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Correlations Between Physiological Parameters and Performance in Elite Ten-pin Bowlers

Benedict Tan, Abdul Rashid Aziz & Teh Kong Chuan

Sports Medicine and Research Centre, SingaporeSports Council, Singapore.

Tan, B., Aziz, R., & Teh, K.C. (2000). Correlations between physiological parameters and performance in elite ten-pin bowlers. Journal of Science and Medicine in Sport 3 (2): 176-185.

The increasing acceptance of ten-pin bowling as a sport, as well as the keen competition amongst bowlers, necessitates the identification of performance indicators to aid training. The aim of this cross-sectional study was to determine if age, height, weight, aerobic power index, bowling glip strength, 1O-RM leg press performance, and the sit- and-reach distance correlated with bowling performance in 42 elite bowlers (26 males and 16 females). At the same time, the physiological profiles of bowlers classified as heavy ball strokers, hea W ball crankers, and light bali spinners were compared. The results showed that for the male bowlers, none of the parameters correlated with performance; while for the female bowlers, the only paralneter that correlated with perlbrmance was the aerobic power index. Bowlers using the three different releases bad similar anthropometl-ic mid physiological profiles. The implications from this stud), are that bowlers of diverse age and build can be equally competitive in the sport; that aerobic capacity {as reflected by the aerobic power index) may, to a certain extent, contribute to bowling Performaalce; and that strength mad fle:dbility measures do not seem to be useful performmlce indicators amongst elite bowlers.

I n t r o d u c t i o n W i t h a n e s t i m a t e d s e v e n t y - o n e m i l l i o n A m e r i c a n s b o w l i n g a t l e a s t o n c e a y e a r , t e n - p i n b o w l i n g i s u n d o u b t e d l y a p o p u l a r s p o r t ( D e B e n e d e t t e , 1991). K e e n c o m p e t i t i o n i s i n e v i t a b l e w i t h s u c h h i g h p a r t i c i p a t i o n r a t e s . T h i s , t o g e t h e r ~vith t h e i n c r e a s i n g a c c e p t a n c e o f b o w l i n g a s a s p o r t r a t h e r t h a n a s o c i a l a c t i v i t y (as e v i d e n c e d b y i t s i n c l u s i o n , for t h e f i r s t t i m e , a s p a r t o f t h e 1 9 9 8 C o m m o n w e a l t h G a m e s ) ; h a s l e d to a d e m a n d for o b j e c t i v e r e s e a r c h to b e c o n d u c t e d w i t h t h e h o p e o f h e l p i n g b o w l e r s i m p r o v e t h e i r p e r f o r m a n c e s . U n f o r t u n a t e l y , o n l y l i m i t e d r e s e a r c h h a s b e e n c o n d u c t e d o n t h e s p o r t to d a t e .

In c o m p e t i t i v e t e n - p i n b o w l i n g , it i s m o s t p r o b a b l e t h a t t e c h n i c a l a n d p s y c h o l o g i c a l s l d l l s ( N e w t o n & D u d a , 1993; T h o m a s e t al., 1996) c o n t r i b u t e t o a c h i e v i n g h i g h s c o r e s . T h e c o n t r i b u t i o n f r o m p h y s i o l o g i c a l c a p a c i t y o r f i t n e s s , h o w e v e r , r e m a i n s c o n t r o v e r s i a l i n b o w l i n g (Briggs; 1 9 9 8 a ; B r i g g s , 1998b). T h i s c r o s s - s e c t i o n a l s t u d y e x a m i n e s t h e c o n - e l a t i o n b e t w e e n v a r i o u s p h y s i o l o g i c a l p a r a m e t e r s a n d b o w l i n g p e r f o r m a n c e i n a g r o u p o f 4 2 e l i t e b o w l e r s i n S i n g a p o r e , w i t h t h e a i m o f i d e n t i f y i n g u s e f u l p e r f o r m a n c e i n d i c a t o r s . T h e i n d e p e n d e n t v a r i a b l e s s t u d i e d i n c l u d e d b o t h a n t h r o p o m e t r i c a n d p h y s i o l o g i c a l p a r a m e t e r s . Age w a s r e c o r d e d t o d e t e r m i n e i t s r e l a t i o n s h i p to p e r f o r m a n c e i n b o w l i n g . H e i g h t a n d w e i g h t w e r e m e a s u r e d to d e t e r m i n e if a c e r t a i n p h y s i q u e w a s a d v a n t a g e o u s

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in the sport. As t h e s p o r t involves r e p e a t e d r n n - u p s to t h e lane, r e p e a t e d swinging of a 11-16 p o u n d ball, r e p e a t e d p u s h i n g - o f f a n d lunging b y t h e lower limbs, a n d t r u n k a n d hip flexion, t h e following physiological p a r a m e t e r s w e r e m e a s u r e d : aerobic c a p a c i t y (as reflected b y t h e aerobic p o w e r index), bowling grip s t r e n g t h (using a three-finger grip), lower b o d y s t r e n g t h [as reflected b y t h e 10-RM leg p r e s s p e r f o r m a n c e ) , a n d flexibility (as reflected b y t h e s i t - m i d - r e a c h distance) respectively. In addition, t h e s t u d y also c o m p a r e d lhe physiological profiles o f bowlers classified a s h e a v y ball s t r o k e r s , h e a v y ball c r a n k e r s , a n d light ball s p i n n e r s to d e t e r m i n e if e a c h of t h e s e t h r e e r e l e a s e s were a s s o c i a t e d w i t h a p a r t i c u l a r p h y s i q u e or p h y s i c a l ability.

If t h e r e l a t i o n s h i p b e t w e e n v a r i o u s physiological p a r a m e t e r s a n d bowling p e r f o r m a n c e c a n b e d e t e r m i n e d , t h e n bowlers c a n a p p o r t i o n t h e a p p r o p r i a t e a m o u n t of t i m e to p h y s i c a l training. To t h e a u t h o r s ' knowledge, t h i s is t h e In-st t i m e t h a t s u c h a s t u d y h a s b e e n c o n d u c t e d in t h e p a s t 20 y e a r s .

Methods and Procedures SubjeCtS Forty-two b o w l e r s f r o m t h e 1998 S i n g a p o r e National T e n - P i n Bowling T r a i n i n g S q u a d v o l u n t e e r e d for t h i s study. Of t h e 42 bowlers, t h e r e were 26 m a l e s ( m e a n age 34_+10 yrs, m e a n height 172.1_+6.9 cm, m e a n weight 68.8_+14.1 kg) m i d 16 f e m a l e s ( m e a n age 28_+8 yrs, m e a n height 159.8 _+ 3.9 cm, m e a n weight 54.2_+6.6 kg). T h e 42 s u b j e c t s c o m p r i s e d 34 a d u l t (senior) a n d eight y o u t h bowlers. T h e 34 a d u l t bowlers w e r e selected b a s e d o n t h e i r r a n k i n g s a t the e n d of t h e p r e v i o u s y e a r (the top 3 6 bowlers w e r e selected to j o i n t h e t r a i n i n g s q u a d , b u t two declined). T h e eight y o u t h bowlers t h a t w e r e c o - o p t e d to join t h e training s q u a d c o m p r i s e d t h e top four m a l e y o u t h bowlers ( m e a n age 18_+3 yrs, m e a n h e i g h t 177.5_+2.0 cm, m e a n weight 70.0_+12.4 kg) a n d the top four female y o u t h b o w l e r s ( m e a n age 19_+3 yrs, m e a n h e i g h t 160.5+_5.3 cm, m e a n weight 53.2_+6.0 kg) in t h e country. Hence, t h e s u b j e c t s w e r e elite competitive bowlers, two of w h o m w e r e a t t h e top of t h e m e n ' s a n d w o m e n ' s Asian Bowling T o u r R a n k i n g d u r i n g t h e y e a r of t h e s t u d y .

Measurements I n addition to t h e age (years), height (cm_+0.5), a n d weight (kg_+0.1), (Seca, Model 708, H a m b u r g , G e r m a n y ) , t h e type of bowling r e l e a s e u s e d b y e a c h bowler w a s also noted. T h i s w a s o b t a i n e d b y interviewing t h e n a t i o n a l coach, w h o classified h i s bowlers a s h e a v y ball s t r o k e r s (a release r e s u l t i n g in the ball rolling e n d - o v e r - end) , h e a v y ball c r a n k e r s (characterised b y a lbrceful swing a n d release), mid light ball s p i n n e r s (a r e l e a s e c a u s i n g the ball to r o t a t e like a Kvro). After t h e a n t h r o p o m e t r i c m e a s u r e m e n t s w e r e m a d e , bowling grip s t r e n g t h w a s m e a s u r e d , followed b y t h e aerobic p o w e r index, lower b o d y s t r e n g t h , a n d Finally s i t - a n d - r e a c h distance. The interval b e t w e e n t h e m e a s u r e m e n i of t h e aerobic p o w e r i n d e x (which is a s u b m a x i m a l test) a n d t h e lower body s t r e n g t h w a s a t least 30 m i n u t e s . All t h e a b o v e d a t a were collected d u r i n g a single, h a l f - d a y session. Prior to t h e testing, t h e bowlers were informed, t h r o u g h t h e i r coach, t h a t t h e y s h o u l d a d h e r e to their u s u a l diets. None of t h e bowlers h a d u n d e r g o n e rely physical t r a i n i n g p r o g r a m to s u p p l e m e n t t h e i r bowling practice s e s s i o n s for a period of t h r e e m o n t h s prior to t h e testing. A e r o b i c p o w e r i n d e x T h e m e a s u r e of aerobic c a p a c i t y w a s c o n d u c t e d on a Lode cycling ergometer,

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Figure 1: The bowling grip Strength test.

m o d e l Corival 4 0 0 (Groningen. Holland). T h e aerobic p o w e r index (W~.kg-1) is t h e relative p o w e r a t t a i n e d w h e n cycling a t 75% of t h e individual's e s t i m a t e d m a x i m u m h e a r t rate. i.e. 0.75 x (220-age). T h e s u b m a x i m a l t e s t protocol w a s b a s e d o n Telford et al. (1989).

Bowling grip strength Unlike t h e c o n v e n t i o n a l five-finger grip s t r e n g t h t e s t (Balogun et al., 1991), t h e bowling grip s t r e n g t h t e s t w a s p e r f o r m e d o n the bowling h a n d u s i n g only t h e t h u m b , middle, a n d ring fingers, s i m i l a r to t h e w a y a bowling ball is h e l d (Fig. 1). T h e index finger w a s k e p t e x t e n d e d while t h e little finger w a s either e x t e n d e d or flexed d e p e n d i n g o n w h a t t h e bowler w a s a c c u s t o m e d to w h e n bowling. T h e s u b j e c t s stood w i t h t h e elbow straight, h a n d held c o m f o r t a b l y a l o n g t h e side of t h e body, a n d t h e wrist in m i d - p r o n a t i o n . T h e s u b j e c t s w e r e i n s t r u c t e d to tighten their grip g r a d u a l l y r a t h e r t h a n to u s e a s u d d e n jerk. E a c h s u b j e c t w a s given t h r e e trials, with a m i n i m u m r e s t interval of 25 s e c o n d s b e t w e e n trials. T h e h i g h e s t m e a s u r e m e n t w a s t a k e n a s t h e bowling grip s t r e n g t h . All m e a s u r e m e n t s were m a d e in Newtons to o n e d e c i m a l place, u s i n g a grip s t r e n g t h d y n a m o m e t e r (Takei, m o d e l T.K.K. 5101, Tokyo, J a p a n ) , with t h e grip r a n g e a d j u s t e d s u c h t h a t prior to gripping, t h e p r o x i m a l i n t e r p h a l a n g e a l j o i n t of t h e middle finger w a s flexed to 90 degrees. Verbal e n c o u r a g e m e n t w a s c o n s i s t e n t l y given for e a c h trial.

IO-RM leg press performance As a m e a s u r e of lower b o d y s t r e n g t h , t h e 10 repetition m a x i m u m (10-RM) concentric leg p r e s s s t r e n g t h (kg+0.1) w a s d e t e r m i n e d o n a s u p i n e leg p r e s s m a c h i n e (Cybex Eagle F i t n e s s S y s t e m s , m o d e l 4 1 0 0 with s t a n d a r d weight s t a c k ,

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NY, USA). After five m i n u t e s of stretching the lower limb m u s c u l a t u r e a n d w a r m i n g u p (with one s u b m a x i m a l set of 10 leg presses u s i n g a 22.5 kg load), each subject positioned h i m s e l f / h e r s e l f on the m a c h i n e with the feet a p a r t at shoulder-width, toes slightly pointing out, a n d the knees a n d hips extended. For e a c h of the 10 repetitions, the subject lowered h i s / h e r torso to the level where the thighs were p e r p e n d i c u l a r to the torso before p u s h i n g h i s / h e r torso u p w a r d s until the knees were once again fully extended. An increment of 4.5 kg (i.e., one plate) was u s e d between the 10-RM sets, with a n interval of at least one m i n u t e between sets, until the 10-RM was established. Due to administrative constraints, only h a l f the subjects (n = 21) were r a n d o m l y selected a n d tested lbr the 10-RM lower b o d y strength. Of those selected, four were u n a b l e to undergo testing b e c a u s e of injuries u n r e l a t e d to the testing. These bowlers were not substituted.

S i t - a n d - r e a c h d i s t a n c e The s i t - a n d - r e a c h forward test (Schmidt, 1996) w a s used as a m e a s u r e of the bowler's lower b a c k a n d h a m s t r i n g flexibility. After stretching the b a c k a n d h a m s t r i n g s for six minutes, the subjects sat on a s t a n d a r d s i t - a n d - r e a c h forward b o a r d which kept the ankles at right-angles, a n d the knees extended. A tape w a s placed on the board, between the legs, with the 5 0 - c m m a r k at the b o t t o m of the heels. The subjects t h e n r e a c h e d forward with the o u t s t r e t c h e d h a n d s , sliding the fingertips along the tape a s far forward as possible a n d holding the position for at least two seconds. The best of three non=ballistic a t t e m p t s w a s recorded in centimetres to the n e a r e s t 0.5 cm.

Bowling performance The scores from a selection trial were used as a m e a s u r e of the bowling performance. All 42 m e m b e r s of the training s q u a d participated in the trials to compete for 10 m e n ' s a n d 5 w o m e n ' s slots in the 1998 National Squad. Incentives for m a k i n g it into the s q u a d included s p o n s o r s h i p for local a n d overseas events, a n d a c h a n c e to compete in the 1998 C o m m o n w e a l t h Games a n d Asian Games. The trials were held within a m o n t h after the physiological tests were completed, a n d there w a s no physical training d u r i n g the interim period. During the selection trials, e a c h bowler participated in six roll-offs (six g a m e s per roll-off) held at six different venues, with one roll-off per day for two consecutive days, followed b y a rest day before the next cycle of two days of roil-offs a n d one rest d a y commenced. Hence three cycles were completed per bowler. The worst roll-off result w a s discarded, a n d the average points per game from the best five roH-offs was u s e d a s a m e a s u r e of their performance.

Statistical method The Statistical Package for Social Sciences (SPSS 8.0 for Windows} was u s e d for the statistical analyses. Two-tailed independent t-tests were u s e d to c o m p a r e bowling scores a n d physiological m e a s u r e m e n t s between male adults a n d male y o u t h s , between female a d u l t s a n d female y o u t h s , between males a n d females, a n d between female heavy ball strokers a n d female light ball spinners. O n e - w a y analysis of variance (ANOVA) was c o n d u c t e d to c o m p a r e bowling scores a n d physiological m e a s u r e m e n t s between male heavy ball strokers, heavy ball crankers, a n d light ball spinners. For the male a n d female bowlers, s e p a r a t e bivariate a n a l y s e s were c o n d u c t e d to determine the Pearson p r o d u c t m o m e n t correlation coefficients between the bowling score a n d each of the physiological m e a s u r e m e n t s . Bivariate r a t h e r t h a n mutlivariate analysis was u s e d b e c a u s e the

i 7 9

sex N Minimum Maximum Mean Std Deviation

Age (yrs)

Heigbt(cm)

Weight (kg)

Aerobic power index (W kg "1)

Bowling grip strength (N)

IO-RM leg press (kg)

Sit-and-Reach (cm)

Average bowling score from trials (points per game)

Males 26 16 48 34 10 Females 16 16 44 28 8 All 42 16 48 32 10 Males 26 159.0 181.0 172.1" 6.9 Females 16 155.0 168:0 159.8 3.9 All 42 15510 181.0 167.4 8.4 Males 26 51.8 116.8 68.8* 14.1 Females 16 44.5 64.4 54.2 6.6 All 42 44.5 116.8 63.2 13.7 Males 26 1.40 3.32 2.26* 0.51 Females 15 1.37 2.74 1.96 0.37 All 41 1.37 3.32 2.15 0.48 Males 26 175.5 359.9 271.6" 49.0 Females 13 139.3 211.8 175.5 21.6 All 39 139.3 359.9 240.3 61.8 Males 13 36.4 73.4 59.2 10.2 Females 4 31.8 54.4 46.6 10.7 All 17 31.8 73.4 56.2 1i.4 Males 24 26.5 61.0 46.5 8.4 Females 15 25.0 64.0 50.4 11.6 All 39 25.0 64.0 48.0 9.8 Males 26 t60.57 211.53 196.25" 9.82 Females 16 176.20 211.70 188.63 9.23 Al~ 42 160.57 211.70 193.34 10.21

* Males significantly higher than females (p<O.05)

Table 1: Descriptive statistics for male bowlers, female bowlers and all bowlers.

m a i n p u r p o s e of this s t u d y w a s to identify p e r f o r m a n c e indicators r a t h e r t h a n to e s t a b l i s h a c a u s a l link~ T h e significance level w a s s e t a t ct= 0.05.

ReSults T h e f o u r m a l e a n d f o u r f e m a l e y o u t h bowlers h a d bowling s c o r e s t h a t w e r e n o t significantly different f r o m t h e i r a d u l t counterparts~ Hence, t h e i r d a t a were n o t s e g r e g a t e d f r o m t h e a d u l t s ' w h e n Conducting t h e s u b s e q u e n t a n a l y s e s .

T h e descriptive s t a t i s t i c s for t h e m a l e a n d female bowlers a r e s h o w n in T a b l e 1. Although all t h e s u b j e c t s p a r t i c i p a t e d in t h e trials, n o t all c o m p l e t e d t h e i r t e s t s d u e to v a r i o u s injuries. T h e m e n w e r e significantly taller a n d h e a v i e r t h a n t h e w o m e n . T h e y also h a d significantly h i g h e r aerobic p o w e r indices, bowling grip s t r e n g t h , a n d bowling s c o r e s c o m p a r e d to t h e females.

O f t h e 2 6 m a l e bowlers in t h e t r a i n i n g s q u a d , t h e r e w e r e 11 s t r o k e r s (42%), 4 c r a n k e r s (15%), a n d 11 s p i n n e r s (42%). A m o n g s t t h e 16 female bowlers, t h e r e were l 1 s t r o k e r s (69%), 5 s p i n n e r s (31%), a n d n o c r a n k e r s . Within t h e g r o u p o f m a l e bowlers a n d t h e g r o u p o f female bowlers, t h e r e w a s n o significant difference in bowling s c o r e s o r physiological m e a s u r e m e n t s w h e n all t h r e e r e l e a s e s w e r e c o m p a r e d .

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Age Height Weight A e r o b i c B o w l i n g IO-RM Sit-and (yrs) (cm) (kg) power grip leg Reach

index strength press (cm) (w,kg "1) (N) (kg)

Male Pearson correlation 0.30 -0.14 -0.22 0.13 0.07 -0.18 0.22 (vs. bowling score)

Significance (p) 0.14 0.49 0.29 0.54 0.72 0.56 0.30 N 26 26 26 26 26 13 24

Female Pearson correlation 0.31 °0.05 -0.28 0.63* -0.12 -0.60 -0.08 (vs. bowling score)

Significance (p) 0.25 0.84 030 0.01 0.70 0.41 0.79 N 16 16 16 15 13 4 15

* Correlation is significant at the 0.05 level (2-tailed)

Table 2: Pearson correlation coe~dents ~r) between average bowling score and physiological parameters in male and female bowlers.

E iii t o 200 J

o o o o ° ° o u ~

o

19o J

180 J 0 o

170

J2 1-4 1.'6 1"6 ~ 0 2"2 2:4 2?6

Aerobic Power Index (W.kg 1)

r = 0.63 (p < 0.05) Rsq = 0,3939

F~jure 2: Scatter plot of bowling score vs aerobic power index for female bowlers.

For the male bowlers, bivariate analysis showed t h a t n o n e of the a n t h r o - pometric m e a s u r e m e n t s (age, height, weight) or physiological m e a s u r e m e n t s (aerobic power index, bowling grip strength, 10-RM leg press performance, a n d s i t - a n d - r e a c h distance) showed a n y correlation with the bowling scores (Table 2). For the women, aerobic power index was the only p a r a m e t e r t h a t showed a significant correlation to the bowling score (Table 2 a n d Fig. 2). The correlation coefficient between aerobic power index a n d average bowling score for the female bowlers w a s 0.63; the 95% confidence interval w a s 0.17 to 0.86. F r o m Figure 2, a possible outlier (aerobic power index = 2.74, average bowling score = 211.7) is apparent. However, o n analysis u s i n g a box plot, the d a t a value w a s within the u p p e r a n d lower quartile range. Hence, the d a t a point w a s n o t considered a n outlier b y definition. F u r t h e r m o r e , this female m e m b e r of the s t u d y satisfied all other criteria for inclusion in the study.

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Discussion F o r m o s t s p o r t s , t h e r e a r e generally t h r e e a r e a s a n a t h l e t e h a s to c o n c e n t r a t e o n in o r d e r to i m p r o v e h i s / h e r p e r f o r m a n c e : technical skill development, p s y c h o - logical capacity, a n d physiological c a p a c i t y (Winter, 1995). I n t h e s p o r t of t e n - p i n bowling, few w o u l d d i s p u t e t h a t t e c h n i c a l a n d psychological skills (Newton & D u d a , 1993; T h o m a s et al., 1996) play a m a j o r role in achieving h i g h scores. T h e e x t e n t to w h i c h physiological c a p a c i t y or fitness c o n t r i b u t e s to p e r f o r m a n c e , however, r e m a i n s controversial in bowling (Briggs, 1998a; Briggs, 1998b). It is i m p o r t a n t to elucidate t h e r e l a t i o n s h i p b e t w e e n v a r i o u s physiological p a r a m e t e r s a n d bowling s u c c e s s so t h a t b o w l e r s c a n a p p o r t i o n t h e a p p r o p r i a t e a m o u n t of t i m e to p h y s i c a l conditioning. In t h i s c r o s s - s e c t i o n a l study, selected p a r a m e t e r s (age, height, weight, a e r o b i c p o w e r index, bowling grip s t r e n g t h , 10-RM leg p r e s s p e r f o r m a n c e , a n d s i t - a n d - r e a c h distance) w e r e m e a s u r e d to see if t h e y h a d a n y correlation with bowling p e r f o r m a n c e . S c o r e s f r o m t h e selection trials for National r e p r e s e n t a t i o n were u s e d a s a criterion m e a s u r e of bowling p e r f o r m a n c e , w i t h t h i s e v e n t h e l d within o n e m o n t h a f t e r t h e physiological t e s t i n g period.

F o r b o t h t h e m a l e a n d female bowlers, t h e r e w a s a v e r y wide s p r e a d in t e r m s of age, height, a n d weight. F o r example, t h e r e w a s a difference of 32 y r s b e t w e e n t h e oldest a n d y o u n g e s t male; 22 c m b e t w e e n t h e tallest a n d s h o r t e s t m a l e ; a n d 6 5 k g b e t w e e n t h e h e a v i e s t a n d lightest male. Nevertheless, age, height, a n d weight did n o t correlate significantly with t h e a v e r a g e bowling s c o r e s for e i t h e r t h e m a l e s or t h e females. T h i s s u p p o r t s t h e belief t h a t bowlers of widely d i f f e n n g a g e s a n d p h y s i c a l a t t r i b u t e s c a n b e equally competitive in t h e sport.

T h e aerobic p o w e r index gives a n e s t i m a t e of t h e a t h l e t e ' s a e r o b i c capacity. A l t h o u g h it is n o t a s a c c u r a t e a s a direct m e a s u r e m e n t of t h e m a x i m a l oxygen u p t a k e (VO2max}, Minikin a n d Telford {1991) s h o w e d t h a t t h e aerobic p o w e r i n d e x w a s able to d i s t i n g u i s h b e t w e e n m a l e 100 m a n d 4 0 0 m freestyle s w i m m e r s . Telford et al. (1989) r e p o r t e d a high t e s t - r e t e s t reliability of 0.97 for t h e aerobic p o w e r index. Being a s u b m a x i m a l iest, t h e aerobic p o w e r i n d e x is e a s i e r to m e a s u r e , s a f e r for b o w l e r s (who typically do n o t h a v e a v e r y high p h y s i c a l t r a i n i n g s t a t u s c o m p a r e d with "most athletes), a n d is p r o b a b l y also m o r e specific for bowling (whose a e r o b i c d e m a n d is n o t maximal) c o m p a r e d to a VO2max test. A l t h o u g h t h e aerobic d e m a n d for e a c h g a m e (the bail is s w u n g 12-21 t i m e s p e r game) is n o t high, s o m e m a y a r g u e t h a t t o w a r d s t h e e n d of t h e d a y (up to 22 g a m e s c a n b e p l a y e d in o n e day) a bowler w h o is aerobically unfit m a y s t a r t to fatigue a n d lose h i s / h e r c o n c e n t r a t i o n (Briggs, 1998b). Indeed, o u r r e s u l t s s h o w t h a t female b o w l e r s with h i g h e r aerobic p o w e r indices t e n d e d to h a v e h i g h e r s c o r e s d u r i n g t h e trials (r = 0.63, p<0.05). T h o u g h significant, t h e correlation w a s a t m o s t only m o d e r a t e , so it n e e d s to b e t r e a t e d with c a u t i o n a n d f u r t h e r s t u d i e s will b e n e c e s s a r y to c o n f i r m this. For t h e m e n , t h e r e w a s no correlation b e t w e e n t h e aerobic p o w e r index a n d t h e a v e r a g e bowling score. Since t h e m e n h a d significantly h i g h e r aerobic indices t h a n t h e w o m e n ( m e a n aerobic p o w e r index of 2.26 vs. 1.96 W . k g l } , it m a y b e possible t h a t t h e r e is a t h r e s h o l d aerobic c a p a c i t y required for competitive bowling, b e y o n d w h i c h a n y f u ~ h e r i n c r e a s e s will h a v e a limited effect o n p e r f o r m a n c e . However, t h i s r e m a i n s to b e investigated; D u r i n g the selection trials, only six g a m e s were p l a y e d p e r day. A typical t o u r n a m e n t involves 6 - 1 8 g a m e s p e r d a y a n d is, o n t h e whole, m o r e taxing t h a n t h e trials. P e r h a p s if p o i n t s f r o m t h e finals of a t o u r n a m e n t (this u s u a l l y c o m p r i s e s m o r e t h a n six games) i n s t e a d of t h e selection trials w e r e u s e d a s a p e r f o r m a n c e

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m e a s u r e , a significant correlation could t h e n b e d e m o n s t r a t e d even for t h e males. As t h e correlation b e t w e e n the aerobic power index a n d p e r f o r m a n c e w a s only m o d e r a t e in t h e w o m e n a n d non-significant in the m e n , f u r t h e r i n v e s t i g a t i o n s n e e d to b e d o n e before aerobic e n d u r a n c e training c a n b e confidently r e c o m - m e n d e d to bowlers a s a n effective m e a n s of e n h a n c i n g p e r f o r m a n c e .

E a c h bowler r e p e a t e d l y swings a 11-16 p o u n d ball b e t w e e n 72 to 126 t i m e s p e r d a y d u r i n g t h e qualifying r o u n d s of a t o u r n a m e n t (12-21 swings p e r g a m e , six g a m e s p e r day). As t h i s is fatiguing (Martin et al., 1990), a s t r o n g grip is a s s u m e d to b e n e c e s s a r y for c o n s i s t e n c y t o w a r d s t h e e n d of the day. W h e n m e a s u r i n g grip s t r e n g t h for bowlers, t h e conventional five-finger grip m a y not b e a p p r o p r i a t e . Waldo (1996) c o m m e n t e d t h a t t h e conventional five-finger grip s t r e n g t h d o e s n o t p r e d i c t p e r f o r m a n c e in athletics, a n d this is likely to b e t h e c a s e for bowling a s well, since t h e bowling ball is held u s i n g only t h r e e fingers. To f o r m u l a t e a m o r e specific a n d hopefully m o r e valid t e s t for bowlers, tile conventional grip s t r e n g t h t e s t w a s modified s u c h t h a t only t h e fingers u s e d in holding t h e bowling ball w e r e tested. In t h i s modified t e s t - t h e bowling grip s t r e n g t h t e s t - only t h e t h u m b , middle, a n d ring fingers w e r e u s e d to hold the' d y n a m o m e t e r . A s e p a r a t e investigation (Tan et al., in print) c o n d u c t e d o n 21 bowlers (12 m e n a n d 9 women) f r o m t h e s a m p l e of s u b j e c t s u s e d in t h i s s t u d y showed t h a t the bowling grip s t r e n g t h t e s t h a d a t e s t - r e t e s t reliability of 0.91 (p<0.01). Despite t h e h i g h reliability a n d logical validity, t h e correlation b e t w e e n t h e bowling grip s t r e n g t h a n d bowling score w a s n o t significant in this g r o u p of elite bowlers. A s t r o n g grip m a y e n a b l e a bowler to e x e c u t e a m o r e effective t e c h n i q u e a n d it m a y allow t h e bowler to m a i n t a i n h i s / h e r f o r m t h r o u g h o u t t h e event. On the o t h e r h a n d , it m a y b e a r g u e d t h a t a ' p r o p e r ' technique, r a t h e r t h m l a high grip s t r e n g t h , is needed. Hence, t h e failure to d e m o n s t r a t e a significant correlation could m e a n t h a t t h e s u b j e c t s h a d good technique, or t h a t tile s i x - g a m e s - p e r - d a y played d u r i n g t h e trials w a s n o t rigorous e n o u g h to t a x the bowlers' grip strength, or t h a t t h e s u b j e c t s h a d exceeded t h e t h r e s h o l d grip s t r e n g t h needed to bowl competitively.

Lower b o d y s t r e n g t h w a s m e a s u r e d u s i n g t h e 10 repetition m a x i n m m (10-RM) concentric leg p r e s s . T h e r e a s o n the 10-RM w a s c h o s e n over the u s u a l 1-RM for s t r e n g t h m e a s u r e m e n t w a s t h a t it is c o n s i d e r e d a safer alternative (Abernethy et al., 1995), p a r t i c u l a r l y a s t h r e e bowlers s u s t a i n e d b a c k injuries d u r i n g t h e p r e v i o u s y e a r ' s 1-RM test. F u r t h e r m o r e , a c c o r d i n g to Braith et al. (1993), t h e 10- RM m e a s u r e m e n t c a n a c c u r a t e l y predict 1-RM strength. Lower b o d y s t r e n g t h , especially for t h e slide leg, is n e e d e d to decelerate the b o d y a s t h e b o w l e r t'slides" d u r i n g t h e l a s t 1.5 m of t h e a p p r o a c h a n d it m a y also b e m l i m p o r t a n t c o n t r i b u t i n g factor to a c o n s i s t e n t r e l e a s e in a long t o u r n a m e n t . It c a n b e a r g u e d t h a t lower b o d y s t r e n g t h is n o t n e c e s s a r y if the bowler h a s a good t i m i n g s e q u e n c e b e t w e e n t h e swing a n d t h e f o o t w o r k . Unfortunately, d u e to a d m i n i s t r a t i v e r e a s o n s , it w a s n e c e s s a r y to limit t h e n u m b e r of s u b j e c t s for t h e 10-RM m e a s u r e - m e n t . T h e s m a l l n u m b e r of s u b j e c t s t h a t p e r f o r m e d t h e t e s t (13 m a l e s , 4 females) p r o b a b l y c o n t r i b u t e d to the failure to s h o w a n y correlation b e t w e e n lower b o d y s t r e n g t h a n d p e r f o r m a n c e . F u r t h e r m o r e , a l t h o u g h a mtnimun~ r e s t interval of o n e m i n u t e h a s b e e n s h o w n to b e sufficient in d e t e r m i n i n g 1-RM s t r e n g t h (Weir et al., 1994), it m a y n o t h a v e provided a d e q u a t e r e c o v e r y b e t w e e n t h e 10-RM m e a s u r e m e n t s in o u r u n t r a i n e d subjects. H e n c e , n o firm c o n c l u s i o n s c a n b e m a d e r e g a r d i n g t h e correlation b e t w e e n lower b o d y s t r e n g t h a n d p e r f o r m a n c e f r o m t h i s study.

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i n m o s t sports, s t r e t c h i n g is routinely p e r f o r m e d . For bowling, however, it is n o t a c o m m o n p r a c t i c e e s p e c i a l l y a m o n g t h e a d u l t b o w l e r s (Woo, p e r s o n a l c o m m u n i c a t i o n ) . Flexibility w a s m e a s u r e d u s i n g the s i t - a n d - r e a c h test, w h i c h r e q u i r e s flexible h a m s t r i n g s , o t h e r hip extensors, a n d p a r a v e r t e b r a l m u s c l e s for good s c o r e s in t h e test. T h r o u g h o u t t h e bowling a p p r o a c h , t h e s e m u s c l e g r o u p s a r e h a r d l y s t r e t c h e d , so it is n o t s u r p r i s i n g t h a t t h e s i t - a n d - r e a c h m e a s u r e m e n t s did n o t c o r r e l a t e with t h e p e r f o r m a n c e . While s t r e t c h i n g m a y p r e v e n t injury, its u s e f u l n e s s in bowling p e r f o r m a n c e is doubtful.

B a s e d on t h e i r releases, bowlers c a n b e classified a s h e a v y ball s t r o k e r s , h e a v y ball c r a n k e r s , a n d light ball s p i n n e r s (Woo, p e r s o n a l c o m m u n i c a t i o n ) . C r a n k e r s u s e a m o r e forceful swing a n d release, a n d t e n d to b e s u c c e s s f u l on l a n e s d e m a n d i n g less a c c u r a c y in hitting t h e "pocket." S t r o k e r s , o n t h e o t h e r h a n d , roll t h e ball e n d - o v e r - e n d a n d t e n d to s c o r e on a c c u r a c y - d e m a n d i n g lanes. S p i n n e r s utilise a t e c h n i q u e w h e r e t h e ball r o t a t e s m u c h like a gyro a n d s e e m to b e less a f f e c t e d b y l a n e c o n d i t i o n s t h a n h e a v y b o w l e r s (Bergendorff, p e r s o n a l communication). In o u r g r o u p of subjects, all t h r e e t y p e s of r e l e a s e s p r o d u c e d s c o r e s t h a t w e r e n o t significantly different f r o m o n e another, b u t t h i s is n o t s u r p r i s i n g a s e a c h bowler w a s e x p o s e d to different v e n u e s a n d l a n e conditions d u r i n g t h e trials.

T h e p h y s i c a l d e m a n d is a n e c d o t a l l y t h o u g h t to b e r e l a t e d to t h e type of release: c r a n k e r s a r e t h o u g h t to b e s t o u t a n d s t r o n g , w h e r e a s size a n d s t r e n g t h a r e t h o u g h t to b e l e s s r e l e v a n t to s t r o k e r s a n d light b a l l s p i n n e r s (Bergendorff, p e r s o n a l eommunication}. D e s p i t e t h e s e o b s e r v a t i o n s , all physiological p a r a - m e t e r s including height, weight, a n d s t r e n g t h m e a s u r e s w e r e s i m i l a r b e t w e e n all t h r e e g r o u p s .

A l t h o u g h t h e s t r e n g t h a n d flexibility m e a s u r e m e n t s in t h i s s t u d y did n o t correlate w i t h t h e a v e r a g e bowling score, it d o e s n o t m e a n t h a t b o w l e r s c a n c o m p l e t e l y ignore grip s t r e n g t h , lower b o d y s t r e n g t h , a n d flexibility training. S t r e n g t h a n d flexibility m a y n o t correlate with p e r f o r m a n c e in elite bowlers, b u t t h e y m a y still b e a d v a n t a g e o u s to t h e bowler since t h e y c a n d e c r e a s e t h e r i s k o f o v e r u s e injuries (Duda, 1988).

Conclusion Bowlers of relatively d i v e r s e a g e a n d build c a n b e equally competitive in t h e s p o r t of t e n - p i n bowling. T h e r e w a s a positive correlation b e t w e e n t h e aerobic powe r i n d e x a n d t h e a v e r a g e bowling s c o r e s in t h e female bowlers w h o p a r t i c i p a t e d in this s t u d y , indicating t h a t aerobic fitness m a y c o n t r i b u t e to bowling s u c c e s s . F u r t h e r investigations would b e n e c e s s a r y to c o n f i r m this. As t h e r e w a s n o s u c h correlation for t h e m e n who, o n average, h a d a h i g h e r aerobic index, it is p r o p o s e d t h a t t h e r e m a y exist a t h r e s h o l d level of aerobic fitness required for s u c c e s s in t h e s p o r t , b e y o n d w h i c h f u r t h e r i n c r e a s e s in aerobic c a p a c i t y will h a v e a negligible c o n t r i b u t i o n t o w a r d s i m p r o v i n g p e r f o r m a n c e . This r e m a i n s to b e investigated.

Although grip s t r e n g t h a n d lower b o d y s t r e n g t h a r e p r e s u m e d to b e i m p o r t a n t d u e to t h e n a t u r e of t h e sport, this s t u d y failed to d e m o n s t r a t e a n y correlation b e t w e e n t h o s e two s t r e n g t h m e a s u r e s a n d p e r f o r m a n c e . T h e c o n c l u s i o n b e t w e e n lower b o d y s t r e n g t h a n d p e r f o r m a n c e , however, is n o t a Firm one d u e to the s m a l l s a m p l e size u s e d in this s t u d y . While flexibility m a y r e d u c e i n j u r y rates, it did n o t correlate with p e r f o r m a n c e .

H e a v y ball s t r o k e r s , h e a v y ball c r a n k e r s , aald light ball s p i n n e r s h a v e distinctly

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different bowlhlg styles, b u t in o u r g ro u p of bowlers, n o n e d e m o n s t r a t e d a n y superiority over the o t h e r s in t e r m s of bowling p eri b rm an ce. Th e m~thropometric a n d physiological m e a s u r e s were also similar between the t h r e e groups.

On the whole, it seems t h a t th e c o m m o n anthropometliC amd physiological m e a s u r e m e n t s do not a d e q u a t e l y predict p e r f o r m a n c e in the sp o rt of t e n - p i n bowling at t h e elite level. This is p ro b ab l y b e c a u s e o t h e r factors like m e n t a l skills a n d t e c h n i q u e have a g r e a t e r c o n t r i b u t i o n to bowling s u c c e s s at t h a t level.

Acknowledgements The a u t h o r s would like to t h a n k J e n n i f e r Tan, l ~e Hong Choo, a n d J o s e p h Ch i an g for their a s s i s t a n c e as well as G o r a n Bergendorff, Mike Boroskae, aald Willimn Woo of the Singapore T e n p i n Bowling Congress for their input.

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