Letter addressed to Duleep Mendis [Team Manager, Sri Lankan Cricket Team], 19 January 1996
Firstly, we should mention t hat to accurately measure the angle of the elbow during the delivery stride; a number of simultaneous views would need to be recorded (probably a minimum of three), much labour intensive post-processing would be required and even so a number of assumptions would still need to be made. Therefore, due to time and financial constraints rather than carry out a full quantitative three-dimensional analysis, we performed a qualitative, two dimensional analvsis.
Muralitharan was filmed bowling three off-spinners and one leg-spinner at six different views (ie. 24 deliveries) using a standard video camera and high speed cinematography (200 frames per second). The views were as follows :-
1. Side-on (On-side).
4. From where the central umpire would stand.
5. Mid-on (approx.3 0oa round from the central umpire).
6. Directly in front.
The analysis of Muralitharan’s o ff-spinner w as undertaken b y examining each of the above views. After examining views 1-3, it was difficult to assess the legality of his action. From view 4 it was clear that the arm was bent during the delivery arc of his bowling arm, however, the arm appeared to straighten just prior to release. From view 5, however, it was clear that this apparent straightening of the bowling arm was a visual illusion. From this view, Muralitharan’s arm had remained bent, at his full elbow extension throughout the delivery action Further, with respect to Muralitharan’s leg spinner, all views indicated that he does not extend his arm, therefore his leg spinning action is also legitimate.
The results of these analyses indicate that Muralitharan does not straighten his arm whilst bowling either his off- or leg- spinner during the delivery, however, whether the action changes under the pressure of match conditions is debatable. Our opinion is that this would probably not be the case, but this does not preclude this from being a possibility.
We also measured the maximum extension angle of Muralitharan’s elbow and found that he cannot fully extend his elbow beyond 26″ flexion. Further, there is a 15% radial deviation when the elbow is fully extended. The functional consequences of this are that under dynamic motion it would be impossible for Muralitharan to fully extend unless t heir was some damage to his elbow.
lf you have any questions regarding this analysis pleased o not hesitate to contact us.
SIGNED: David Lyold PhD, Lecturer in Biomechanics
Angus Burnett, BPE (Hons.) PhD Student Biomechanics
Daryl Foster, MEd, Coach K ent County C ricket C lub