A kinanthropometric analysis of accurate and inaccurate kickers: Implications for kicking accuracy in Australian football

A paucity of research exists investigating the potential relationship between the technical and temporal strategy of accurate and inaccurate kickers in response to physical parameters modifiable by athletic conditioning. While recent studies have produced improvements in performance when kicking for distance following structured resistance training interventions, no studies have examined the influence of such interventions on the enhancement of kicking accuracy. It was therefore the purpose of this thesis to extend scientific understanding of those mechanisms which might underpin accurate kicking performances through examining kinanthropometric, strength and muscularity profiles of accurate and inaccurate kickers in Australian Football using a series of research studies. In particular, studies one and two established valid and reliable measurement protocols, while studies three, four and five quantified whole-body composition, anthropometrics, segmental masses of the lower limbs, unilateral and bilateral lower-body strength, and lower limb kinematics during the drop punt. Study one established a standardised and reliable body positioning and scan analysis model using Dual Energy X-ray Absorptiometry (DEXA) to accurately identify and assess appendicular segmental mass components (upper arm, forearm, hand, thigh, shank and foot segments); producing very high intra-tester reliability (CV ≤ 2.6%; ICC ≥ 0.941) and very high inter-tester reliability (CV ≤ 2.4%; ICC ≥ 0.961). This methodological determination of intralimb and interlimb quantities of lean, fat and total mass could be used by strength and conditioning practitioners to monitor the efficacy of training interventions; track athletes during long-term athletic development programs; or identify potential deficiencies acquired through-out injury onset and during rehabilitation. Study two assessed a portable isometric lower-body strength testing device, successfully demonstrating its ability to derive valid and reliable representations of maximal isometric force (peak force) under bilateral and unilateral conditions (CV ≤ 4.7%; ICC ≥ 0.961). This device was unable to reliably determine rate of force development across either bilateral or unilateral conditions (CV: 14.5% - 45.5%; ICC: 0.360 – 0.943); and required an extra second of contraction time to achieve peak force (p \u3c 0.001). The portable apparatus may provide a more sport-specific assessment of maximal strength in sports where balance is an important component; such as the support leg during the kicking motion. Using the methodological approach established in study one; study three was a descriptive study which assessed the lower limb segmental profile of accurate and inaccurate kickers. A noticeable difference in leg mass characteristics was evident, with accurate kickers containing significantly greater quantities of relative lean mass (p ≤ 0.004; r = 0.426 to 0.698), significantly lower quantities of relative fat mass (p ≤ 0.024; r = -0.431 to -0.585), and significantly higher lean-to-fat mass ratios (p ≤ 0.009; r = 0.482 to 0.622) across all segments within both kicking and support limbs. To examine how these lower limb characteristics might adjust biomechanical strategy; study four used the methodological approach from study one in conjunction with three-dimensional kinematic data. No relationship was found between foot velocity and kicking accuracy (r = -0.035 to -0.083). Instead, it was the co-contribution of leg mass and foot velocity which were discriminatory factors between accurate and inaccurate kickers. A significant and strong correlation was also found between relative lean mass and kicking accuracy (p ≤ 0.001; r = 0.631). Greater relative lean mass within accurate kickers may heighten limb control due to reduced volitional effort and lower relative muscular impulses required to generate limb velocity. Study five - the final study of the thesis - assessed lower limb strength and muscularity using methodologies presented in studies one and two. Study five was able to successfully demonstrate a positive relationship between relative bilateral strength and support-leg unilateral strength with kicking accuracy outcomes (r = 0.379 to 0.401). A significant negative relationship was established between strength imbalances and kicking accuracy (p = 0.002; r = 0.516), supported by the significant positive relationship between the limb symmetry index for lean mass quantities and kicking accuracy outcomes (p = 0.003 to 0.029; r = 0.312 to 0.402). This highlighted the potential benefit of greater limb symmetry for strength and muscularity between kicking and support limbs within Australian Footballers, with particular emphasis placed toward support leg strength. The general conclusion provided by the thesis promotes the importance and positive influence of relative lean mass and lower body strength to kicking accuracy production during the drop punt. The findings provide a valid rationale for strength and conditioning professionals and skill acquisition coaches to properly consider an athlete’s strength, muscularity and body mass profiles when attempting to improve kicking performance. Given the cross-sectional nature of the Thesis, longitudinal resistance training studies should be attempted in future, to establish interventions which may heighten athletic conditioning and technical proficiency in football sports, with an express aim to improve drop punt kicking accuracy

Biomechanical predictors of ball velocity during punt kicking in elite rugby league kickers

Punt kicking is integral to the attacking and defensive elements of rugby league and the ability to kick the ball with high velocity is desirable. This study aimed to identify important technical aspects of kicking linked to the generation of ball velocity. Maximal punt kicks were obtained from six elite rugby league kickers using a 10-camera motion capture system. Three-dimensional kinematics of the lower extremities was obtained. Regression analysis with ball velocity as criterion was used to identify the kinematic parameters associated with the development of ball velocity. The regression model yielded an adj R2¼0.76, p�0.01. Two parameters were identified: knee extension angular velocity of the kicking limb at impact (R2¼0.50) and peak flexion angular velocity of the kicking hip (R2¼0.26, p�0.01). It is conceivable that players may benefit from exposure to coaching and strength techniques geared toward the modification of kicking mechanics specific to this stud

CENTRE OF MASS MOTION DURING THE PUNT KICK

Centre of mass (COM) motion has been linked to performance in kicking and cricket bowling. The aim of this study was to examine COM motion during the punt kick. Five elite Australia Footballers performed maximal and sub-maximal punt kicks. Optotrak Certus (200Hz) collected kinematic data and COM and foot speed were calculated. Greater COM deceleration was linked to faster foot speeds. Large effects existed between maximal and sub-maximal kicks for change in COM velocity and average impulse as well as for correlations between these parameters and foot speed within the maximal kick. Approach speed was significantly larger for maximal kicks but the relationship was unclear with a negative correlation with foot speed existing within maximal kicks. More work with larger N examining COM deceleration is recommended

Physical and technical demands and preparatory strategies in female field collision sports: a scoping review

Women’s participation in field collision sports is growing world- wide. Scoping reviews provide an overview of scientific litera- ture in a developing area to support practitioners, policy, and research priorities. Our aim is to explore published research and synthesise information on the physical and technical de- mands and preparation strategies of female field collision sports. We searched four databases and identified relevant published studies. Data were extracted to form (1) a numerical analysis and (2) thematic summary. Of 2318 records identified, 43 studies met the inclusion criteria. Physical demands were the most highly investigated (n = 24), followed by technical demands (n = 18), tactical considerations (n = 8) and preparatory strategies (n = 1). The key themes embody a holistic model contributing to both performance and injury prevention outcomes in the context of female field collision sports. Find- ings suggest a gender data gap across all themes and a low evidence base to inform those preparing female athletes for match demands. Given the physical and technical differences in match-demands the review findings do not support the generalisation of male-derived training data to female athletes. To support key stakeholders working within female field collision sports there is a need to increase the visibility of female athletes in the literature.<br/

Investigating the Influence of Ball Orientation on the Foot–Ball Interaction in Rugby Union Place Kicking

Rugby Union place kicking contributes 45% of all points scored and 5.7% of matches are decided by a single kick (Quarrie and Hopkins, 2015). Biomechanical investigations of the place kick have often focused on the movements of the kicker without consideration of how the ball is orientated on the tee and whether that might interact with the kicker’s technique. Therefore, the overall aim of this thesis was to investigate how ball orientation interacts with kick technique and performance to inform the ball setup preferences of kickers. An initial study identified the ball orientation preferences of international kickers at the 2019 Rugby World Cup and assessed kick performance when kicks were categorised by ball orientation. Binomial logistic regression analysis, which also accounted for additional situational factors, revealed that kicks taken with a slanted orientation (approximately 45°) had a greater predicted kick success (90.0%) than with a forward orientation (approximately 15°; 84.4%) and a horizontal orientation (approximately 75°; 86.8%). The second study experimentally altered ball orientation to investigate the effects on kickers’ technique, impact characteristics and resulting kick performance. There were few clear effects of ball orientation on the kicking foot swing plane characteristics or the kicking leg shank and foot segment orientations at initial foot–ball impact, suggesting that each kicker maintained relatively consistent ‘end-point’ characteristics of technique. However, impact location on the ball generally varied significantly (p < 0.05) with ball orientation and when kickers struck the ball closer to the belly, impact efficiency was typically improved. This thesis provides information which could help to inform the ball orientation preferences of place kickers and coaches. There does not appear to be one ball orientation that results in the best performance for all kickers, but exploration of a ball orientation which encourages impact nearer the belly may improve impact efficiency

To investigate bilateral kicking accuracy in ladies Gaelic football

Background Kicking accurately is essential in Gaelic games, and players who kick proficiently with both feet are viewed as highly skilled athletes. Bilateral ability in asymmetrical sport is a potentially advantageous and has been shown to be a key indicator to successful outcomes in games. While research has been done in other sports, very little is known about kicking accuracy among Ladies Gaelic Football Association (LGFA) footballers. The aim of this study is to investigate bilateral kicking accuracy in Ladies Gaelic Football. A secondary aim of this study is to analyse kicking accuracy within games in Ladies Gaelic Football. Methods Notational analysis was used to analyse the various forms of kicking in Ladies Gaelic Football. A total of 15 LGF pre-recorded games were analysed with a view to exploring the use of bilateral kicking in Ladies Gaelic games, and to investigate the role of kicking accuracy in successful game outcomes. A testing protocol to assess bilateral kicking performance in LGF players was developed. Kicking accuracy was measured in both dominant and non-dominant leg at a variety of angles from a distance of 20 meters. The assessment entailed two trials, one in which participants took all their kicks in sequential order, and another where they kicked in a randomised order. Results The results show that there are an average of 196 kicks in LGF games. The results show that significant differences exist between overall kick passing accuracy (p = .024 with a large effect size (η 2 = .17).), as well as significant differences in shooting accuracy (p = .012 with a large effect size (η2 = . 21)) between winning and losing teams. Further findings show that the dominant foot shooting performance was significantly greater than the non-dominant foot kicking performance. For both the controlled and the Randomised test all angles were more accurate on the dominant foot. For example, Angle A between the controlled dominant (Mean = 3.25 ±1.070) and the controlled non-dominant (Mean 1.65 ±1.348) there was a significant difference ( p < 0.000 (two-tailed) η 2= 0.53, which is a large effect size).) Conclusion This study suggest that kicking accuracy is an important factor in achieving success in LGF. This was shown by the results showing what types of kicking are most significant in each half. The results show that teams who perform better in their shooting in the first half are more likely to win the game. Whereas, shooting accuracy is not a significant differentiator in the second half, with kick passing accuracy shown to be significant in order to secure a win . Unsurprisingly, the dominant foot has been shown to perform better, but this reinforces the importance of bilateral skill development as a key component of coaching and session design. This thesis also presents a possible tool for coaches to assess bilateral kicking accuracy. These tools are important potential tools for the LGFA, for the development of the LGF game as well as a tool for individual teams and their coaches

Australian Football Skill-Based Assessments: A Proposed Model for Future Research

Identifying sporting talent remains a difficult task due to the complex nature of sport. Technical skill assessments are used throughout the talent pathway to monitor athletes in an attempt to more effectively predict future performance. These assessments, however, largely focus on the isolated execution of key skills devoid of any game context. When assessments are representative of match-play and applied in a setting where all four components of competition (i.e., technical, tactical, physiological, and psychological) are assessed within an integrated approach, prediction of talent is more likely to be successful. This article explores the current talent identification technical skill assessments, with a particular focus on Australian Football, and proposes a 5-level performance assessment model for athlete assessment. The model separates technical game skill on a continuum from Level-1 (i.e., laboratory analysis) to Level-5 (i.e., match-play). These levels, using the assumptions of the expert performance model and representative learning design theory, incorporate a step-wise progression of performance demands to more closely represent match-play conditions. The proposed model will provide researchers and practitioners with a structured framework to consider when assessing, or developing, new assessments of technical game-based skill

THE EFFECT OF A GAME-SPECIFIC SHORT TERM FATIGUE PROTOCOL ONKICKING IN AUSTRALIAN FOOTBALL

The purpose of this study was to three dimentionally evaluate the effects of a short term game specific fatigue protocol on the kinetics of elite and sub-elite Australian Footballers (AF) during a drop punt kick. Five AF players performed kicks pre and post fatigue protocol. Three dimensional data of the pelvis and kick leg was obtained using a three tower optotrak Certus system (200Hz) and joint torques and moments were calculated in Visual 3D from kick foot toe off until ball contact. Sprint time indicated the protocol induced fatigue. Hip flexion torque significantly increased following fatigue indicating a change in movement strategy similar to that found for jump landing. This greater hip reliant post-fatigue kicking strategy has implications for both skill enhancement and injury prevention

Coordination of place kicking in Rugby Union

Thesis (PhD)--Stellenbosch University, 2020.ENGLISH ABSTRACT: Place kicking is a crucial skill in rugby as more than 40 per cent of the points scored in professional rugby matches are achieved by means of place kicks. Research in rugby kicking has mainly focussed on isolated segment position or movement, with limited literature on segments moving relative to each other. The aim of this study was to identify characteristics of place kicking technique from a coordination and coordination variability perspective. Ten male kickers performed five trials from three different distances (40 m, 32 m, and 22 m) in a range that proficient kickers should convert successfully 80 per cent of the time. An optoelectronic motion capture system consisting of ten cameras were used for capturing total body kinematic data. Data collection took place outdoor, on a rugby field. Data reductions included normalisation of kicking phases, extracting discrete kinematic variables, joint angles, joint and segment coordination patterns (hip-knee, knee-ankle, and pelvis-torso), and coordination variability measures. ANOVA comparisons were made on discrete data, while statistical parametric mapping repeated measures ANOVA analysis was used for continuous variables to determine differences groups differences. Coordination patterns were determined by means of vector coding technique. A bivariate method of calculating the area of the ellipse at each time point was used to determine the coordination variability. A hierarchal cluster analysis was performed on sagittal plane angles at kicking events to determine different technique profiles. Parameters such as greater hip extension and external rotation during the backswing (p=0.001, p=0.015) as well as increased pelvic external rotation (p=0.015) in the 40 m kicks compared to the 22 m and 32 m kicks are related to the formation of the tension arc in attempt to increase foot speed by means of the stretch-shortening cycle. The 40 m kicks had increase knee flexion (p<0.001), increasing the pre-stretch in the thigh muscles. Both factors allow greater force to be applied to kicking foot over greater distance during forward swing. During the forward swing a period of in-phase is reported as both the hip and the knee were flexing, creating a whip-like action. During the backswing the pelvis and thorax worked together to create a tension arc, while during the forward swing, the anti-phase with pelvis dominancy was seen. The pelvis was main mover for tension arc release, while the thorax stays more stable. Even though absolute changes in joint angles were seen, no changes were reported for the coordination patterns when kicking at different distances (22 m, 32 m, 40 m). An investigation into coordination variability found no differences between groups, indicating no change in movement strategy when kicking at different intensities. The cluster analysis revealed three clusters of sagittal plane kinematics describing a knee-dominant, hip-dominant as well as a combination technique. Stemming from the above, place kick training can benefit by coaching cues and drills focussing attention on tension arc formation, and the rhythm of movements. These results impart the knowledge that different distances require similar movement coordination strategies.AFRIKAANSE OPSOMMING: Die stelskop in rugby is ‘n kritiese vaardigheid aangesien meer as 40 persent van die punte aangeteken in ‘n professionele rugbywedstryd te danke aan stelskoppe is. Navorsing in rugby skoppe het meestal geïsoleerde fokus op indivduele segmente, beperkte navoring focks op hoe segmente beweeg relatief tot mekaar. Die doel van die studie was om te eienskappe van stelskoppe te identifiseer vanuit ‘n koördinasie en koördinasie veranderlikheid perspektief. Tien manlike skoppers het elk vyf skoppe vanaf drie verskillende afstande (40 m, 32 m, en 22 m) was vanaf die pale uitgevoer in area waar goeie skoppers 80 persent skopsukses het. Toerusting wat gebruik is vir data-insameling sluit ‘n tien-kamera bewegings analise sisteem in. Data was verwerk deur die normalisering van skop fases, onttrekking van diskrete kinematiese veranderlikes, gewrigshoeke, gewrigskoppelinge (heup-knie, knie-enkel, pelvis-torso), en koördinasie veranderlikheids maatreëls. ANOVA vergelykings is gedoen op die diskrete data, terwyl statistiese parametriese kartering herhaalde metode ANOVA analise uitgevoer is op die kontinue data om beduidende verskille tussen groepe te bepaal. Koppelingshoeke is bepaal deur hoek-hoek plotte en vektorkodering om koördinasie patrone te bepaal. ‘n Tweeverandelike metode is gebruik om die area van die ellips te bereken om die koördinasie variasie te bepaal. ‘n Klusteranaliese was uitgevoer om sagittalevlak skop tegnieke te bepaal. Veranderlikes gekoppel aan spanningsboog formasie, insluitend grooter heup ekstensie en eksterne rotasie gedurende (p=0.001, p=0.015) is verhoog in 40 m skoppe in vergelyking met die 22 m en 32 m skoppe, sowel as meer eksterne rotasie van die pelvis (p=0.015). Die 40 m skoppe het ook verhoogde knie fleksie (p<0.001) getoon in vergelying met die kort afstand skoppe. Beide faktore verhoog krag toegepas oor ‘n groter afstand, op die skopvoet. Koördinasie patrone vir die heup-knie koppeling toon dat die knie die primêre beweger is gedurende die terugswaai. Gedurende die vorentoe swaai kom daar ‘n periode van in-fase voor waartydens die heup en knie albei fleksie ondergaan, wat ‘n sweepslag aksie van die onderste ledemaat tot gelvog het. Gedurende die terugswaai werk die pelvis en toraks saam om ‘n spanningsboog te vorm, terwyl tydens die vorentoe swaai word anti-fase met pelvis dominansie gesien. Die pelvis was dus die primêre beweger vir die vorentoe swaai wat oorseenstem met die vrylating van die spanningsboog, terwyl die toraks meer stabiel bly. Alhoewel absolute verskille gesien is met skoppe vanaf verskillende afstande, bly die koördinasie patrone konstant. ‘n Ondersoek rakende die koördinasie variasie het geen verskille tussen groepe gevind nie wat daarop dui dat daar geen verandering in die bewegings strategie was wanneer geskop word met verskillende intensiteite nie. Dit word vermoed dat die skoppers goed ingeoefende bewegings patrone gehad het vir skoppe vanaf al die afstande. Gebaseer op die bogenoemde resultate, kan navorsingsresultate afrigters help om op spanningsboog, ritmiese koördinasie patrone en die tydsberekening van bewegings te fokus. Die resultate van die studie dui daarop dat geen verandering in bewegings pattrone nodig is nie wanneer daar geskop word met verskillende afstande vanaf die pale.Doctora