Science of Baseball: Best Way to Warm Up on Deck

Effects of Various Warm-Up Devices and Rest Period Lengths on Batting Velocity and Acceleration of Intercollegiate Baseball Players
Wilson et al.
published ahead of printing Nov 2011
Journal of Strength and Conditioning Research

The basis of this research was to determine how to improve a hitter's ability to make contact on a pitch.  The acknowledge that a batter needs 0.3 seconds to process a pitch and swing at it and leaves only 0.1 seconds for a bat to choose to swing at a pitch or not.  The human body cannot improve upon recognition to a greater degree, so the only way to improve hitting in terms of time is to increase bat speed.  The idea is that by reducing bat speed, you increase the time a time can choose whether to swing or not.

Previous study have looked at warm up devices/approaches and their impact on an individual's batspeed.  A study using high school players tested warm up devices that range in weight from 23 to 51 oz with the greatest bat speed resulting from warming up with bats weighing between 26 and 34 oz (Derenne et al. 1992).  Another study looked at the effect using a doughnut weighing 28 oz on a 34 oz bat.  It result in the change in swing mechanics and a decrease in bat speed (Southard and Groomer, 2003).  A third study found that using a 55 oz bat to warm up resulted in decreased bat speed when using a 31.5 oz. (Montoya et al. 2009).  A final study using different bat devices (a study we discussed earlier this year) found that collegiate baseball players did not have their bat speed altered with any tested approach (Szymanski et al. 2011).

What those previous studies did not investigate was what effect the rest period had between warming up and swinging at a pitch.  They used 16 Division II baseball players.  Players practiced with one of five warm up bats on successive days.  The weights were 23, 30, 34, 38, and 50 oz.  The individuals then swung a 30 oz bat one, two, four, and eight minutes after warming up.  Four metrics were measured: peak velocity, peak acceleration, peak velocity at peak acceleration, and time to reach peak acceleration.  Players would warm up and swing the 30 oz bat.  Have ten minutes of rest.  Then they would warm up with a specific experimental warm up bat and then swing the 30 oz bat.

The results were interesting.  None of the warm up bats affected the players ability to generate bat speed.  This agrees with the other study using collegiate athletes.  It may be that once a player reaches a certain level that warm up devices do not improve or impair bat speed.  However, they did find that the more time the player spent resting between his warm up swings and hitting resulted in greater bat speed.  For example, the lowest bat speed was measured during the warm up period.  The greatest bat speed was measured eight minutes after warming up.  No time period after eight minutes was measured, so it is uncertain when this effect tapers off.  Bat speed increased by 8% between warm up and eight minutes.  Peak velocity at peak acceleration increased by 6%.  Peak acceleration increased by 8%.

This seems to suggest a couple things.  First off, a batter might be more susceptible to higher velocity pitches earlier in the count.  Second, a batter might be best off warming up in the tunnel when he is in the hole.  It may well be that all a batter should be doing on deck is watching the pitcher and lightly stretching.