Biomechanical and Strength Predictors of Fast Bowling

Sajeel Chaudhry

Biomechanical and strength predictors of ball release speed for varying bowling actions in cricket fast bowlers Fast bowling is biomechanically the most highly studied area in cricket due to the high injury rates, particularly back injuries (Foster et al., 1989, Elliot, 2000) coupled with the success fast bowlers have bowling in excess of 85mph (Bartlett, Stockill, Elliot & Burnett, 1996). As fast bowlers are considered critical components to the success of the teams, biomechanical research continues to explore the factors that contribute to the increase in the release speed of the ball. As a result recent studies have been conducted in trying to understand factors such as technique, anthropometric and strength correlations with the release speed of the ball (Pyne et al., 2006; Wormgoor, Harden & McKinon, 2010; Worthington, King & Ranson, 2013). These studies have yet to conclusively be able to determine contributing factors that most influence the release speed of the ball and much more research is required in understanding scientific evidence behind the performance aspect of bowling (Bartlett, 2003). Thus the aim of this study is to characterise the strength and ball release speed correlates between the various types of bowling actions, as analysts have looked into the joint kinematics and strength correlates with the release speed of the ball independently, however have failed to establish the relationship between these two areas. In the past decade the physical demands of fast bowling have increased steadily due to the increased match schedules at both domestic and international level which are summarised in Table 1 and Table 2.

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Sajeel Chaudhry

Table 1. ACB report on player matches available from 1996 to 2002 Team Australia New South Wales Queensland South Australia Tasmania Victoria Western Australia Total

1996 414 416 357 306 255 405 342 2495

1997 1218 464 396 330 270 432 396 3506

1998 1020 468 396 459 306 416 414 3479

1999 1327 510 350 465 303 455 367 3777

2000 1108 504 399 387 308 363 449 3518

2001 1153 566 494 413 475 523 570 4194

2002 748 664 566 530 566 556 587 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 Domestic One-day First Class Domestic One Day International Test Cricket Total

1999

2000

2001

2002

2003

2004

2005

2006

1819

1732

2685

2685

2685

2685

2598

2598

8658

9048

8892

8892

8580

9438

9126

8892

996 2067 15539

1472 2067 16319

953 1287 15818

909 2379 16867

1386 1248 15902

1386 2691 18204

1039 2262 17030

1559 3042 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 ACB SMA

1996 18.4

1997 14.4

1998 20.8

1999 26.2 37.7

2000 23.6 34.9

2001 21.4 29.7

2

2002 24.2 37.7

2003

2004

2005

2006

31.7

37

27.3

25.1

Sajeel Chaudhry

Figure 1. ACB report on Workload vs. Injury Rate

Player Workload vs. Injury Rate Injury/10000 player hour

5000

30

4000 20

3000 2000

10

1000 0

0 1996

1997

1998

1999

2000

2001

2002

Season

Injury/10000 player hour

Player Designated Matches

Player Matches

Figure 2. SMA report on Workload vs. Injury Rate

Player Workload vs. Injury Rate Injury/10000 player hour

19000

40

18000

30

17000

20

16000 15000

10

14000

0 1999

2000

2001

2002

2003

Season

2004

2005

2006

Injury/10000 player hour

Player Hour Exposure

Player Hour Exposure

Though the above injury rates comprise of all roles and activities within cricket, fast bowling is the activity which is most affected by injuries accounting for over 41% of the total injuries (Gregory, Batt & Wallace, 2004; Stretch, 1993) and hence a moderate to strong correlation can be assumed between the total injury rate of cricketers and of fast bowlers. The reason for a relatively stable injury rate amongst fast bowlers, is due to acknowledgement by the cricketing community that bowlers are required to be in peak physical condition to cope with the demands placed upon them and as a result more scientific physical training programmes have been introduced enhancing performance and reducing the risk of injury by making bowlers stronger and specifically trained for bowling (Woolmer & Noakes, 2008; Noakes & Durandt, 2000). 3

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Performance for a fast bowler is defined as the ability to bowl fast with a relatively low risk of injury (Bartlett et al., 1996). The risk of injury is dependent upon 3 factors (Dennis, 2007): 

Technique



Physical Preparation



Bowling Workload

Out of the above 3 factors, physical preparation is the component which has greatly contributed to the stable state of injury rate over time, as bowling workload has increased over time and change in technique has not been covered in depth with only a handful of studies investigating the efficacy of modifying a fast bowling technique or action (Wallis, Elliot & Koh, 2002; Elliott and Khangure, 2002; Ranson, King, Burnett, Worthington & Shine, 2009). These studies have shown that there are certain aspects of bowling action that can be changed however its effectiveness in elite bowlers is yet to be determined as the actions are highly developed. Based on this evidence the relatively stable rate of injury is due to the recognition that bowlers have become physically more conditioned and stronger over time. Despite the evidence that bowlers have increased their physical condition over time, there seems to be no improvement in the release speed of the ball. Various studies have looked at the strength correlates with the bowling speed of fast bowlers (Wormgoor, Harden & McKinon, 2010; Portus et al, 2004; Pyne et al., 2006) and have predicted variables where strength qualities can be improved to generate greater release speed. Figure 3 shows the stable range of bowling speeds and hence more research is required in understanding this strength and release speed relationship.

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

Top Bowling Speed (km/h) Recorded Over Time 180 160 140 120 100 1975 1976 1976 1979 1979 1992 1997 1998 1999 1999 1999 2000 2000 2000 2000 2000 2001 2001 2001 2001 2001 2001 2002 2002 2002 2002 2002 2002 2002 2002

Bowling Speed (Km/h)

Bowling Speed (KPH)

Time (Year)

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 >150º) 2. Flexed knee (knee angle 150º

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 5

Sajeel Chaudhry

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 Wormgoor et al. Isokinetic strength No significant (2010) test of knee correlation between flexion/extension isokinetic knee strength Pyne et al. (2006)

Isoinertial strength test (Counter Movement Jump)

Loram et al. (2005)

Knee extension/flexion peak torques

Moderate significance between senior and juniors with large effect size (1.4) No significant relationship (extension r = -0.11, flexion r = -0.08)

Findings Negative correlation between knee flexion and release speed, implied knee needs to resist flexion Release speed was greater for greater lower limb strength tests Positive correlation between knee angle and release speed however no strength predictors

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 6

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more flexed knee have thought to have developed their trunk musculature more so to transfer force in a closed kinetic chain. In which case bowlers with a straighter knee may need to increase their trunk strength and force transmission mechanism to increase the release speed whereas the more flexed knee need to concentrate on their knee eccentric ability Similarly no relationship has been investigated between the strength measurements in a kinetic chain and the relative independent movement of the bowling arm during a bowling action at FFC. Burden and Bartlett (1990) showed a strong correlation in the linear speed of the hip and shoulder joints, however a weak correlation between the shoulder and elbow. Since bowling exhibits triple extension patterns within a closed kinetic chain with a proximal to distal firing pattern, a relative independent movement of a particular joint may indicate weakness within the kinetic chain as work by Bai et al., (2008) has shown high correlation between joint movements and muscle activation during an Olympic lift such as a snatch which is highly correlated to athletic performance and efficient closed kinetic chain force production (Funato, Matsuo & Fukunago, 1996). Thus strength correlates such as trunk strengths, leg strength and upper body strengths during such a movement pattern must be investigated. Studies into strength correlates and release speed of the ball have taken a very generalist view of the strength measurements and have failed to address any dominant biomotor abilities within an action. For instance within the three types of knee actions in a bowling technique, where the knee flexes and then extends has greater correlation with the release speed of the ball (Portus et al., 2004). The time to peak force within a bowling action is 16ms from FFC (Hurion et al, 2000) which is similar to the fast stretch shortening cycle of