biomechanical and strength predictors of fast bowling

8/11/2019 Biomechanical and Strength Predictors of Fast Bowling

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Table 1. ACB report on player matches available from 1996 to 2002

Team 1996 1997 1998 1999 2000 2001 2002

Australia 414 1218 1020 1327 1108 1153 748

New South Wales 416 464 468 510 504 566 664

Queensland 357 396 396 350 399 494 566

South Australia 306 330 459 465 387 413 530Tasmania 255 270 306 303 308 475 566

Victoria 405 432 416 455 363 523 556

Western Australia 342 396 414 367 449 570 587

Total 2495 3506 3479 3777 3518 4194 4217

Report taken from the ACB (Australian Cricket Board) Injury Report 2001-02

Table 2. Sport Health Report on designated player hours of exposure in matches each season

Competition 1999 2000 2001 2002 2003 2004 2005 2006

Domestic

One-day 1819 1732 2685 2685 2685 2685 2598 2598First Class

Domestic 8658 9048 8892 8892 8580 9438 9126 8892

One Day

International 996 1472 953 909 1386 1386 1039 1559

Test Cricket 2067 2067 1287 2379 1248 2691 2262 3042

Total 15539 16319 15818 16867 15902 18204 17030 18097

Report taken from Sports Medicine Australia(SMA)

Despite the increased playing hours the injury rates have remained relatively stable,

summarised in Table 3, with Figure 1 and Figure 2 showing the match load vs. injury rates.

Table 3. ACB and Sports Medicine Australia report on injuries/10000 player hours

Report 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006ACB 18.4 14.4 20.8 26.2 23.6 21.4 24.2SMA 37.7 34.9 29.7 37.7 31.7 37 27.3 25.1


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Figure 3. Top bowling speeds to date in international cricket (Cric Info:ESPN Cricket)

A greater knee angle at front foot contact (FFC) is a variable which is believed to be

moderate to strongly correlated to the release speed of the ball according to studies shown in

Table 4.

Table 4. Correlation between knee angle and ball release speed at front foot contact

Author r value P value

Wormgoor et al. (2008) r = +0.52 P = 0.005

Burden & Bartlett. (1990) r = +0.41

Loram et al. (2005) r = +0.71 P = 0.011

According to Bartlett et al.(2006) there are three types of knee actions:

1.

Straight leg (knee angle >150)

2. Flexed knee (knee angle 150

There are a number of reasons why a greater knee angle at FFC is thought to increase the

release speed of the ball. Elliot, Foster and Gray (1986) state that a greater knee angle

increases the tangential velocity of the ball, as it is released, due to a greater lever arm from

the front foot to the arm as the radial distance is increased. According to Portus et al. (2004) a

more stable platform is provided when the leg is straighter which causes the leg to be stiffer

allowing a more effective transfer of kinetic energy from the momentum of the run up. Thus

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BowlingSpeed(Km/h)

Time (Year)

Top Bowling Speed (km/h) Recorded Over Time

Bowling Speed (KPH)


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it is essential for the knee musculature to resist flexion upon FFC which is dependent upon its

eccentric ability whereas extension of the knee is a function of its concentric capacity

(Wormgoor et al., 2010). A number of studies have investigated this relationship between

knee isokinetic/isoinertial knee strengths and release speeds in Table 5.

Table 5. Lower limb strength measurements and release speed of ball

Study Test Results Findings

Wormgoor et al.

(2010)

Isokinetic strength

test of knee

flexion/extension

No significant

correlation between

isokinetic kneestrength

Negative correlation

between knee flexion

and release speed,implied knee needs

to resist flexion

Pyne et al. (2006) Isoinertial strength

test (Counter

Movement Jump)

Moderate

significance between

senior and juniors

with large effect size

(1.4)

Release speed was

greater for greater

lower limb strength

tests

Loram et al. (2005) Knee

extension/flexion

peak torques

No significant

relationship

(extension r = -0.11,

flexion r = -0.08)

Positive correlation

between knee angle

and release speed

however no strengthpredictors

This relationship is poorly understood. No relationship has been investigated between the

knee strength and the type of knee action. Instead statistical analysis has been performed with

the knee action and release speed of the ball. By investigating this relationship will allow

bowling coaches and S&C coaches to understand the following relationships:

1. Whether knee flexion is a purely a function of technique, as a study by Ranson et al.

(2009) showed that knee action angles have not be known to change despite coaching

interventions over a period of 2 years. Hence is it possible that knee strength training

will have no change in increasing knee extension

2.

Understanding the moderate inverse correlation (r2=0.41) between knee extension

angle and trunk strength/stability according to Portus et al. (2000) as bowlers with a


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development in the concentric phase (Turner & Jefferys, 2010). Similarly with the three types

of bowling action; side on, front on and mixed, there is more transverse rotation of the upper

body including the pelvis during the side on action which utilises the stretch shortening cycle

for rapid force development (Whitely, 2010). Though no significant difference in release

speed of the bowling actions has been found (Stockill & Barlett, 1992) it may appear that

bowlers utilise different modes of force and power production. For instance in the front on

and mixed action very little utilisation of the stretch shortening cycle prevails and these

bowlers may have greater strength/power in the pectoralis major and latissimus dorsi

compared to side on action. Hence the same strength tests do not apply to all types of bowling

actions. Thus consideration to the strength test designs must be given for the types of bowling

actions as the tests may not be fit for all.

Thus based on the models presented, and the lack of understanding of these technique and

strength relationships, this study shall aim to test the below hypothesis in order to

characterise these strength technique relationships:

H11: Knee flexing on FFC technique has weaker eccentric control of the knee musculature, as

the knee is unable to resist knee flexion

H12: Knee flexing on FFC technique has strong trunk strengths in order to compensate for a

loss in release speed

H13: Knee flexing on FFC technique has weaker ground braking forces as a result of weak

eccentric control of the knee musculature

H21: Knee extending on FFC technique has stronger eccentric control of the knee

musculature, as the knee is able to resist knee flexion


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H22: Knee extending on FFC technique has weaker trunk strengths as bowlers utilise the

deceleration due to eccentric loading of the lower extremities to transfer force in the kinetic

chain more so than the trunk

H23: Knee extending on FFC technique has stronger ground braking forces as a result of

greater eccentric control of the knee musculature

H31: Knee flexing and then extending on FFC technique is has greater utilisation of the

stretch shortening cycle

H32: Knee flexing and then extending on FFC technique results has weaker trunk strengths as

bowlers utilise the stretch shortening cycle in the lower extremities to transfer force in the

kinetic chain more so than the trunk

H33: Knee flexing and then extending on FFC technique has stronger ground braking forces

as a result of greater force production due to the stretch shortening cycle

H41: Weaker trunk strength is accompanied by relatively independent movement of the

shoulder joint due to the loss of force transfer in the kinetic chain

H51: Front on action has greater strength in the pectoralis major musculature

H52: Front on action has greater strength in the latissimus dorsi musculature

H61: Mixed action has greater strength in the pectoralis major musculature

H62: Mixed action has greater strength in the latissimus dorsi musculature

H71: Side on action has greater ability to utilise the stretch shortening cycle in the upper body

In order to test these hypothesis statistical analysis using Pearson product moment correlation

coefficients, independent t-tests and ANOVA analysis will be used using two-tailed and


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biomechanical and strength predictors of fast bowling

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