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Effect of Various Warm-Up Devices on Bat Velocity of Intercollegiate Baseball Players

Szymanski, David J; Beiser, Erik J; Bassett, Kylie E; Till, Megan E; Medlin, Greg L; Beam, Jason R; DeRenne, Coop

Journal of Strength and Conditioning Research: February 2011 - Volume 25 - Issue 2 - p 287-292
doi: 10.1519/JSC.0b013e318202e31e
Original Research
Press Release

Szymanski, DJ, Beiser, EJ, Bassett, KE, Till, ME, Medlin, GL, Beam, JR, and DeRenne, C. Effect of various warm-up devices on bat velocity of intercollegiate baseball players. J Strength Cond Res 25(2): 287-292, 2011-A variety of warm-up devices are available to baseball players to use before their game at-bat. Past baseball research evaluating warm-up devices indicates that implements that are ±12% of standard game bat weight produce the greatest bat velocities for high school and intercollegiate players. The purpose of this study was to examine the effect of various warm-up devices on bat velocity (BV) of intercollegiate baseball players. Twenty-two Division I intercollegiate baseball players (age = 20.0 ± 1.5 years, height = 182.6 ± 8.3 cm, body mass = 91.4 ± 11.4 kg, lean body mass = 78.8 ± 8.9 kg, % body fat = 13.6 ± 3.8) participated in a warm-up with 1 of 10 weighted devices on separate days. Each of the 10 testing sessions consisted of a standardized warm-up, 3 dry swings as hard as possible with the assigned warm-up device, 2 comfortable dry swings with a standard game baseball bat followed by 3 game swings (20-second rest between swings) while hitting a baseball off of a batting tee with the same standard game baseball bat. Results indicated that there were no statistically significant differences in BV after using any of the 10 warm-up devices. For male intercollegiate baseball players, results indicate that warm-up devices varying from 623.7 to 2,721.5 g (22-96 oz.) did not change mean BV of a standard game baseball bat, suggesting that intercollegiate players can use any of the 10 warm-up devices in the on-deck circle and maintain their BV. Therefore, personal preference as to which warm-up implement to use in the on-deck circle is advised.

1Department of Kinesiology, Louisiana Tech University, Ruston, Louisiana; 2Department of Health, Exercise, and Sports Science, University of New Mexico, Albuquerque, New Mexico; and 3Department of Kinesiology and Leisure Science, University of Hawaii at Manoa, Manoa, Hawaii

Address correspondence to Dr. David J. Szymanski,

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It has been reported that bat velocity (BV) is an important component for successful hitting (3,6,14). Baseball players from Little League to Major League Baseball traditionally swing weighted devices in the on-deck circle to warm-up before stepping into the batter's box to hit. The type of warm-up device used in the on-deck circle varies. Today, amateur and professional baseball players commonly use a 453.6 g (16 oz.) donut ring or 680.4 g (24 oz.) Pow'r Wrap added to their game bat, or a 2,721.5 g (96 oz.) Schutt Dirx warm-up bat. The idea is that swinging a heavy warm-up device in the on-deck circle will increase players' BV with their game bat when attempting to hit the baseball during an at-bat. If BV is increased, this will allow the batted-ball exit velocity to be greater, the baseball to be hit farther, or both (1,14). If a warm-up device(s) can produce optimal results (greater BV) as one swings at a pitched baseball in the batter's box to hit, then a player's performance (batting average, home runs, slugging percentage) could be improved.

Southard and Groomer (17) stated that “perceptual distortion of movement as a result of experience with a previous object is the crux of experimental designs in which bat weight was manipulated to determine the effect on bat speed. Such perceptual distortion is referred to as kinesthetic aftereffect.” Although the number of studies involving kinesthetic aftereffect with baseball have been increasing, it needs to be mentioned that research on kinesthetic aftereffect after practice with a weighted object has been previously reported. Lindeburg and Hewitt (10) investigated the effect of training with an oversized basketball on ball handling and shooting. Their results indicated that performance was not improved even though subjects reported a perception of increased ball handling ability. Stockholm and Nelson (18) examined the effects of weighted vests on jumping performance. Subjects jumped with weighted vests then jumped without weighted vests. They reported no improvement in jumping performance. Nelson and Nofsinger (12) evaluated speed of elbow flexion before and after applying weights to the arm. They reported no difference in speed, but the subjects stated that they experienced the kinesthetic aftereffect of “feeling faster.”

However, previous baseball research by DeRenne et al.s has shown that warm-up with implements weighing between 765.4 and 963.9 g (27 and 34 oz.) produced the greatest BV for high school (6) and intercollegiate, ex-college, and professional (4,5) baseball players when swinging a 83.8 cm, 850.5 g (33 in, 30 oz.) “standard” game baseball bat. Furthermore, this research has indicated that very heavy (>1,190.7 g or 42 oz.), very light (<765.4 g or 27 oz.), and implements added on (donut ring, Power Sleeve, Power Swing) to the 83.8 cm, 850.5 g (33 in, 30 oz.) “standard” game bat have had the most adverse effect on BV (4-6). This research suggests that there is a specific percentage of the standard implement weight (±12%) that produces the most positive effects on BV. Research by Southard and Groomer (17) indicated that swinging an 83.8 cm, 963.9 g (33 in., 34 oz.: “standard”) bat or an 83.8 cm, 340.2 g (33 in., 12 oz.: “light”) bat in the on-deck circle produced faster BV than an 83.8 cm, 1,587.5 g (33 in., 56 oz.: “heavy”) bat. Montoya et al. (11) reported results similar to those of Southard and Groomer (17). Their findings indicated that players should swing either a “light” (272.2 g or 9.6 oz.) or “normal” (893 g or 31.5 oz.) bat in the on-deck circle as a warm-up device because they both produced faster BV than a “heavy” (1,564.9 g or 55.2 oz.) bat. Both of these studies indicated that swinging a very light implement in the on-deck circle produced greater BV with a game bat than swinging a heavy implement as a warm-up device. There has also been research that has demonstrated that heavier implements (>1,445.8 g or 51 oz.) than a 33 in., 30 oz. (13), 31.5 oz. (9), or 32 oz. (8) game bat do not produce the greatest BV but do provide the “kinesthetic illusion” of greater velocity regardless of nondifference on BV.

Recently, Reyes and Dolny (15) evaluated the acute effects of various weighted bat warm-up protocols on BV. Nine weighted bat warm-up protocols, using 3 weighted bats (“light, standard, and heavy”) were swung in 3 sets of 6 repetitions in different orders. The results indicated that there was no significant effect on “standard” bat (33 in, 30 oz.) BV using any of the 9 protocols. However, the authors suggested that players use the order of “standard” (850.5 g or 30 oz.), “light” (793.8 g or 28 oz.), and “heavy” (1,530.8 g or 54 oz.) bats in the on-deck circle because this sequence resulted in the greatest increase (6.0%) in BV compared to only swinging the “standard” bat. For clarification to the reader, 5 on-deck circle research studies on BV have used the term “standard” (8,9,17), “normal” (11), or “ordinary” (13) game bat to represent the player's regular game bat, but these bats were heavier than the “standard” game bat used by DeRenne et al. (4-6) and in this study. Therefore, quotes have been placed around the specific words used by the various authors that represent a regular game bat in the Introduction and Discussion sections. For the body of this article, quotes will not be around the word standard that represents the 83.8 cm, 850.5 g (33 in., 30 oz.) baseball bat used in this study.

Because a variety of over and underweighted warm-up implements have produced positive effects on BV, it is not collectively accepted as to which implements produce the greatest BV. So, the question remains, “What kind of device should a baseball player use in the on-deck circle as a warm-up to produce the greatest BV when they step into the batter's box facing a pitcher in a game situation?” In addition to warm-up implements or devices placed on the bat, there are companies that make devices that can be worn by players that claim that their product also increases BV without any research data to support their statements. Therefore, the purpose of this study is to examine the effects of various warm-up devices on BV of intercollegiate baseball players' standard game bat. Based on the results of this study, baseball coaches and players may be able to select a warm-up device that provides the greatest BV.

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Experimental Approach to the Problem

This study was designed to compare the effect of various weighted devices swung in the on-deck circle on baseball BV with a 83.8 cm, 850.5 g (33 in., 30 oz.) standard aluminum baseball game bat. Previous research by DeRenne et al. has indicated that this size and mass of the baseball bat are standard to (regularly used by) intercollegiate baseball players (4-6). Twenty-two intercollegiate baseball players participated in 10 separate testing sessions where they randomly swung a different warm-up device that ranged from 623.7 g to 2,721.5 g (22-96 oz.) each session. A single-factor (BV) within-subject design with 10 levels was implemented to see if any of the weighted devices positively or negatively affected BV. To accomplish this, BV was measured and recorded to determine the acute effect of the warm-up device.

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Twenty-two male Division I intercollegiate baseball players (mean ± SD, age = 20.0 ± 1.5 years, height = 182.6 ± 8.3 cm, body mass = 91.4 ± 11.4 kg, lean body mass = 78.8 ± 8.9 kg, percent body fat = 13.6 ± 3.8, playing experience = 15.0 ± 1.5 years) volunteered to be in this study. Only players that the college baseball coaching staff expected to hit (position and dual players) were involved in this study. Dual players play a position and pitch. An Institution Review Board approved the study for human subjects and written informed consent was obtained from each subject before any testing.

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Instantaneous BV was measured by a SETPRO SPRT5A chronograph (SETPRO, Westbrook, CT, USA) and recorded in meters per second (Figure 1). This device provided instant feedback concerning BV (16) and has been used in previous research (7,19-21). The chronograph is no larger than a small alarm clock. There are 2 sensors (A and B) placed 10.16 cm (4 in.) apart. The sensors pick up reflective tape placed on the end cap of the test bat. The sensors are 1.27 cm (0.5 in.) in diameter. The optical system was designed to extract a midpoint from the entire duration of time the reflective tape appeared in the sensor. For example, sensor A would start the timer based on the midpoint in time from which it could “see” the reflective tape. Then, the timer was stopped based upon the value from which sensor B calculated as the midpoint of “seeing” the reflective tape.

Figure 1

Figure 1

For optimal use, the chronograph was placed 55.88 cm (22 in.) from the batting tee where the bat would be coming through the zone of the 2 sensors. Best efforts were made to align the chronograph properly, but varying types of swings (slice angle) can affect the chronograph's reliability. For example, if a player's swing comes in at a steep slice-angle, one of the sensors may not be able to “read” the reflective tape on the bat end for the full duration that it is able to read a swing travels cleanly through the sensors. So, every effort was made to measure accurate BV. A qualitative judgment was made by the principal investigator so as to include only level swings in the analysis. Therefore, it is reasonable to assume that slice angle had a negligible effect on the results of this study. Additionally, each day before testing the players, the principal investigator had his BV tested for reliability. Mean test-retest reliability of the mean BV of 6 test swings for 10 days was r > 0.92. According to the manufacturer, the unit is calibrated with a crystal source and radar to ensure accuracy.

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All players were medically cleared by the university athletic training staff before being involved in this study. This was provided by the university before athletes could participate in National Collegiate Athletic Association athletics. During the initial session, participants answered a modified Physical Activity Readiness Questionnaire (PAR-Q) to assess their health. If they progressed through the athletic training and PAR-Q screenings, they were considered healthy to participate in this study. Participants also completed a Descriptive Data Questionnaire, designed by the principal investigator, which described their playing and exercising experiences. The procedure for testing BV and the various warm-up devices used in this study were verbally explained and demonstrated to the participants by the prinicipal investigator.

After the initial session, subjects were randomly placed into 1 of 10 groups to swing the 10 different warm-up devices. Groups 1-8 had 2 subjects in each, whereas groups 9 and 10 had 3 subjects in each. Each group participated in 1 session per day over 10 days during the off season. The order of experimental session (warm-up device used) was counterbalanced across groups. This means that each day each group swung a different warm-up device until all devices were tested. All devices were used by 1 group each testing session. The testing took place over 12 days because no testing was performed on the weekend. Proper bat swings were demonstrated and verbally explained by the principal investigator who was a former intercollegiate baseball player and coach.

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Warm-Up Devices

The 10 different warm-up devices used in this study were a 83.8 cm, 850.5 g (33 in, 30 oz.) standard aluminum baseball game bat, 7 overweighted devices that included the Pitcher's Nightmare Swing Trainer (resistance tubing device worn between the back leg and back arm while swinging standard game bat), 86.4 cm, 2,721.5 g (34 in., 96 oz.) Schutt Dirx warm-up bat with an adjustable weight located in the middle of the device, 708.7 g (25 oz.) Draz weighted batting gloves (totaling 1,417.5 g) while swinging a standard game bat, 680.4 g (24 oz.) Pow'r Wrap (added to standard game bat; total weight = 1,530.9 g), 453.6 g (16 oz.) donut ring (added to standard game bat; total weight = 1,304.1 g), 396.9 g (14 oz.) Power Fins (air resisted device added to standard game bat; total weight = 1,247.4 g), 83.8 cm, 963.9 g (33 in., 34 oz.) wood bat; 2 underweighted bats that included a 83.8 cm, 737.1 g (33 in., 26 oz.) aluminum bat, and 88.9 cm, 623.7 g (35 in., 22 oz.) aluminum fungo bat. The reason for using such a wide variety of warm-up devices was to include implements commonly used by baseball players and in previous research (4-6,8,9,11,15,17).

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Warm-Up and Testing Protocols

A standardized warm-up procedure, reported in previous research (4,6), was followed by all subjects for each experimental trial. These procedures included having the players perform overhead and behind the back stretching exercises with each warm-up device for 1 minute like players commonly do in the on-deck circle during an actual game. The subjects were then instructed to swing the warm-up device 3 consecutive times as fast as possible in their respective batting motion. Immediately after the warm-up swings, players walked 3 m (10 ft) to the simulated batter's box. Once in the batter's box, players swung the 83.8 cm, 850.5 g (33 in., 30 oz.) standard game bat 2 times in a way that was “comfortable for them” before the experimental trial. Players had to complete the walk and the 2 “comfortable” swings within 20 seconds. For the experimental trial (swing), the subjects were positioned perpendicular to the SETPRO SPRT5A chronograph in their normal batting stance. The subjects were instructed to swing 3 times, attempting to generate maximum velocity while hitting a baseball off of a batting tee that was aligned with their pubic arch (a location that represented a pitch in the middle of their strike zone). To simulate a normal game batting situation, a 20-second rest period was given between each swing with players standing idly in the batter's box before the next experimental swing. However, the subjects were not allowed to practice swinging between trials. The testing order for the 10 different warm-up devices was assigned randomly to each group. Each subject was tested on 10 days, using 1 warm-up device per day.

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Statistical Analyses

SPSS (version 11.5; SPSS, Inc., Chicago, IL, USA) was used for the statistical analysis. A 1-way repeated measures analysis of variance (ANOVA) was conducted on the 3 BV for each warm-up device to see if there were statistical differences between the BV of each swing. In addition, a 1-way repeated measures ANOVA was conducted on the mean BV of the 10 warm-up devices to see if there were statistical differences between the mean BV of each warm-up device. The overall alpha level was set at p ≤ 0.05 for all analyses.

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The ANOVAs indicated that there were no significant differences in BV between the 3 swings (trials) with the standard game bat after using the same warm-up device. Therefore, the mean BV of the 3 trials with the standard game bat was used to represent each condition (Table 1). The test-retest reliability between swing trials for all players averaged 0.89. Power computations revealed a 0.42 score, with a relatively large effect size of 0.852. There was no overall significant difference between the mean BV after swinging any of the 10 warm-up devices, F(9, 189) = 0.852, p = 0.569. Therefore, pairwise comparisons were not conducted.

Table 1

Table 1

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There were no statistically significant differences in mean BV after using any of the 10 warm-up devices. For Division I male intercollegiate baseball players, these results suggest that warm-up devices varying from 623.7 to 2,721.5 g (22-96 oz.) did not significantly change mean BV of an 83.8 cm, 850.5 g (33 in., 30 oz.) standard game baseball bat. These results statistically differ from those of previous research where weighted bats ±12% of standard game bat weight demonstrated the greatest BV (4-6) and others where “light” and “normal” bats (11), “underweighted” and “standard” bats (17), or an “ordinary” bat (13) produced faster BV than heavier bats. However, the warm-up protocol and swing sequence were very similar to the one used by DeRenne et al. (6) with a similar range of weighted warm-up devices. Two notable differences between this study and that of DeRenne et al. (6) were the level of play and ages of the subjects, and the equipment used to measure BV. This study had intercollegiate baseball players with a mean age of 20.0 ± 1.5 years, whereas DeRenne et al. (6) used high school baseball players between the ages of 16 and 18 years. When looking at the data in Table 1, one will notice that the warm-up devices that produced the greatest BV and the slower BV are almost identical to the results reported by DeRenne et al. (4-6). Maybe if this study had a larger subject population like that of DeRenne et al. (6), significant differences between devices would have occurred. Southard and Groomer (17) stated that the moment of inertia, which is the ease of angular motion of the bat, is a main determinant as to how easy or hard it is to swing a warm-up device. Because the donut ring and Pow'r Wrap are placed toward the distal end of the bat and the Draz weighted gloves are worn on the hands that are at the axis of rotation of the bat, the moment of inertia is severely affected. They suggested that the mass of the warm-up device should be evenly distributed along the warm-up device or be within the ±12% of standard bat weight (17). However, it could also be argued that the older players in this study were more physically mature, stronger athletes with better skills of hitting mechanics. This means that the players in this study had at least ≥2 years of playing baseball and resistance training experience at a higher level. Therefore, the statistically significant differences between the various warm-up devices on BV of high school players that DeRenne et al. (6) reported is not the same for the more mature, physically stronger intercollegiate baseball players in this study. The other studies by DeRenne (4) and DeRenne and Branco (5) did use intercollegiate, ex-college, and professional baseball players as in this study. However, unlike this study, both studies did find significant differences between various warm-up devices on BV similar to those reported by DeRenne et al. (6). The second noticeable difference is that a SETPRO SPRT5 chronograph was used in this study and a photosensing computerized timing unit was used by DeRenne et al. (6) to measure BV. Even though both devices were calibrated to be accurate, the SETPRO SPRT5 chronograph records BV from the end cap of the bat covered with reflective tape as it passes by the 2 horizontal sensors while the photosensing computerized timing unit measures BV as the bat passes through the 2 vertical light beams (generally around the sweet spot of the bat) spaced 10.16 cm [4 in.] apart (6). The BV for the college players in this study ranged between 39.20 and 39.86 m·s−1 (87.71-89.19 mph), whereas the BV for the high school players in the study by DeRenne et al. (6) ranged between 24.5 and 27.1 m·s−1 (54.8-60.6 mph).

The results of this study are statistically similar to those of Reyes and Dolny (15), who used Division III intercollegiate baseball players that swung 9 different combinations of “light” (794 g or 28 oz.), “standard” (850 g or 30 oz.), and “heavy” (1,531 g or 54 oz.) bats over 9 days and did not find 1 weighted bat warm-up protocol that significantly increased “standard” bat BV. Their intent was to investigate whether complex training, where sets of heavier and lighter resistance are alternated to elicit a potential increase in muscle performance, changed BV (2). The idea behind using a heavier set in complex training is that skeletal muscle has been shown to be more explosive after completing near-maximal contractions (2). This was the first study to diversify the warm-up combination in this manner in the on-deck circle before entering the batter's box. Although their (15) protocol of various sequences of weighted bats were interesting, they may not be practical in the on-deck circle during a real game situation because of time. The sequence requires a player to take 3 sets of 6 swings with the various combinations for a total of 18 warm-up swings with 3-5 seconds of rest between swings. Like our results with intercollegiate baseball players, research by Kim and Hinrichs also indicated that there was no significant difference in BV of a “standard” bat after swinging a wiffle bat (113 g or 4 oz.), “standard” bat (909 g or 32 oz.), and “standard” bat with a donut ring (1,477 g or 52 oz.) for 8 male and 5 female subjects between the ages of 22 and 28 years (8), or for 20 competitive high school and intercollegiate baseball players that swung a “standard” bat (885 g or 31 oz.), overweighted arm warm-up (2,327 g or 82 oz.), and “standard” bat with a donut ring (1,452 g or 51 oz.) (9).

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Practical Applications

This study suggests that Division I intercollegiate players interested in having the highest BV during a game at-bat can use any of the 10 implements tested because BVs were not significantly different from one another. Furthermore, heavier warm-up devices (Schutt Dirx, weighted gloves, donut ring, or Pow'r Wrap) did not provide greater BV than the “standard” bat or lighter devices. However, some words of caution may be warranted. Even though it has been reported by previous research (6,8,9,13) that swinging weighted bats heavier than one's “standard” game bat as a warm-up provides a psychological advantage because the “standard” game bat feels lighter, a majority of the research (4-6,11,13,17) has demonstrated that heavy bats, specifically a donut ring added to a “standard” game bat, actually produce slower BV and alter swing mechanics. Therefore, individuals interested in using a warm-up device should keep in mind that over and underweighted bats of ±12% of their “standard” game bat, which are not end loaded (top heavy), have been demonstrated in the literature to consistently produce the greatest BV (4-6). In support of these findings of DeRenne et al., Southard and Groomer (17) reported that using a bat with a larger moment of inertia not only slows down a player's swing but it also changes the batter's swing pattern. This could potentially decrease the chances of hitting successfully. Although not significantly different in this study, it is interesting to see that 2 of the most commonly used warm-up devices used in amateur and professional baseball, the donut ring and Pow'r Wrap, produced slower BV similar to in previous research (4-6,11,13,17). Therefore, it is recommended that baseball players still follow the guidelines of DeRenne et al. (4-6) and swing warm-up bats that are ±12% of their “standard” game bat where the weight of the bat is evenly distributed.

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baseball; on-deck circle; bat speed; power; strength

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