., unweighted) bat and improve the speed of the swing. Research examining the validity of this notion suggests that, although swinging a weighted bat may alter batters’ perceptions of bat heaviness and swing speed, it does not influence actual swing speed (Otsuji, Abe, & Kinoshita, 2002).
In this study, eight baseball and softball players attempted three sets of 15 bat swings during which they hit a ball suspended on a cord. Batters performed the first five swings and the last five swings in each set with a regular (nonweighted) bat and the middle five swings with a weighted bat. They were asked to estimate swing speed and bat weight (compared with the speed and weight they perceived during the first five unweighted swings) following the fifth weighted swing and after the first, third, and fifth unweighted swings. Actual swing speeds did not increase following swings with the weighted bat, but batters perceived their swings to be faster and their bats to feel lighter. For five of the eight participants, this illusion lasted for at least four unweighted swings. In another study (Southard & Groomer, 2003), the normal swing pattern of experienced batters was found to be altered and their swing speed slowed down for up to five swings following a warm-up with a weighted bat. The results of these studies suggest that batters would be better off taking warm-up swings with their normal (unweighted) bat than with one that is considerably heavier.
This is an excerpt from Motor Learning and Performance: A Situation-Based Learning Approach, Fourth Edition.