CHAPTER THREE METHODOLOGY

Transcription

1 CHAPTER THREE METHODOLOGY Subjects A total of twelve, male, students, and studying sport at the University of Wales, Institute Cardiff (UWIC), and members of the university cricket squad participated in the study. All participants had played at the British Universities Sport Association League 2 standard or higher and participated in cricket for more than 5 years. Subjects were all in pre-competition phase of their training, prior to the start of the English cricket season. Mean standard deviation (s) age was years. Each of the subjects were fully informed of the purpose and possible risks of the study, each subject was required to sign a consent form. The university of Wales Institute, Cardiff ethics committee granted human ethical approval for the study. Equipment Testing was conducted in a multipurpose sports hall at UWIC University at Cyncoed campus; it was conducted prior to training programme, and post a 4- week training programme with the weighted balls. For measuring the speed of participant s delivery a hand held calibrated radar gun was used (Bushnell velocity speed gun, , Kansas, USA) with speed recorded in miles per hour (mph). The cricket ball for used for speed testing was a regulation weight men s cricket ball (Tiflex, Liskeard, UK) and was of a brand new, unused condition. The over and underweighted balls used for both the training interventions (Podium balls, Birmingham, UK) were of two different weights categories 176 and 192 grams (g) (+10% and +20%); and 480-g and 128-g (+200% and 20%) variations in weight of the regulation ball (160-g). 1

2 Procedures Subjects participated in an initial speed testing session which involved a thorough warm up, including bodyweight exercises, followed by 10 progressive effort deliveries to raise heart rate and ensure the body was prepared for an allout effort of bowling. Each individual then bowled 12 deliveries with a regulation weight cricket ball with the speed of each delivery being recorded by the radar gun (Bushnell velocity speed gun, , Kansas, USA). The radar gun was situated directly behind the stumps at the bowler s end 2 metres (m) from the backline of the bowling crease. Participants were required after each delivery to collect ball and walk back to beginning of run up to replicate a match realistic rest periods. Participants were then separated randomly in to three groups, a control group (a), an intervention group using 10% and 20% increases in weight of regulation ball (b), and an intervention group participating in a complex training design using a variation of weighted balls (c). The control group (a) were instructed to participate in their university training as usual and no intervention was prescribed. The first intervention group (b) were prescribed a training intervention alongside their university training. The training intervention involved training with increased weight cricket balls 4 sessions a week for 4 weeks, totalling 16 sessions. The sessions were designed to involve progressive overload in the training. The second intervention group (c) were also prescribed a training intervention alongside their university training. The training intervention involved a complex training type design and included training with increased and decreased weighted cricket balls for 4 sessions a week for 4 weeks, totalling 16 sessions (Table 1). 2

3 Table 1. Summary of the training programme prescribed for each group Group Week 1 Week 2 Week 3 Group a N/A N/A N/A Week 4 N/A Group b 4x(6x6x176-g) 4x(8x6x176-g) 4x(6x6x192-g) 4x(8x6x192-g) 4x(2x6x480-g 4x(2x6x480-g 4x(2x6x480-g 4x(2x6x480-g Group c 2x6x160-g 2x6x160-g 2x6x160-g 2x6x160-g 2x6x128-g) 2x6x128-g) 2x6x128-g) 2x6x128-g) After the 4 weeks all groups (a, b and c) were then tested again using the same procedure as previous for their speed of delivery with a regulation ball. Performance Measures Each player was instructed to bowl each of the 12 deliveries at maximum effort and each delivery was then monitored for the speed of the delivery (mph). The ball speed was recorded and relayed by a calibrated radar gun (Bushnell velocity speed gun, , Kansas, USA). This was positioned directly behind the stumps at the bowlers end 2-m from the stumps and measured ball speed at release. Each participant s speed results were then recorded on excel spreadsheet for the purpose of statistical analysis. Statistical Analysis Upon completion of the study, results were then analysed to see if the training interventions with the over and underweighted balls had caused any changes in 3

4 bowling delivery speed. The Data (mean s) from the initial testing was compared with that of post testing to see if there was a significant difference in delivery speed. The three sets of results from the two tests were then input to SPSS analysis software (Statistical Package for Social Science, Chicago, IL), which is recommended for quantitative data analysis (Gratton & Jones, 2004), and run through a paired samples t-test to analyse changes from pre to post training intervention for each group and also a one-way ANOVA to compare any changes across the three groups. The P value was set at 0.05 (twotailed) level of significance, if the mean fell below this figure it was deemed to be significant. Research Design An explanatory approach to the proposed methodology The training intervention for group-b is based on successful studies conducted in baseball and training to increase throwing velocity. The results indicated the most effective variation in weight was to use baseballs within 20% of standard weight. The reason being it duplicates the force-velocity output and full range of motion specific to the competitive throwing and pitching movement patterns (DeRenne, 1985; DeRenne et al., 1994; Escamilla et al., 2000). The intervention for group-c is based on the training principle for speed strength training and is a complex design aiming to target neural and muscular adaptions by putting the bowling action under various resistance and speed changes similar to that used by Harris (1999). It has been suggested that highly specific fast movements could recruit and fire these fast-twitch muscle fibres (Duchateau et al., 2006; Sale, 1987) The variation in weight used in the intervention is an experimental reflection on the type of weight increases used by soviet athletes for decades (Jarver, 1973; Konstantinov, 1979; Verkhoshansky, 1983; Kanishevsky, 1984) with the over-weighted ball being +200% mass than standard and the under-weighted ball being -20% mass than standard. The purpose behind using the weighted ball as a pose to other variations of resistance training is to allow the ROM to reflect the original 4

5 bowling action with; also the allowance for unlimited variation in movement and normal acceleration as indicated by Stone (2002). Other benefits include the performer having the opportunity to improve balance with this type of free-form training as shown in a study by Spennewyn (2008), although this is not being tested within the study. With regards to issues of the chosen methods there are selected areas that are crucial to the results of the study. Firstly the participants have been asked to perform the sessions 4 days a week for 4 weeks, of which 12 of these sessions will not be monitored and will be intrusted to the participant to attend and to perform the set training plan. If participants do not attend all sessions this could have a large effect on the post intervention results, therefore participants have been asked to keep a training diary and report to an online blog at the end of the week to confirm session attendance. The minimal number of completed sessions to have inclusion in the post intervention testing was set at 12, if the participant failed to complete the requirement there results would be deemed invalid and not included in the study. Motivation of the participants during the session was also highlighted to be very important as it could again have an effect the end results. Participants were instructed to deliver each ball at match type intensity with total effort going in to the delivery. To help ensure the participant delivers each ball at maximum effort they had been instructed prior to each delivery to pause and to imagine they are trying to bowl the ball through the net, helping to put total effort in to each individual delivery. Finally a possible issue with the selected method is the total number of weeks the training intervention is implicated for. Many weighted implement studies showing significant increases in throwing velocity have included a training intervention lasting 6 weeks or more (DeRenne, Ho & Blitzblau, 1990 DeRenne et al., 1994; Escamilla et al., 2000). The reason for the selected 4-week intervention is a combination of time available to the participants, the use of facilities and the factor that participants drive to participate may decrease after 4-weeks as they are participating voluntary. In the best possible situation the study would have been conducted for the duration of six weeks of more to give the best opportunity for sufficient training adaptions to occur. 5

6 CHAPTER FOUR RESULTS 6

7 The data collected was analysed and compared for changes from pre intervention to the results collected after 4-weeks, post intervention. Comparissons were made between the results from pre intervention testing and the results post intervention testing. Mean delivery speed, mean peak delivery speed and the percentage fatigue from the peak delivery speed to the mean delivery speed were calculate and results produced (Table 2). Mean Delivery Speed The control group (a) obtained a 0.3% improvement on mean delivery speed with mean s scores of vs mph over the 4-weeks; similar to that of the intervention group using the complex training design consisting of over and under-weighted balls (c), which obtained an improvement of 0.4% on mean delivery speed mean s scores of vs mph. Comparison of the pre and post intervention mean delivery speeds indicated there was no significant change in either group a or c respectively ( P = ³ 0.05). However in the intervention group training with 10% and 20% increments in weight, group (b), there was a 1.5% improvement on mean delivery speed with mean s scores of vs mph; when compared this yeilded a statistically significant improvement ( P = 0.009) (Figure 1). Peak Delivery Speed The control group (a) obtained a 0.7% increase on peak delivery speed with mean s scores of vs mph; the intervention group using 10% and 20% increments in weight (b) also increased with a 0.4% improvement on peak delivery speed with mean s scores of vs mph. There was no change in the intervention group using the complex training design consisting of over and under-weighted balls (c) with mean s scores of vs mph. 7

8 Fatigue Fatigue was presented by calculating the mean delivery speed as a percentage of the peak speed achieved by each group; this was done for both the pre and post intervention testing scores. The control group (a) had an increase of 13.6% in fatigue from pre intervention to post intervention testing with mean s scores of vs % fatigue. Both weighted ball intervention groups (b & c) had a reduction in fatigue post training intervention -31% and % respectively with mean s scores of vs and vs % fatigue (Figure 2). 8

9 % fatigue Mean Delivery Speed (mph) Table 2. Summary of bowling speed data (mean s) (mph) with comparison of Pre to Post intervention change (%) Pre Post % Change between Pre and Post Group Control (a) +10%/+20% (b) +200%/Reg/ -20% (c) Control (a) +10%/+20% (b) +200%/Reg/ -20% (c) Control (a) +10%/+20% (b) +200%/Reg/ -20% (c) Peak Speed Average Speed % Fatigue* Pre Post %/reg/-20% +10%/+20% control group 65 group 64 Pre intervention Post Measurment Period Figure 2. Comparison of fatigue as a percentage of peak delivery speed from pre training intervention testing to post intervention testing across the three groups. Fatigue= 100- (100/peak x mean). 9 Figure 1. Comparison of mean delivery speed from pre training intervention testing to post intervention testing across the three groups.

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