 a professor in sports physiotherapy at the University of the Witwatersrand, Johannesburg, South Africa and the director of the Witt's Cricket Research Hub for science medicine and rehabilitation. I have a special interest in cricket science medicine and rehabilitation and the bulk of my time when it comes to research is spent on working with cricket projects, whether it's supervising students in cricket or collaborating with other institutions on various cricket projects or working with cricket South Africa's Fast Bowlers. Then I love creating new resources for researchmasterminds.com and my research masterminds YouTube channel. It's research resources for postgraduate students, academics, early career researchers. So just to build some more anticipation before we get into the actual presentation, I'd like to introduce you to the Witt's Cricket Research Hub for science medicine and rehabilitation. 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In this presentation I'd like to share with you some of the insights around the topic of abdominal muscle thickness as measured via specifically ultrasound imaging and its role in injury and performance and how we got to the conclusion that asymmetry in internal muscle oblique thickness is not the key to the force bowler's performance. So for now this is our conclusion but I'm saying for now because at this stage it looks like the internal oblique muscle does not play a role in the force bowler's performance. However, much more research needs to be done before we can rest this conclusion down in peace. In this presentation I'll focus on the findings related to the internal oblique muscle but I urge you to locate the papers that I'll be referring to and read up on the findings related to the external oblique transversus abdominis and multifidine muscles. Also note that this presentation focuses on the side-to-side differences, the symmetry and asymmetry and not on the actual thickness and its relationship with bowling performance. In crickets the force bowling action is a repetitive asymmetrical action during which the one arm extends above the head and at the same time the trunk goes into extension flexion lateral flexion and often near the end of the anatomical range of movement. So ground reaction forces and consequently lambda spine segment loads are at their highest during the power phase between front foot contact and ball release of the bowling action. The inherent nature of the force bowling action predisposes the bowler's injury while allowing for the high ball release speeds to be attained. The bowling performance of a cricket force bowler is judged in terms of the speed in which the ball can be delivered and how accurately the delivery is placed in relation to the wickets behind the batsman on strike. So various of the intrinsic determinants of ball release speed and accuracy have been explored in the literature including anthropometrics, bowling biomechanics, run-up velocity, lower body strength and trunk muscle stability. However the side-to-side differences in the thickness of the abdominal muscles and lumbar motifidae have not been explored. What we mean here is that this asymmetry in muscle morphometry asymmetry in the muscle thickness have not been explored as a possible determinant of ball ball release speed and accuracy. Before we dive into the research let's have a look at the internal oblique muscle itself. So the internal oblique muscle sits at the side on the side of the trunk and it runs from the ribs to the pelvis. Now it's responsible for side flexion or rotation and of course it works with the other abdominal muscles and these are just two of the functions of the internal oblique that I've just mentioned. So you can imagine that if you have a right-handed force bowler that this left internal oblique will work quite a bit when it comes to the repeated bowling action of side flexion and rotation. So what do we know? We know that as a result of this asymmetrical bowling technique which is actioned repeatedly asymmetry in the morphometry particularly in terms of the thickness of force bowler's abdominal muscles is a common phenomenon. So amongst injury-free force bowlers the internal oblique of the non-dominant side is often thicker than that of the dominant side. In this study we explored the side to side asymmetry in absolute and relative muscle thickness in specifically injury-free cricket force bowlers. We assessed 26 right-handed force bowlers and we measured the muscle thickness of the abdominal muscles using ultrasound. We measured them both at the start and the end of the cricket season and we found that the non-dominant internal oblique muscle was thicker than the dominant internal oblique muscle both at the start as well as at the end of the cricket season. Now studies done by Martin et al and Gray et al also found that the internal oblique was thicker on the non-dominant side in force bowlers without pain. So the asymmetry in muscle thickness can be explained by sport-specific muscle adaptation associated with the repetitive rotational demands of the bowling action. The force bowling action involved trunk flexion, rotation and side flexion towards the non-dominant side during the delivery stride and this seems to induce this hypertrophy due to the high loading of the musculature on the non-dominant side and it's possible that the type of bowling action utilized plays a role in the asymmetry detected in the internal oblique muscle. In other words the non-dominant internal oblique may hypertrophy to protect the bowler against potentially harmful kinetic and kinematic movement components during the bowling action such as this contralateral lumbar pelvic side flexion and the body seems to adapt without compromising on these on ball release speeds in this case. However future research is needed to explore this hypothesis considering that a more symmetrical internal oblique in other studies was associated with lower back and lower limb injury and we'll get to that just now. Previous research also tells us that bowlers who were injury-free at the time of testing but who went on to sustain an injury during the cricket season showed no side-to-side differences in terms of thickness of the internal oblique muscle. So we went on to do some further explorations and in this study we investigated abdominal muscle thickness in injury-free adolescent forced bowlers. We included 28 injury-free cricket forced bowlers into the study and we assessed the the thickness of the abdominal muscles at the start of the cricket season and then we observed them as they went on to play during the season and we monitored their injuries and some remained injury-free and others sustained injuries. We found that the thickness of the internal oblique muscle on the non-dominant side was greater than that on the dominant side in these cricket forced bowlers. Now remember all forced bowlers were injury-free at the start of the season when they were assessed and those who remained injury-free for the entire season in other words they displayed an asymmetry in internal oblique muscle. While the opposite was true for those who went on and sustained injuries those players showed a symmetry in internal oblique as measured at the start of the season at the time when these players were also injury-free. So this alludes to some role that the symmetry or asymmetry of the internal oblique muscle plays in relation to low back and low limb injury. We also know that forced bowlers experienced low back pain at the time of testing also displayed a more symmetrical internal oblique muscle thickness. Let's have a look at this study by Gray et al on abdominal morphology in forced bowlers. Gray et al included 25 forced bowlers into their study so 16 of them had low back pain and nine was without low back pain and they measured the abdominal thickness also via ultrasound and it was a cross-sectional study. So in this study some had low back pain and some did not have low back pain while in the previous study all bowlers were injury-free and in the previous study of martin et al some went on to sustain injury later but the assessment was done at the time that they were injury-free. So in this case we were working and looking at forced bowlers who already experienced pain and the same finding came out of this study so that the thickness of internal oblique was greater on the non-dominant side for participants without low back pain but the thickness did not differ between sides it was in other words symmetrical in bowlers with low back pain. We know now that injury-free forced bowlers have a thicker internal oblique on the non-dominant side than on the dominant side we also know that forced bowlers who initially were injury-free but goes on to sustain an injury during the season displays a more symmetrical internal oblique and we know that forced bowlers with low back pain have got a more symmetrical internal oblique muscle. So the link between trunk muscle thickness as measured through ultrasound and injury has been determined but no evidence exists for the relationship between trunk muscle thickness and bowling performance so it's crucial to determine this link specifically in the context of the unique sporting demands of the forced bowler forced bowlers main aim is to perform well on the field so to deliver the ball in a way that makes it difficult for the batter to accurately address the delivery while remaining injury-free to optimize bowling performance so therefore it's important to explore both the link between side-to-side differences in trunk muscle thickness and injury as well as the relationship between these same side-to-side differences in trunk muscle thickness and performance in other words borely speed and accuracy in order to get a realistic view so in association or the lack thereof between bowling performance and trunk muscle thickness can form the basis of future research where cause and effect can be established. We therefore decided to have a look at the internal oblique muscle specifically the side-to-side difference in internal oblique and its role in bowling performance namely borely speed and accuracy we conducted an observational cross-sectional study including forced bowlers between the ages of 13 and 18 years at the schools out on net we measured their borely speed using a radar gun we had an accuracy target to measure bowling accuracy and we measured the ultrasound imaging of the abdominal muscles specifically muscle thickness using an ultrasound imaging system 46 injury-free forced bowlers participated and we found the typical side-to-side differences at rest where the internal oblique on the non-dominant side was thicker than that on the dominant side for with these injury-free forced bowlers but we also found no relationship between borely speed or accuracy and these side-to-side differences just to emphasize in this presentation the focus is not on the actual muscle thickness and its relationship with borely speed and accuracy but the focus is on the side-to-side differences in the symmetry or asymmetry and its role in bowling performance borely speed and accuracy and in the from this table you can see that none of the side-to-side differences and the various calculations that we've done were linked to borely speed or accuracy so the side-to-side differences in internal oblique was not associated with borely speed while this muscle has been implicated in earlier work for its potential role in injury specifically lower back and lower limb injury and when it comes to accuracy seeing that the trunk muscle contribute to the proximal stability we hypothesized that some relationship will exist however it's possible that a more involved measure of accuracy is required to adequately explore this relationship such as the combination of accuracy target behind the stamps and one on the pitch also it may be that the mechanism other than side-to-side differences in muscle thickness or determinants of accuracy so no literature exists relating the accuracy to trunk muscle morphometry and therefore future research is definitely warranted to explore this interaction a bit further future research needs to explore the effect of an intervention program to enhance the asymmetry of the internal oblique muscle for injury prevention purposes while we do not foresee an influence on borely speed or accuracy it is important to consider this potential trade-off as it is present in other domains of fast bowling where a technique related factor involving for example the knee angle is associated with injury and at the same time with higher borely speed so and this is an important component because if we consider this trade-off if a fast bowler are being given either a technique modification or an exercise to prevent injury but this intervention is going to impact on their performance borely speed and accuracy the chances that they're going to go through with this exercise or intervention or technique modification and while tolerating a lower level of performance it's low so we need to consider this trade-off between injury prevention and performance in everything we do and everything we prescribe now this little video clip is from one of the studies that we've done in our lab using an inertial measurement system the XN system and we are continuously exploring the biomechanics of the fast bowling action the including women's cricket and injury surveillance so we're excited about the future what the future holds for our Witt's cricket research up in conclusion we now know that injury-free fast bowlers present with a thicker internal oblique muscle on the non-dominant side we also know that this asymmetry in internal oblique muscle thickness may be protective against injury or at the very least it is associated with being injury free and now we also know that the side-to-side differences in terms of internal oblique thickness is not associated with bowling performance measures such as borely speed and accuracy it is important to investigate the factors associated with injury together with the factors associated with performance the fast bowler would like to perform at their best while remaining injury free and therefore these two factors associated with performance and injury prevention measures should not be divorced from one another i would like to acknowledge the co-authors in the studies referred to in this presentation Franz-Marie Willefier, Labath Obiora, Nkarsine Gooney, Candice McMillan, Natalie Benjamin-Damons, Warwick Mickenin and Amy Stewart thank you very much for your contributions they are all co-authors on the work that we published as part of our cricket research here at the University of the Wittwatersrand and i'm grateful for their contributions i would also like to thank the Faculty Research Committee and the National Research Foundation for financially supporting some of the work that we've done thank you very much for joining me on this journey where we explored the thickness of the internal oblique muscle and its role in performance and injury in fast bowlers if you would have any questions or you would like to suggest an exciting collaboration feel free to send me an email bonitowillefier at witts.ac.ca you can also follow me on researchgate and also please follow the social media channels and have a look at our website from the Witts Cricket Research Hub for science medicine and rehabilitation also if you would like to get some research inspiration follow the research masterminds social media channels and subscribe on the research masterminds youtube channel keep well and stay happy