Ok guys, I’ve been researching and debate over this topic for about a week now. My orginial idea was that seeing how baseball players swing with a heavier bat prior to stepping in the batters box why not swing with a ligther bat? With the heavier your teaching yourself to swing a heavy load and with the ligther bat your teaching yourself to swing with more velocity.Very much like Post tetnaic Faciliation brought up by Poliquin
I found 2 stuides
The purpose of this study was to determine if warm-up with baseball bats of different moments of inertia has an effect on swing pattern and bat velocity. Ten experienced baseball players (ages 20-25 years) voluntarily participated in this study. Each participant was required to complete 10 dry swings (5 warm-up and 5 postwarm-up) at maximum effort within 3 different conditions. Post warm-up was always with a standard bat (I = .27 kgm2; 83.8 cm, 9.1 N). Warm-up for Condition 1 was with the standard bat. Condition 2 required participants to warm up with a standard bat plus a 6.1 N lead donut (I = .49 kgm2, 83.8 cm, 15.6 N). Condition 3 required participants to warm up with a hollow plastic bat (I = .08 kgm2; 83.8 cm, 3.34 N). Quantitative and qualitative analyses indicated that following warm-up with the weighted bat (largest moment of inertia), swing pattern was significantly altered, and post warm-up velocity was the lowest of the three conditions."
In baseball and softball, warm-up swings with a weighted bat have been believed to increase swing velocity when an ordinary bat is used in the subsequent competitive situation. The purpose of this study was to investigate the after-effects of using a weighted bat on subsequent swing velocity and batters’ perceptions of swing velocity and heaviness. Eight men in varsity softball and baseball hit a ball suspended from the ceiling 45 times (3 sets of 15 trials). For each set, the initial 5 trials were done using an ordinary 920-g wooden bat (Control condition), and the following 5 trials by a bat with an 800-g bat ring (Weighted condition), and the final 5 trials again by the ordinary bat (post-Weighted condition). Analysis of variance showed a significant decrease of 3.3% in the measured linear velocity of the bat prior to impact with the ball for the first swing of the post-Weighted condition compared with the Control condition. From the second swing the velocity returned to the level of the Control condition. Subjective judgment of the heaviness and velocity of swings for the Weighted and post-Weighted conditions by each participant showed that the ordinary bat felt lighter and swing speed felt faster for the post-Weighted condition. The advantage of the warm-up with a weighted bat was thus psychological and not biomechanical.