What bat should you use in the on-deck circle while getting loose?  Light bat, heavy bat, regular bat?  Is a donut really that bad?

This isn’t a new topic, but an article in Scientific America brings up the issue again with a new study in the Journal of Strength and Conditioning Research:

Warming up with 5 swings of a light or normal bat appears to increase post warm-up velocity of the normal bat when compared with warming up with a heavy bat after a rest period of 30 seconds. Within the bat weight spectrum of this study, it is suggested that when preparing to hit, 5 warm-up swings with either a light or normal bat will allow a player to achieve the greatest velocity of their normal bat.

Coop DeRenne, Montoya, Southard and Groomer are all other researchers that have found similar results – basically that bat speed will not be significantly slowed if the warm-up bat used immediately prior does not vary greatly (ie. +/- 13%) in weight from the regular bat.

The show Sports Science also did a piece on this where they showed a slight decrease in bat speed and altered timing after using a couple of donuts as added weight for warm-up swings:

So why do players still use weighted bats to warm-up?

Here are a couple of observations:

1. These images come from the Sports Science video comparing the swings pre- and post-weighted bat warmup.  The video mentions altered timing, but it’s interesting to me that the swing on the right after the weighted warmup is a shorter, quicker swing (this is assuming, of course, that the videos are synched up correctly to initiation of the swing).  All things being equal, I’ll trade 0.7 mph bat speed for the difference in the quickness of those swings.

2. I rarely see someone in the on-deck circle taking full effort hacks with a heavy bat, but players still want to feel good before they get into the box, and part of that for some is still using weighted implements to get loose.  As the player says in the video, it ‘feels’ better.  Understandably lame and non-scientific, but sometimes that’s the way it is…..especially in baseball where the mental game is significant.  If a player has a good pre-AB routing going that gets him focused, then go get ‘em.

Bottom line for me is that getting ready with your game bat immediately before getting in the box (ie. on deck) appears to make the most sense.  If you want to take some cuts with the heavy bat, that’s fine, but get loose and then move on so you at least have a couple of swings with the regular bat.  And don’t forget to watch the pitcher!

Jeff Bat Speed, Training research bat speed, biomechanics, research