Dear Editor,

We appreciate Russell's comments and additional analyses. While there may be minor points where we still disagree, it is clear from Russell's comments that he supports our general hypothesis that there is indeed a safety concern in the sport of slow-pitch softball. We continue to stand by our field-testing research as well as published human response time studies that support our claims that the sport of softball is unsafe and will continue to conduct research studies using human subjects as the ideal metric for predicting safety in the sport of softball and baseball.

Dear Editor,

I was interested to read your recent article in the British Journal of Sports Medicine on a sequential AIIS avulsions in an adolescent long jumper. I have recently had a young patient who was a soccer player, with two sequential avulsions on the right side of the AIIS within a shorter time frame. I would just like to point out, however, that on the xray, especially in Figure 1, it appears as if the injury in your athlete is more to the anterior superior iliac spine (ASIS), where the sartorius muscle attaches. In fact, it is identified as this in the caption for Figure 1, but not for the other Figures. I have also seen avulsion injuries to the superior part of the iliac crest where the gluteus medius muscle attaches.

Sincerely,

Connie Lebrun
Director Primary Care Sport Medicine
Fowler Kennedy Sport Medicine Clinic

I am writing again, not to engage in a war of words with the authors, but to offer some suggestions which might strengthen the safety concerns reached in the paper by McDowell and Ciocco.[1] Unfortunately, it appears that the authors misunderstood the point of my first letter and assumed that I was criticizing their conclusions regarding the safety in slow-pitch softball. I do not disagree with their conclusion that high performance bats present a significant safety risk. My letter attempted to raise three points: (i) that the ASTM 1890 standard which the authors used to define a safe reference APRT from a recommended safe initial BBS" does not accurately predict field performance and therefore should probably not be used to establish a baseline for safety arguments; (ii) that one of the "two major national softball associations in the United States" the authors refer to in their paper has long since abandoned this standard in favor of one which much more accurately predicts field performance of bat, though it does have its own unique problems; and (iii) that I felt the choice of bats used in this study do not represent bats currently used by the majority of those who play recreational softball at the time this paper was finally published.

I will refrain from attempting to refute the authors' professionally offensive claim to be the only researchers capable of "truly independent research" in the area of softball and related performance and safety issues, and I will not respond to their completely unprofessional attacks on my own integrity and research ethics. I would, however, appreciate the opportunity to respond to their challenge to "present published batted-ball speed testing results from a truly independent source." I have to admit I'm not entirely sure I understand what McDowell and Ciocco consider to qualify as a "truly independent source." I am, however, aware of a very thoroughly conducted field study comparing wood and metal baseball bats which resulted in several publications.[2-4] This field study, which used 19 players from high school, college and minor leagues, had hitters swinging at pitched balls with six different metal bats and one wood bat. Multiple high-speed video cameras were used to measure the trajectories of the ball and bat before and after the collision. The study found that metal bats can significantly outperform wood bats and the various published papers provide a wealth of information that could be used to derive APRT values and other data regarding the safety of the game. This study does not directly satisfy the challenge because it deals with baseball bats, not slow-pitch softball bats. However, it is an excellent example of how a proper field study should be carried out, both in terms of the experimental methods which guarantee reliability of the data and statistical repeatability of the results. Such an extensive field study is very expensive to conduct and requires external funding to be brought to fruition. Unfortunately I would guess that such external funding, in this case from the SGMA and NCAA, is what might disqualify this field study from being considered "truly independent research." I am also aware of two field studies concerning men's slow pitch softball, one conducted in Montgomery in 2001 and the other in Charlotte in 2002, which have not yet been published because the researchers are still in the process of analyzing several hundreds of gigabytes of high speed video footage from multiple cameras which were used to record the motion of the bat and ball in 3-D. These two studies were also conducted with a high degree of attention to detail and thoroughness in experimental procedure. I hope these studies will be published in the very near future, as they will provide much needed information on the performance and safety of bats in slow-pitch softball. However, these studies will also probably not count as "truly independent research" since they were funded, at least in part, by the ASA.

I am also aware of a relevant paper by Robert Adair [5] which addresses issues regarding the safety of slow-pitch softball and pitcher reaction times remarkably similar to those raised by McDowell and Ciocco. Adair's paper was published in 1997, long before high performance composite bats, and yet he was able to predict the dangerous impact such bats might have on the game. Adair doesn't use the term "available pitcher reaction time" but he does show similar data for reaction times and comes to the same conclusion that elastic polyurethane softballs hit with high performance softball bats do not allow the pitcher enough time to react to a line drive, and thus present a safety hazard to the game of softball. Adair's paper also raises two additional points regarding safety which are easily verified through a simple computer calculation. I would like to share these points with McDowell and Ciocco because it would make the arguments for safety in their paper much stronger. The calculation plots the trajectory of a softball leaving the bat at a height of 0.8 m above home plate, and with an initial angle of 6.0 degrees above the horizontal so that it follows a line drive path towards the pitcher who is standing 15.24 m away. The effects of air resistance are included during the entire path of the ball using the approach by Giordano [6] which accounts for the fact that air resistance depends on the square of the ball speed, and thus continuously changes during the ball's flight. This results in slightly different APRT values from those reported by McDowell and Ciocco since they used a single constant air drag reduction to obtain an average ball speed for all cases. For the discussion below I use an initial batted ball speed for a composite bat of 167.6 km/h which was extracted from Table 2 of the McDowell and Ciocco paper by removing the constant air drag factor. I compared this calculation with that for a "recommended safe initial BBS of 137.2 km/h." The results of this simple calculation are as follows:

• The ball hit by the "safe" bat with BBSi = 137.2 km/h = 38.1 m/s = 85.3 mph arrives at the pitcher in a time of APRT = 0.420s, while the ball hit by the composite bat with BBSi = 167.6 km/h = 46.55 m/s = 104.1 mph arrives at the pitcher in a much shorter time of APRT = 0.350s. My calculated APRT is shorter than that of McDowell and Ciocco due to our different treatments of air resistance. It would appear that correctly accounting for air resistance makes the safety issue even more pronounced. In any case, as expected, the pitcher will have significantly less time to react to the ball hit by the composite bat.
• More importantly, perhaps, are the speeds of the balls when they reach the pitcher. The ball hit by the safe bat will be travelling at 35.3 m/s (78.9 mph) when it hits the pitcher, whereas the ball hit by the composite bat will still be travelling with a speed of 43.2 m/s (96.6 mph) when it hits the pitcher. Both hit balls have lost a significant fraction of their initial velocity due to air friction, but the ball from the composite bat is still travelling at a very dangerous speed when it reaches the pitcher. This faster speed means more momentum and more kinetic energy goes into the collision with the pitcher's body. Furthermore, since the COR of the ball decreases as ball speed increases, the higher ball speed also means that the ball will behave less elastically when it hits the pitcher. It should be no surprise that when players are hit by balls from high performance metal and composite bats, the injuries are more severe then they might have been from a ball hit by a "safe" bat.
• Thirdly, this simple calculation shows that when the ball from the safe bat arrives at the pitcher's mound it will be 1.55 m (5.08 ft) above the ground. However, the ball hit by the composite bat will be 1.83 m (5.99 ft) above the ground when it reaches the pitcher. This is very important because it means that while the ball from the safe bat might hit the pitcher in the chest or shoulder, the ball from the composite bat (which is already arriving with a much faster speed in a shorter time) will strike the pitcher in the neck or face. A pitcher might be able to get his glove up to chest level in time, but would probably not be able to move it the additional 11 inches up to face level fast enough to intercept the ball hit by the composite bat.

In the final paragraph of their paper, McDowell and Ciocco state that the "use of lower compression balls may greatly reduce BBSs and allow the pitcher enough time to react to most batted balls." While I would agree with this statement, the data presented in Table 1 of their paper does not appear to support this conclusion as strongly as they state. If one looks at the data in Table 1, one finds that lowering the compression of the ball from 2371 N/.64cm (529 lb/in) to 1668 N/.64cm (372 lb/in) while keeping the COR constant at 0.47 only reduces the batted ball speed by 1.77 km/h (1.1 mph). This is not a significant reduction in BBS, and the corresponding APRT only increases by 0.005s, which does not seem significant enough to improve the safety of the pitcher. This reduction in BBS is also much less than the reduction in BBS of 4.67 km/h (2.9mph) which was measured during a field study of slow-pitch softball conducted in 2002, and to be published soon. In addition, according to the data in Table 1, one fines that a reduction in the COR from 0.47 to 0.40 while keeping the compression relatively constant (2371 vs. 2460) actually causes the batted ball speed to increase by 1.29 km/h (0.8mph). This completely contradicts what one would expect from a simple physics analysis of the ball-bat collision. Furthermore, is contradicts data from another slow-pitch field study, unfortunately also not yet published, which showed that lowering the COR by the same amount with the same constant compression actually lowered the BBS by 7.89 km/h (4.9 mph). Any one who has played softball with balls of varying compression and COR knows from direct experience that changing the ball properties has a significant effect on the resulting batted ball speed. The data in this paper not only fails to agree with other, unfortunately yet unpublished, field studies, but it also contradicts what players (as well as manufacturers and associations) know actually happens in the field. While McDowell and Ciocco are right in their recommendation that lowering ball compression and COR might make the game safer, the data as presented in this paper does not back up their recommendation, suggesting that perhaps a more accurate method of measuring batted ball speed should be implemented in future studies.

I have one final comment with regards to the authors' comments on the validity of field studies compared to laboratory tests. A serious potential problem with field studies is that the results depend very much on the caliber and ability of the players who participate in the study. This potential variation in skill between players is absent from a carefully controlled laboratory experiment. This issue is especially important if one is trying to draw conclusions concerning the safety of certain bats and one wishes to separate the performance qualities of the bat from the performance skill of the players who swing the bat. Here's an example of what I mean. I play recreational softball in a summer church league. We have a big, tall player on our team who played baseball in college 25 years ago. He uses a 32oz, single-walled aluminum bat (he says the newer high-tech composite bats feel too light), and yet, almost every time he steps up to the plate he routinely punches the ball over the center field wall, more than 300 feet away. If this individual had participated in the McDowell and Ciocco study his mean BBS values for the aluminum single-wall bat would far exceed the 134.0 km/h reported in Table 2, and would probably approach values for Titanium and composite bats. Furthermore, the APRT for a line drive from this player using his single-walled bat would be much shorter than the 0.409s reported for a single-walled bat in Table 3. I'm reminded of the 1980's slowpitch giant Carl Rose, who routinely hit softballs over 400 ft using a singlewall aluminum bat, and embarked on a quest to hit a softball out of every major league baseball field using a single-walled aluminum bat. A limitation of field studies is that they rely too much on the ability of the players who participate in the test, and require a relatively large number of players to ensure statistical reliability of the data. I would agree that as long as one is using "average" players and very carefully define what it means to be a player of "average" ability, then the point McDowell and Ciocco are making is valid. That is, high performance composite bats in the hands of an "average" player present a safety hazard to the game. However, a low performance single-wall aluminum bat in the hands of a high performance player also presents a safety hazard to the game, which the field study described in this paper does not account for.

The reason for a standardized laboratory test, such as ASTM F1890 or ASTM 2219 is to provide a way to measure the performance of bats in an accurate and repeatable manner without the variation introduced by the human element. Granted it is absolutely necessary to attempt to correlate the laboratory results with field studies to make sure the laboratory results fall within the range of performances measured by players in the field. As I attempted to explain in my first letter, F1890 completely fails in this regard. In contrast, while F2219 was being developed the laboratory results were correlated with field trials for the highest performing A and B-level players at two different national ASA tournaments. As such, the performance data obtained in the laboratory with F2219 attempts to predict the performance of a bat in the hands of some of the best human players currently playing the game. While F2219 does a much better job of predicting field performance, it is by no means a perfect standard and has its own unique set of flaws. Hopefully through persistent research some of these problems may be eventually resolved. I believe that any laboratory test which more closely predicts actual field performance of bats must be welcomed as a useful tool to ensure the safety and integrity of the game. Of course, if manufacturers chose to take advantage of loopholes (as they are currently doing) and if associations refuse to adopt the more accurate standard (like 5 of the six US softball associations have) and if those associations that do adopt the better test method don't use it correctly (by setting too high a limit or by grandfathering in dangerous bats) then the usefulness of the test method has been greatly diminished and the safety of the game is still in jeopardy.

Safety in the sport of softball is a very important issue. Is it vital that research which addresses this issue of safety be carried out in a professional manner with considerable attention to detail in the experimental process and diligent analysis of the data so that the reported results and conclusions are as accurate and relevant as possible.

These comments are respectfully submitted by

Daniel A. Russell, Ph.D.
Associate Professor of Applied Physics
Kettering University, Flint, MI

References
[1] M. McDowell and M. V. Ciocco, "A controlled study on batted ball speed and available pitcher reaction time in slowpitch softball," Br. J. Sports Med., 39, 223-225 (2005).
[2] J. Crisco, R. Greenwald, L. Penna, and K. Saul, "On measuring the performance of wood baseball bats," Engineering of Sport - Research Development and Innovation, Edited by A. Subic and S. Haake, p.193-200 (Blackwell Science, Oxford, 2000).
[3] R. M. Greenwald, L. H. Penna, and J. J. Crisco, "Differences in Batted Ball Speed with Wood and Aluminum Baseball Bats: A Batting Cage Study," J. Appl. Biomech., 17, 241-252 (2001)
[4] J.J. Crisco, R.M. Greenwald, J.D. Blume, & L.H. Penna, "Batting performance of wood and metal baseball bats," Med. Sci. Sports Exerc., 34(10), 1675-1684 (2002)
[5] R.K. Adair, "The Physics of Baseball: The Standardization of Balls and Bats for Recreational Softball," International Symposium on Safety in Baseball and Softball, ASTM STP 1313, Earl. F. Hoerner and Francis A. Cosgrove, Eds., p. 21-28 (American Society for Testing and Materials, 1997).
[6] N. J. Giordano, Computational Physics, (Prentice Hall, 1997), p.23-32.

Dear Editor,

We would like to thank Russell for his letter because we feel the subject of safety in the sport of men’s slow-pitch softball has been ignored for too long and it is refreshing to see that others are also taking notice. An increase in the awareness of this subject through discussions and scientific publications will help lead to required, well-defined, safety standards in the sport of softball. Unfortunately, we take issue with some of Russell’s comments.

The comments by Russell about publishing this paper in an American journal are without merit. The BJSM is an excellent Journal that is truly concerned with sports safety. Suggesting or implying that BJSM’s review process or standards are sub par compared to American Journals is completely unwarranted.

Russell’s comments on outdated performance standards are misleading. At the time this paper was prepared the performance standards mentioned in the paper were in use. The ASTM F2219 standard that he mentioned was adopted by the ASA association on January 1st, 2004. In addition, it takes time for a peer review article to be published. We are well aware of the recent changes in laboratory performance-based testing. In terms of the sports of softball and baseball, the ASTM is a laboratory performance- based organization, not a safety-based organization. We are primarily concerned with safety studies, not laboratory performance standards since actual field-test studies are the only true test of player safety. We feel using human reaction time studies and research will lead to a truly safe sport for the recreational softball player.

The following is attached to each scope section 1.4 with every ASTM performance standard in the sports of softball and baseball; “This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use”.

Based on this fact, Russell’s comments on the use of ASTM standards are not sufficient to rely on as a safety standard for the sport of softball or baseball. Again, our primary focus is on the safety aspect of the sport of slow-pitch softball, not comparisons and evaluations of the various ASTM laboratory performance standards used by the different softball associations. There are some important points not mentioned by Russell that need to be addressed concerning the new ASTM performance standard, ASTM F2219. Only one of the at least six (6) slow-pitch associations in the United States are currently using ASTM standard F2219. In addition, it still remains a laboratory performance-based test which has its shortcomings compared to real-world field-tests. One very obvious loophole in the ASTM F2219 test is already being exploited by bat manufacturers to produce bats that pass the “98 mph (43.8 m/s) limit” but perform above this limit in real-world conditions.

It should also be mentioned that the ASA, despite claiming to adopt the ASTM F2219 with a 98 mph (43.8 m/s) limit, still allows bats that surpass the limit to be used. These “grandfathered” bats include the Miken Freak, Mizuno Crush, Easton Synergy 2, etc. We realize the associations may be under a lot of pressure not to ban bats, but it appears that safety is being compromised in this case. Attend any ASA sponsored tournament and you will see that most teams are using these “grandfathered” bats because they out perform other ASA bats. The end result is that the ASTM F2219 with a 98 mph (43.8 m/s) limit is not even being incorporated into the game today.

There have been a few important safety studies in the sport of baseball that Russell failed to mention. A safety study by Owings, et al.,[1] investigated pitcher reaction time as a consideration in design constraints for baseballs and baseball bats for various age groups. They found that for the 16-year age group, a minimum reaction time of 0.409 sec. was necessary to reduce the potential for serious or catastrophic injury. Accounting for ball deceleration, the maximum initial batted-ball speed to allow 0.409 sec. is 39.1 m/s. While, as Russell points out “The ASA has set a maximum Batted-Ball Speed limit of 43.8 m/s (157.7 km/h) using the high-speed impact test F2219”, this equates to an available pitcher reaction time of only 0.365 sec, which is clearly a significant safety concern. We are basing our conclusions on published, peer reviewed literature that at least 0.409 sec. is needed for a player to determine, decide, and react to a batted-ball[1].

Another study initiated by the NCAA tested a variety of bats on a specially designed batting machine located at the University of Massachusetts in Lowell[2]. The recommendation based on this research effort was to drop the exit speed of a batted-ball to no more than 149.7 km/h (93 mph) in collegiate baseball. In this case this equates to an available reaction time of 0.420 sec. Again, the 0.365 sec. the ASA believes is “safe” is much less and illustrates the significant safety concern.

A recent review article by Nicholls, et al.,[3] investigates the current literature relating to impact injuries and the role of equipment performance in the sport of baseball. They surmise that batted-ball speeds from non-wood bats can reach velocities potentially lethal to defensive players. Another study by Nicholls, et al.,[4] compared ball exit velocity between metal and wooden baseball bats. The results of this study indicate that a “certified” metal bat swung by an experienced hitter can produce ball exit velocities exceeding that demonstrated by a robotic hitting machine, which is what is currently used in the sport to determine bat safety. This illustrates the necessity for field-testing research.

The published literature on pitcher reaction time consistently supports our claim that the sport is much too dangerous for the recreational player and we stand by our research findings. Obviously the only fatal (literally) flaw here is to trust the various softball associations to set safety standards. An independent organization needs to set one comprehensive safety standard for the entire sport of Slow-Pitch Softball.

Russell’s comments on illegal and banned bats are again, misleading. We used titanium bats as a reference due to the fact that they were outlawed immediately by their excessive batted-ball speeds. Today’s composite bats produce batted-balls speeds in excess of titanium bats but have been in use for the past five years. Our field-test studies indicate that today’s high-tech composite bats consistently outperform titanium and aluminium bats yet there are still allowed to be used. The real question is: Why are bats that consistently outperform the banned Titanium bats legal for play in some associations today?

As for the comment that this study would have been relevant 5 years ago, the fact is this study would have been impossible 5 years ago because neither the Synergy nor the Ultra II were introduced until 2003. Furthermore, at the time of this study, these bats were legal and still are legal in some associations. For example the Synergy is still legal in USSSA and SSUSA play and the Ultra II is still legal in SSUSA play.

Obviously, as with most research, there are still many questions to be answered and we are continuing our field-testing research studies of slow-pitch softball equipment in order to improve the safety of the game. Along these lines we have another field-testing research study, soon to be published, that also indicates that there is a significant safety risk to slow-pitch softball pitchers. From Owings published results[1], at least 0.409 sec. was deemed necessary to reduce the potential for serious or catastrophic injury. Below is a subset of the data in this upcoming paper. The initial batted-ball speeds (BBSi) and the available pitcher reaction times (APRT) are listed for all softball associations ASA/USSSA/NSA/ISA/SSUSA and ISF legal non-composite and composite bats.

Non-Composite ASA 2005 Model Bat: BSSi = 45.5 m/s, APRT = 0.351 sec.

Non-Composite USSSA/NSA/ISA/SSUSA/ISF 2005 Model Bat: BBSi = 45.5 m/s, APRT = 0.351 sec.

Composite ASA 2005 Model Bat: BBSi = 45.0 m/s, APRT = 0.355 sec.

Composite USSSA/ISA/NSA/SSUSA 2005 Model Bat: BBSi = 47.4 m/s, APRT = 0.338 sec.

Wooden bat (Reference): BBSi = 38.0 m/s, APRT = 0.421 sec.

The results indicate that there still exists a serious safety issue that has not been addressed by the softball associations. To that end, we are continuing our field-testing research efforts and hope that one day soon a uniform safety standard will be applied to the sport, which we feel will ultimately reduce serious and catastrophic injures as well as fatalities that have occurred in the sport over the past few years. The authors are only concerned with the safety of the game of softball and having one uniform safety standard for the entire sport of slow-pitch softball.

In closing, we challenge Russell to present published batted-ball speed testing results from a truly independent source. He failed to disclose that he has a conflict of interest when it comes to the laboratory testing of softball bats by being affiliated directly or indirectly with at least one softball association, hence his repeated references to a new ASTM standard that has been adopted by only one softball association. The authors of this study have no, nor are seeking an affiliation with any bat or ball manufacturer or softball association and conduct truly independent field-testing research on softball and baseball bats and balls free from outside influence. The same cannot be said of Russell and his colleagues who appear to be actively engaged in discussions with bat manufactures concerning laboratory testing of softball bats.

References

1. Owings, T. M., Lancianese, S. L., Lampe, E. M., and Grabiner, M. D. (2003) Influence of Ball Velocity, Attention, and Age on Response Time for a Simulated Catch. Medicine & Science in Sports and Exercise. Vol. 35, No. 8, pp. 1397-1405.

2. Mississippi State University (2002). Study helps give pitchers more time to react. University Relations News Bureau. URL: http://msuinfo.ur.msstate.edu/msu_memo/1999/02-08-99/bats.htm.

3. Nicholls, R.L., Miller, K., Elliott, B.C. (2004) Review: Impact injuries in baseball: prevalence, aetiology and the role of equipment performance. Sports Medicine 34(1): 17-25.

4. Nicholls, R.L., Elliott, B.C., Miller, K., Koh, M. (2003) Bat kinematics in baseball: implications for ball exit velocity and player safety. Journal of Applied Biomechanics 19: 283-294.

5. McDowell, M, Ciocco, M. and Morreale, B. (2005). "A Composite Softball Bat Revolution: Why the Pitcher has Little Time to React to a Batted-Ball". The Sport Journal Vol. 8(1).

6. McDowell, M. (2004). "Assessment of Softball Bat Safety Performance Using Mid-Compression Polyurethane Softballs". Sports Biomechanics Vol. 3(2) 185-194.