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Bat design and ball exit velocity in baseball: Implications for player safety

R.L. Nicholls* , B.C. Elliott & K. Miller

University of Western Australia

T h e v e l o c i t y o f a p p r o x i m a t e l y 1 1 % o f a l l l i n e d r i v e s f r o m m e t a l b a t s e x c e e d e d 4 9 m / s , r a n g i n g u p t o a m a x i m u m b a l l e x i t v e l o c i t y o f 5 4 . 0 7 7 m / s . T h i s v a l u e i s a p p r o x i m a t e l y 5 m / s g r e a t e r t h a n t h e m a x i m u m v e l o c i t y a c h i e v e d f r o m t h e w o o d b a t ( 4 9 . 1 1 5 m / s ) . H o w e v e r , a m a x i m u m B B V o f 4 9 . 1 7 m / s f r o m w o o d b a t s w a s r e c o r d e d , w h i c h a g a i n e x c e e d s t h e r e c o m m e n d e d s a f e l i m i t b y 8 m / s ( 1 7 m p h ) . T h i s f i n d i n g i s s u b s t a n t i a t e d b y t h e A p r i l 8 , 2 0 0 1 i n j u r y t o C l e v e l a n d I n d i a n s p i t c h e r S t e v e W o o d a r d , s t r u c k a n d i n j u r e d b y a l i n e d r i v e f r o m a w o o d b a t d u r i n g t h e f i r s t w e e k o f M a j o r L e a g u e c o m p e t i t i o n . H o u s t o n r e l i e f p i t c h e r B i l l y W a g n e r w a s h i t i n t h e h e a d b y a l i n e d r i v e o n J u l y 1 6 , 1 9 9 8 - a b l o w f r o m w h i c h t h e b a l l c a r o m e d i n t o t h e t h i r d - b a s e d u g o u t ( B a u m , 1 9 9 8 ) . S u c h i n c i d e n t s i n d i c a t e t h e i s s u e o f e q u i p m e n t d e s i g n a n d s a f e t y i n b a s e b a l l m a y e x t e n d b e y o n d b a t s t o f a c t o r s i n c l u d i n g t h e e l a s t i c p r o p e r t i e s o f t h e b a l l , t h e d y n a m i c s o f t h e i m p a c t b e t w e e n b a t a n d b a l l , i n c r e a s i n g s i z e a n d s t r e n g t h o f h i t t e r s , t h e d i s t a n c e o f t h e p i t c h e r f r o m t h e b a t t e r a n d p r o t e c t i v e e q u i p m e n t f o r d e f e n s i v e p l a y e r s . T a b l e 4 : M e a n b a l l e x i t v e l o c i t y ( m / s ) f o r w o o d a n d m e t a l b a s e b a l l b a t s ( 0 . 0 1 s a f t e r b a l l c o n t a c t ) .

Bat

Mean ball exit velocity (ms-1)

Metal Wood

43.98 ± 4.95 40.80 ± 4.30

p 0.0257

Conclusions

A clear relationship exists between bat weight distribution and both the orientation and linear velocity of the bat at impact. This has important implications for ball exit velocity and player safety. Reversion to exclusive use of wood bats is not an economically viable solution for non- professional baseball leagues. Current NCAA regulations for metal bats in collegiate play legislate for design features including maximum bat diameter and length-to-weight ratio. All bats must also conform to a maximum BBV of 93 +/- 1 mph when swung at 80 mph by the Baum Hitting Machine. Although specific to these bats and players, the results of this study clearly indicate a certified bat swung by a live hitter may produce BBV exceeding that demonstrated when using the Baum Hitting Machine. On June 12, 1999, the NCAA Baseball Rules Committee announced recommendations that mass distribution regulations be adopted for metal bats, although this legislation remains to be enacted. The results of this research support such recommendations.

References “Researchers release latest catastrophic-injury report” NCAA News June 8, 1998 Adair, R.K. (1994) The Physics of Baseball 2nd edition. Harper Collins, New York

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