BIOMECHANICS OF CRICKET BOWLING

 

   Recently I came across something on cricket bowling in my old departmental files that may be of interest toanyone who lives in the cricket playing countries of the world. The following preliminary biomechanical analysis carried out by one of our graduate students in the School of Mechanical Engineering at the University of the Witwatersrand on the controversial bowling action of one of South Africa's remarkable spin bowlers, Paul Adams.

  This student has now moved to the University of Cape Town, where he is fortunate to be under the excellent supervision of Dr Kit Vaughan who returned to S Africa after teaching for many years in North America. Apparently he has now extended this work considerably and will be taking this project even further when he completes his Masters in the near future. As a cricket fan of many years' standing and a keen university level player for several years, I look most forward to seeing what emerges from this research. It would be interesting to hear from others of any more up-to-date work that must have been been done on the mechanics of both spin and quick bowling. What is of special interest to me are the kinesiological differences between the delivery actions of cricket bowling and baseball pitching, especially since the ballistic winding up action in baseball seems to produce a large number of 'rotator cuff' injuries. Even if one examines the throwing actions of top cricketing fielders and baseball fieldsmen (not necessarily bowlers or pitchers), the baseballer appears to use a far greater degree of lateral rotation of the humerus. Has anyone here come across a comparison of the normal throwing actions of cricketers and baseballers to ascertain which technique is more efficient and safer? Certainly, the situation and types of delivery are different to suit the rules of the game, but it would still be interesting to have a few more facts and figures about delivery styles as they relate to release velocity, ball control, shoulder integrity and so forth. Any offers?

Dr Mel C Siff

mcsiff@aol.com

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ANALYSIS OF CRICKET BOWLING ACTION OF PAUL ADAMS

  A recent video analysis of the unusual bowling action of South African spin bowler, Paul Adams, carried out during early 1996 in the School of Mechanical Engineering at the University of the Witwatersrand by postgraduate student, Dudley Tabakin, under the supervision of senior lecturer, Dr Mel Siff, revealed that a degree of elbow straightening may well be one of the secrets which allows Paul to impart remarkable spin to the ball. This preliminary study constituted the first scientific analysis of the controversial Adams action and should help the cricketing fathers replace current speculation with some hard evidence. During the previous year, Siff, in examining the differences between baseball pitching and cricket bowling, had noticed what appeared to be a definite type of throwing action by Adams, that differed significantly from that of other international spinners with apparent ‘chucking’ actions, so, when Tabakin approached him about pursuing a Masters degree in biomechanics, Dr Siff suggested that he carry out a scientific analysis of the differences between the delivery actions in cricket and baseball. Tabakin began by analysing available video footage of Paul's bowling recorded during the recent matches between South Africa and England in South Africa, as well as on recordings of overs that Paul bowled against the West Indies. Joint markers were identified on the neck, shoulder, elbow and wrist and these were digitised for every sequence of frames. He then analysed the data on a computer to determine the different joint angles for each bowling delivery. Some of the resulting graphs had to be discarded because they were either difficult to interpret or inaccurate. The example below offered one of the clearest and most accurate analyses of this video material.

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Point A marks the end of the preparatory and final winding up stage which characterises Paul's unique action. Here the elbow is thrust strongly backwards until it reaches its minimum value of 22 degrees. Since the triceps muscle crosses the elbow and shoulder joints, this action prestretches the triceps muscle and appears to allow Paul to subsequently use the stored elastic energy in this muscle to deliver a sharp thrust during the final straightening of his elbow. His arm continues to move backwards and upwards from position A until it reaches a point B diagonally behind his head where the major twisting action of his arm begins. His elbow angle at this point is 151 degrees. The twisting of all the joints of his arm (upper extremity) continues until the ball is released at point C, when his elbow angle has increased to 170 degrees. In other words, between points B and C, he has straightened his elbow by 19 degrees. According to the laws of cricket, the bowler may not change the angle of the elbow during the final delivery stage, so that this video analysis would imply that this action should be deemed to be throwing. Dr Siff considers that, because the 'anti-chucking' law was originally instituted to prevent fast bowlers from gaining an unfair speed advantage by bending and straightening the elbow, far less attention was paid to the spinning advantage offered to spin bowlers by this type of elbow action. Since elbow flexion allows the forearm to impart far greater spin to the ball (and better disguise of the action), even if the elbow is not straightened during delivery, while comparable slight elbow straightening by a fast bowler offers only a small increase in speed, it appears that a bent elbow offers a much greater advantage to a spinner than a fast bowler. This preliminary analysis suggests either that umpires adopt a stricter view towards spinners or that the laws of cricket be modified to allow some elbow straightening by all bowlers (provided that the elbow is not allowed to provide a sideways 'chucking' action). Dudley is currently analysing many types of throwing and bowling actions as part of his Master's degree to offer scientific guidelines to the cricketing community concerning this problem. By the time that he has studied sufficient footage of Adams and other local and international spinners and quick bowlers, it is hoped that the cricketing world will be enriched by a better understanding of the different types of bowling action. Possibly this sort of analysis will even assist the cricketing fraternity in modifying and applying the laws of the game. The aphorism, "It’s not cricket", may then take on a entirely new meaning!

[ School of Mechanical Engineering, University of the Witwatersrand, Johannesburg 19 March 1996 ]

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