This thesis sought to reveal the physical and kinematic determinants of pace bowling performance. After drawing on these determinants, a secondary aim was to investigate whether pace bowling performance could be enhanced with chronic resistance training and warm-up strategies. However, before the physical and kinematic determinants of pace bowling performance could be identified, and the effects of two training interventions and warm-ups on pace bowling performance, a new pace bowling test was created, and the test-retest reliability of its performance and kinematic measures were evaluated.
Knowledge of a variables’ test-retest reliability is important for interpreting the validity of correlations, but also for the determination of a meaningful change following a training intervention. Only one published study to date has explored the test-retest reliability of a pace bowling assessment, and this test only measured bowling accuracy (1). Previous research has not comprehensively examined the relationships between physical qualities and pace bowling performance. Several important physical qualities (e.g., power, speed-acceleration, flexibility, repeat-sprint ability) have been excluded in correlational research, which may be crucial for optimal pace bowling performance. Furthermore, there is only one published training intervention study on pace bowling research (2). Consequently there is scant evidence for coaches to design training programs proven to enhance pace bowling performance. Baseball pitching studies have trialled the effects of heavy-ball throwing in the warm-up on subsequent throwing velocity and accuracy, but this approach has not been studied in cricket pace bowling, especially after several weeks of training. Therefore, four studies were conducted in this PhD project to address these deficiencies in the literature.
The purpose of Study 1 (Chapter 3) was to ascertain the test-retest reliability of bowling performance measures (i.e., bowling speed, bowling accuracy, consistency of bowling speed, and consistency of bowling accuracy) and selected bowling kinematics (i.e., approach speed, step length, step-length phase duration, power phase duration, and knee extension angle at front-foot contact and at ball release) in a novel eight-over test, and for the first four overs of this test. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and coefficient of variation (CV) were used as measures of test-retest reliability (3). Following a three week familiarisation period of bowling, 13 participants completed a novel eight-over bowling test on two separate days with 4–7 days apart. The most reliable performance measures in the bowling test were peak bowling speed (ICC = 0.948–0.975, CV = 1.3–1.9%) and mean bowling speed (ICC = 0.981–0.987, CV = 1.0–1.3%). Perceived effort was partially reliable (ICC = 0.650–0.659, CV = 3.8–3.9%). However, mean bowling accuracy (ICC = 0.491–0.685, CV = 12.5–16.8%) and consistency of bowling accuracy failed to meet the pre-set standard for acceptable reliability (ICC = 0.434–0.454, CV = 15.3–19.3%). All bowling kinematic variables except approach speed exhibited acceptable reliability (i.e., ICC > 0.8, CV < 10%). The first four overs of the bowling test exhibited slightly poorer test-retest reliability for all measures, compared to the entire eight-over test. There were no systematic biases (i.e., p > 0.05) detected with all variables between bowling tests, indicating there was no learning or fatigue effects. The smallest worthwhile change was established for all bowling performance and kinematic variables, by multiplying the SEM by 1.5 (4). It is recommended that the eight-over pace bowling test be used as a more comprehensive measure of consistency of bowling speed and consistency of bowling accuracy, as bowlers are more likely to be fatigued. However, if coaches seek to assess pace bowlers in shorter time, delimiting the test to the first four overs is recommended. Both versions of the pace bowling test are only capable of reliably measuring bowling performance outcomes such as peak and mean bowling speed, and perceived effort.
The second study of this PhD project examined the relationships between selected physical qualities, bowling kinematics, and bowling performance measures. Another purpose of this novel study was to determine if delivery instructions (i.e., maximal-effort, match-intensity, slower-ball) influenced the strength of the relationships between physical qualities and bowling performance measures. Given that there were three delivery instructions in the bowling test, an objective of this study was to explore the relationship between bowling speed and bowling accuracy (i.e., speed-accuracy trade-off). Thirty-one participants completed an eight-over bowling test in the first session, and a series of physical tests, spread over two separate sessions. Each session was separated by four to seven days. Mean bowling speed (of all pooled deliveries) was significantly correlated to 1-RM pull-up strength (rs  = 0.55, p = 0.01) and 20-m sprint time (rs  = -0.37, p = 0.04), but the correlations marginally increased as delivery effort increased (i.e., maximal-effort ball). Greater hamstring flexibility was associated with a better consistency of bowling speed, but only for a match-intensity delivery (rs  = -0.49, p = 0.01). Repeat-sprint ability (i.e., percent decrement on 10 × 20-m sprints, on every 20 s) displayed a stronger correlation to consistency of bowling speed (rs  = -0.42, p = 0.06) than for mean bowling speed (rs  = 0.15, p = 0.53). Bench press strength was moderately related to bowling accuracy for a maximal-effort delivery (rs  = -0.42, p = 0.03), with weaker but non-significant (p > 0.05) correlations for match-intensity and slower-ball deliveries. Bowling accuracy was also significantly related to peak concentric countermovement jump power (rs  = -0.41, p = 0.03) and mean peak concentric countermovement jump power (rs  = -0.45, p = 0.02), with both physical qualities displaying stronger correlations as delivery effort increased. Greater reactive strength was negatively associated with mean bowling accuracy (rs  = 0.38, p = 0.04) and consistency of bowling accuracy (rs  = 0.43, p = 0.02) for maximal-effort deliveries only.
Faster bowling speeds were correlated to a longer step length (rs  = 0.51, p < 0.01) and quicker power phase duration (rs  = -0.45, p = 0.01). A better consistency of bowling accuracy was associated with a faster approach speed (rs  = -0.36, p = 0.05) and greater knee flexion angle at ball release (rs  = -0.42, p = 0.03). No speed-accuracy trade-off was observed for the group (rs  = -0.28, p = 0.12), indicating that most bowlers could be instructed to train at maximal-effort without compromising bowling accuracy. Pull-up strength training and speed-acceleration training were chosen for the “evidence-based” training program (Study 3). Heavy-ball bowling was also considered as part of the evidence-based training program, as it is a specific form of training used previously, and because there was a shortage of significant relationships (p < 0.05) between physical qualities and bowling performance measures in Study 2.
The third investigation of this PhD project compared the effects of an eight-week evidence-based training program or normal training program (not a control group) on pace bowling performance, approach speed, speed-acceleration, and pull-up strength. Participants were matched for bowling speed and then randomly split into two training groups, with six participants in each group. After an initial two-week familiarisation period of bowling training, sprint training, and pull-up training, participants completed two training sessions per week, and were tested before and after the training intervention. Testing comprised the four-over pace bowling test (Study 1), 20-m sprint test (Study 2), and 1-RM pull-up test (Study 2). In training, the volume of bowling and sprinting was constant between both groups; the only differences were that the evidence-based training group bowled with heavy balls (250 g and 300 g) as well as a regular ball (156 g), sprinted with a weighted-vest (15% and 20% body mass) and without a weighted-vest, and performed pull-up training. Participants were instructed to deliver each ball with maximal effort in training, as no speed-accuracy trade-off was observed for the sample in Study 2. The evidence-based training group bowled with poorer accuracy and consistency of accuracy, with only a small improvement in peak and mean bowling speed. Heavy-ball bowling may have had a negative transfer to regular-ball bowling. Although speculative, a longer evidence-based program may have significantly enhanced bowling speed. Coaches could use both training programs to develop performance but should be aware that bowling accuracy may suffer with the evidence-based program.
The evidence-based training group displayed slower 20-m sprint times following training (0.08 ± 0.05 s). However, the normal training group was also slower
(0.10 ± 0.09 s), indicating the potential for speed-acceleration improvement is compromised if speed training is performed immediately after bowling training; most likely due to residual fatigue. Consequently it is recommended that speed-acceleration training be conducted when bowlers are not fatigued, in a separate session, or at the beginning of a session.
The evidence-based training group improved their 1-RM pull-up strength by
5.8 ± 6.8 kg (d = 0.68), compared to the normal training group of 0.2 ± 1.7 kg (d = 0.01). The difference between training groups is due to the fact that the normal training group were not prescribed pull-up training. As many participants could not complete the pull-up exercise due to insufficient strength, the dumbbell pullover may be a suitable alternative that is more specific to the motion of the bowling arm (i.e., extended arm).
The fourth study of this PhD project explored the acute effects of a heavy-ball bowling warm-up on pace bowling performance, and determined if these acute effects could be enhanced or negated following an evidence-based training program. This study involved the same participants who completed the evidence-based training program in Study 3. These participants were required to perform two different bowling warm-ups (heavy-ball or regular-ball) in pre and post-test period, followed by the four-over pace bowling test (Study 1). In pre-test period, bowling accuracy was 8.8 ± 7.4 cm worse for the heavy-ball warm-up compared to the regular-ball warm-up (d = 1.19). In post-test period however, bowling accuracy was 5.5 ± 6.4 cm better in the heavy-ball warm-up compared to the regular-ball warm-up (d = -0.90). A similar trend was observed for consistency of bowling accuracy. These findings indicate that pace bowlers adapt to heavy-ball bowling, and bowl more accurately with a regular ball if they warm-up with a heavy ball first (but only after eight weeks of heavy-ball training). Coaches could employ a heavy-ball warm-up prior to training or a match, but only after eight weeks of evidence-based training. It is hypothesised that a less biomechanically similar exercise to the pace bowling motion such as resisted push-ups / bench press throws could be more effective in eliciting potentiation by activating higher order motor units without negatively transferring to bowling performance.
From the studies presented in this thesis, it is concluded that peak and mean bowling speed are the most reliable bowling performance measures, and all kinematic variables apart from approach speed possess excellent reliability. Furthermore, 1-RM pull-up strength and 20-m speed are significantly correlated to bowling speed. An evidence-based training program can develop peak and mean bowling speed, but the cost to bowling accuracy and consistency of bowling accuracy does not make this training program worthwhile in enhancing pace bowling performance. A heavy-ball warm-up impairs bowling accuracy and consistency of bowling accuracy compared to the regular-ball warm-up, but only prior to training with the heavier balls. Pace bowlers adapt to heavy-ball bowling after eight weeks of training, but must use the heavy balls in the warm-up to bowl more accurately with a regular ball, otherwise pace bowling performance is below optimal.