ORCID Profile
0000-0003-1234-9579
Current Organisations
Kansas State University
,
Southern Cross University
,
Nnamdi Azikiwe University
,
Edith Cowan University
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Publisher: Informa UK Limited
Date: 2008
DOI: 10.1080/14763140701683155
Abstract: The aim of this study was to quantify the differences between groups of elite canoe slalom athletes based on the class they paddle in and the strategies they use in competition. Canoe and kayak footage was recorded using three cameras and analysed using lapsed-time time-motion analysis. Analysis was undertaken on the ten fastest competition runs for men's kayak and canoes and women's kayak for the 22-gate semi-final/final course at the 2005 canoe slalom world ch ionships. Comparison between the categories of paddlers revealed that despite canoe paddlers taking significantly (P < or = 0.05) fewer strokes than kayak paddlers, they were not significantly slower than men's single kayak paddlers with respect to their run times and only significantly slower between 4 of 22 gates. Results revealed also that paddlers using different turn strategies (spin vs. pivot) had significantly (P < or = 0.05) different split times for the gates before and after the execution of the manoeuvre. For a paddler this means that their in idual strategy could be analysed and compared with those of others to determine if alternate strategies would be beneficial to their performance.
Publisher: SAGE Publications
Date: 18-11-2018
Abstract: Accuracy of a projectile is typically quantified as the proportion of successful target hits, or the distance an object finishes from the target. Serving in sports such as badminton differs since the shuttlecock is usually intercepted by the opponent before landing on the target (i.e. court surface). Therefore, landing accuracy measures are inappropriate and a new method of determining accuracy of the serve is needed. During interviews, elite coaches and players described an accurate short serve as crossing the net with low clearance and having an apex before the net. Three-dimensional trajectory of the shuttlecock was therefore tracked from eight national-level players who performed 30 short serves in simulated match conditions (i.e. with an opponent) 27% of all serves were classified as ‘accurate’, 27% of serves as ‘inaccurate’, 21% with a ‘good apex’ position, and 25% with a ‘good clearance’ height. The proposed method of assessing shuttlecock trajectory as a measure of accuracy could be adopted by coaches and players to assess and improve short serve accuracy. Furthermore, this method is more representative of a match environment since the shuttlecock rarely lands because the opponent returns the serve.
Publisher: Elsevier BV
Date: 2021
Publisher: SAGE Publications
Date: 12-07-2202
Abstract: Women’s international football is growing in terms of popularity, but to date there is limited published research in women’s football and even less that describes effective attacking strategies and the creation of goal scoring opportunities (GSO). The purpose of this research was to investigate and assess the factors related to the creation of GSO that led to a Top 4 position Canada Women’s World Cup 2015. Video footage of each match (n = 52) from the Women’s World Cup (Canada 2015) was analysed using SportsCode Software. The results revealed that the middle third of the pitch was the most effective area for gaining possession and creating GSO. The average time taken to create a GSO was under twelve seconds. The findings of the study can be used by coaches to design training sessions and interventions to successfully create GSO in women’s football. The data from the research may influence the tactical set up of women’s international football teams and help to evolve the game in the same way that research into the men’s game has.
Publisher: Public Library of Science (PLoS)
Date: 23-05-2022
DOI: 10.1371/JOURNAL.PONE.0259034
Abstract: Severe-intensity constant work rate (CWR) cycling tests simulate the high-intensity competition environment and are useful for monitoring training progression and adaptation, yet impose significant physiological and psychological strain, require substantial recovery, and may disrupt athlete training or competition preparation. A brief, minimally fatiguing test providing comparable information is desirable. Purpose To determine whether physiological variables measured during, and functional decline in maximal power output immediately after, a 2-min CWR test can act as a proxy for 4-min test outcomes. Methods Physiological stress ( V ˙ O 2 kinetics, heart rate, blood lactate concentrations ([La - ] b )) was monitored and performance fatigability was estimated (as pre-to-post-CWR changes in 10-s sprint power) during 2- and 4-min CWR tests in 16 high-level cyclists ( V ˙ O 2 peak = 64.4 ± 6.0 ml∙kg -1 ∙min -1 ). The relationship between the 2- and 4-min CWR tests and the physiological variables that best relate to the performance fatigability were investigated. Results The 2-min CWR test evoked a smaller decline in sprint mechanical power (32% vs. 47%, p .001). Both the physiological variables (r = 0.66–0.96) and sprint mechanical power (r = 0.67–0.92) were independently and strongly correlated between 2- and 4-min tests. Differences in V ˙ O 2 peak and [La - ] b in both CWR tests were strongly associated with the decline in sprint mechanical power. Conclusion Strong correlations between 2- and 4-min severe-intensity CWR test outcomes indicated that the shorter test can be used as a proxy for the longer test. A shorter test may be more practical within the elite performance environment due to lower physiological stress and performance fatigability and should have less impact on subsequent training and competition preparation.
Publisher: Informa UK Limited
Date: 18-06-2023
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2010
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2017
Publisher: Hindawi Limited
Date: 11-2018
DOI: 10.1002/TSM2.49
Publisher: Informa UK Limited
Date: 28-06-2012
DOI: 10.1080/15438627.2012.680989
Abstract: Anterior cruciate ligament (ACL) injury rates have increased by ∼50% over the last 10 years. These figures suggest that ACL focused research has not been effective in reducing injury rates among community level athletes. Training protocols designed to reduce ACL injury rates have been both effective (n = 3) and ineffective (n = 7). Although a rationale for the use of exercise to reduce ACL injuries is established, the mechanisms by which they act are relatively unknown. This article provides an injury prevention framework specific to noncontact ACL injuries and the design of prophylactic training protocols. It is also apparent that feedback within this framework is needed to determine how biomechanically relevant risk factors like peak joint loading and muscular support are influenced following training. It is by identifying these links that more effective ACL injury prevention training programs can be developed, and, in turn, lead to reduced ACL injury rates in the future.
Publisher: MDPI AG
Date: 27-12-2022
DOI: 10.3390/NU15010127
Abstract: Objective: Determine if exercise interventions, beyond what is already provided to children and preschool children, improve bone health and reduce fracture incidence. Design: Systematic review and meta-analysis reported using the PRISMA guidelines. Certainty of evidence was assessed using GRADE recommendations. Data sources: Five electronic databases were searched for records: PUBMED CINAHL CENTRAL SPORTDiscus Web of Science. Eligibility criteria for selecting studies: Randomised, quasi-randomised and non-randomised controlled trials (including cluster-randomised) assessing the impact of additional exercise interventions (e.g., increased physical education classes or specific jumping programs) on bone health in children (6–12 years) and pre-school children (2–5 years) without dietary intervention. Results: Thirty-one records representing 16 distinct clinical trials were included. Dual-energy X-ray Absorptiometry (DXA) and/or peripheral Quantitative Computed Tomography (pQCT) were used to quantify bone health. Increased femoral neck bone mineral content in children with additional exercise interventions (n = 790, SMD = 0.55, 95% CI = 0.01 to 1.09) was reported, however this was not significant following sensitivity analysis. Other DXA and pQCT measures, as well as fracture incidence, did not appear to significantly differ over time between intervention and control groups. No studies reported adverse events. Studies failed to report all domains within the TIDieR checklist. All studies were at high risk of bias using the Cochrane RoB Tool 2.0. The certainty of the evidence was very low. Conclusions: The addition of exercise interventions, beyond what is provided to children, does not appear to improve DXA and pQCT measures of bone health. The effect of additional exercise interventions on bone health in pre-school children is largely unknown. Future trials should ensure adherence is clearly reported and controlled for within analysis as well as including reports of adverse events (e.g., apophysitis) that occur due to increased exercise interventions.
Publisher: SAGE Publications
Date: 29-03-2020
Abstract: The ability to accurately project (e.g. throw, kick, hit) an object at high speed is a uniquely human skill, and this ability has become a critical feature of many competitive sports. Nonetheless, in some sports, the target or end-point for a projected object is often not reached because an opponent intercepts or returns the object thus, a player cannot use object landing location information to inform accuracy outcome. By comparing the landing location of serves performed without an opponent by elite badminton players to predicted landing points of serves delivered with an opponent, we aimed to determine whether object projection accuracy is affected by the presence of an opponent. Landing locations of serves to an opponent were predicted using a model developed through analysis of serves without an opponent present. The model predicted that 69% of serves to an opponent would have landed on or short (i.e. outside the permitted area) of the service line. Thus, serve trajectory in elite badminton players was considerably altered by the presence of an opponent, despite their aim to serve to a specific point on the court.
Publisher: Informa UK Limited
Date: 21-03-2020
Publisher: Informa UK Limited
Date: 02-01-2016
DOI: 10.1080/14763141.2015.1123764
Abstract: It is unknown whether skilled golfers will modify their kinematics when using drivers of different shaft properties. This study aimed to firstly determine if golf swing kinematics and swing parameters and related launch conditions differed when using modified drivers, then secondly, determine which kinematics were associated with clubhead speed. Twenty high level amateur male golfers (M ± SD: handicap = 1.9 ± 1.9 score) had their three-dimensional (3D) trunk and wrist kinematics collected for two driver trials. Swing parameters and related launch conditions were collected using a launch monitor. A one-way repeated measures ANOVA revealed significant (p ≤ 0.003) between driver differences specifically, faster trunk axial rotation velocity and an early wrist release for the low kick point driver. Launch angle was shown to be 2° lower for the high kick point driver. Regression models for both drivers explained a significant amount of variance (60-67%) in clubhead speed. Wrist kinematics were most associated with clubhead speed, indicating the importance of the wrists in producing clubhead speed regardless of driver shaft properties.
Publisher: Cold Spring Harbor Laboratory
Date: 18-10-2021
DOI: 10.1101/2021.10.17.464459
Abstract: The ability to shift from walking and jogging to sprinting gaits, even when fatigued after prolonged effort, would have been as useful to our hunter-gatherer ancestors as it is to modern athletes. During prolonged jogging, joint moment and work decrease in the distal (ankle) joint but increase at proximal (hip/knee) joints as fatigue progresses, and such adaptations might be expected to occur in sprinting. Fatigue is also thought to increase inter-limb kinematic and force production asymmetries, which are speculated to influence injury risk. However, the effects of running-related fatigue on sprint running gait have been incompletely studied, so these hypotheses remain untested. We studied 3-D kinematics and ground reaction force production in dominant (DL) and non-dominant (NDL) legs during both non-fatigued and fatigued sprinting in habitual but uncoached running athletes. Contrary to the tested hypotheses, relative between-leg differences were greater in non-fatigued than fatigued sprinting. When not fatigued, DL produced greater propulsive impulse through both greater positive and negative work being done at the ankle, whilst NDL produced more vertical impulse, possibly resulting from the greater hip flexion observed prior to the downwards acceleration of the foot towards the ground. Whilst few changes were detected in DL once fatigued, NDL shifted towards greater horizontal force production, largely resulting from an increase in plantarflexion (distal-joint) moments and power. After fatiguing running, therefore, inter-limb asymmetry was reduced during sprinting and no distal-to-proximal shift in work ower was detected. Speculatively, these adaptations may help to attenuate decreases in running speed whilst minimising injury risk. The ability to attain fast running speeds may critically determine success in tasks such as prey chase- and-capture in hunter-gatherer societies as well as success in modern sports competitions. At times, sprint running may have to be performed whilst fatigued from previous, longer-distance running, when speeds are reduced, and injury risk may be higher. Previous work indicated that fatigue prompts a proximal shift in joint work and power production and an increase in inter-limb asymmetry. On the contrary, we show that relative ankle positive and negative joint work was maintained in the face of fatigue and that inter-limb asymmetry was reduced in a group of runners experienced, but not formally instructed, in both long-distance and sprint running.
Publisher: The Royal Society
Date: 08-2020
DOI: 10.1098/RSOS.192093
Abstract: Detailed examinations of both the movement and muscle activation patterns used by animals and humans to complete complex tasks are difficult to obtain in many environments. Therefore, the ability to infer movement and muscle activation patterns after capture of a single set of easily obtained data is highly sought after. One possible solution to this problem is to capture force-time data through the use of appropriate transducers, then interrogate the signal's derivative, the yank-time signal, which lifies, and thus highlights, temporal force-time changes. Because the countermovement vertical jump (CMJ) is a complex movement that has been well studied in humans, it provides an excellent preliminary model to test the validity of this solution. The aim of the present study was therefore to explore the use of yank-time signal, derived from vertical ground reaction force-time data, to identify and describe important kinematic (captured using three-dimensional motion analysis) and kinetic events in the CMJ, and to relate these to possible muscle activation (electromyography) events that underpin them. It was found that the yank-time signal could be used to accurately identify several key events during the CMJ that are likely to be missed or misidentified when only force-time data are inspected, including the first instances of joint flexion and centre of mass movement. Four different jump profiles (i.e. kinematic patterns) were inferred from the yank-time data, which were linked to different patterns of muscle activation. Therefore, yank-time signal interrogation provides a viable method of estimating kinematic patterns and muscle activation strategies in complex human movements.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2013
Publisher: SAGE Publications
Date: 19-10-2022
DOI: 10.1177/02646196221131741
Abstract: Australian children with visual impairment (VI) are underrepresented in studies exploring engagement in physical activities. Existing research documents that children with VI do not meet recommendations for physical activity guidelines which negatively impacts their physical and mental health. To improve participation, information is needed on what physical activities children with VI participate in and why. The objective of this study was to explore what physical activities children with VI participate in and why how they first got involved in them. A larger study was designed to explore multiple aspects of physical activity participation. This article presents findings relevant to what activities Western Australian children with VI participate in and factors which initiated participation. Findings were collected through a survey returned by 38 families and interviews with 22 families including parents and children with VI. School physical education, swimming, play equipment, and walking were the activities with the highest number of participants. Parent factors which motivated participation were having strong values/beliefs which supported engagement, modelling participation in activities, and seeking specific benefits/outcomes. Child factors which motivated participation included impact of their VI and the child’s choice/interest. External factors included advertisements and accessibility of information. Many Australian children with VI and their parents are motivated to engage in physical activities, with initial participation commonly catalysed by external factors.
Publisher: Informa UK Limited
Date: 06-2013
DOI: 10.1080/14763141.2012.728244
Abstract: The aims of this study were (i) to determine whether significant three-dimensional (3D) trunk kinematic differences existed between a driver and a five-iron during a golf swing and (ii) to determine the anthropometric, physiological, and trunk kinematic variables associated with clubhead speed. Trunk range of motion and golf swing kinematic data were collected from 15 low-handicap male golfers (handicap = 2.5 +/- 1.9). Data were collected using a 10-camera motion capture system operating at 250 Hz. Data on clubhead speed and ball velocity were collected using a real-time launch monitor. Paired t-tests revealed nine significant (p < or = 0.0019) between-club differences for golf swing kinematics, namely trunk and lower trunk flexion/extension and lower trunk axial rotation. Multiple regression analyses explained 33.7-66.7% of the variance in clubhead speed for the driver and five-iron, respectively, with both trunk and lower trunk variables showing associations with clubhead speed. Future studies should consider the role of the upper limbs and modifiable features of the golf club in developing clubhead speed for the driver in particular.
Publisher: Informa UK Limited
Date: 11-2013
DOI: 10.1080/02640414.2013.793377
Abstract: Athletic profiling provides valuable information to sport scientists, assisting in the optimal design of strength and conditioning programmes. Understanding the influence these physical characteristics may have on the generation of kicking accuracy is advantageous. The aim of this study was to profile and compare the lower limb mass characteristics of accurate and inaccurate Australian footballers. Thirty-one players were recruited from the Western Australian Football League to perform ten drop punt kicks over 20 metres to a player target. Players were separated into accurate (n = 15) and inaccurate (n = 16) groups, with leg mass characteristics assessed using whole body dual energy x-ray absorptiometry (DXA) scans. Accurate kickers demonstrated significantly greater relative lean mass (P ≤ 0.004) and significantly lower relative fat mass (P ≤ 0.024) across all segments of the kicking and support limbs, while also exhibiting significantly higher intra-limb lean-to-fat mass ratios for all segments across both limbs (P ≤ 0.009). Inaccurate kickers also produced significantly larger asymmetries between limbs than accurate kickers (P ≤ 0.028), showing considerably lower lean mass in their support leg. These results illustrate a difference in leg mass characteristics between accurate and inaccurate kickers, highlighting the potential influence these may have on technical proficiency of the drop punt.
Publisher: Springer Science and Business Media LLC
Date: 30-11-2013
DOI: 10.1007/S40279-013-0131-0
Abstract: A high level of participant skill is influential in determining the outcome of many sports. Thus, tests assessing skill outcomes in sport are commonly used by coaches and researchers to estimate an athlete's ability level, to evaluate the effectiveness of interventions or for the purpose of talent identification. The objective of this systematic review was to examine the methodological quality, measurement properties and feasibility characteristics of sporting skill outcome tests reported in the peer-reviewed literature. A search of both SPORTDiscus and MEDLINE databases was undertaken. Studies that examined tests of sporting skill outcomes were reviewed. Only studies that investigated measurement properties of the test (reliability or validity) were included. A total of 22 studies met the inclusion/exclusion criteria. A customised checklist of assessment criteria, based on previous research, was utilised for the purpose of this review. A range of sports were the subject of the 22 studies included in this review, with considerations relating to methodological quality being generally well addressed by authors. A range of methods and statistical procedures were used by researchers to determine the measurement properties of their skill outcome tests. The majority (95%) of the reviewed studies investigated test-retest reliability, and where relevant, inter and intra-rater reliability was also determined. Content validity was examined in 68% of the studies, with most tests investigating multiple skill domains relevant to the sport. Only 18% of studies assessed all three reviewed forms of validity (content, construct and criterion), with just 14% investigating the predictive validity of the test. Test responsiveness was reported in only 9% of studies, whilst feasibility received varying levels of attention. In organised sport, further tests may exist which have not been investigated in this review. This could be due to such tests firstly not being published in the peer-review literature and secondly, not having their measurement properties (i.e., reliability or validity) examined formally. Of the 22 studies included in this review, items relating to test methodological quality were, on the whole, well addressed. Test-retest reliability was determined in all but one of the reviewed studies, whilst most studies investigated at least two aspects of validity (i.e., content, construct or criterion-related validity). Few studies examined predictive validity or responsiveness. While feasibility was addressed in over half of the studies, practicality and test limitations were rarely addressed. Consideration of study quality, measurement properties and feasibility components assessed in this review can assist future researchers when developing or modifying tests of sporting skill outcomes.
Publisher: Springer Science and Business Media LLC
Date: 10-02-2023
DOI: 10.1007/S00421-023-05148-W
Abstract: To understand muscle damage in badminton, changes in neuromuscular function were investigated after simulated badminton singles matches performed by ten state-level male players. Each participant played eight matches and measurements were taken before, immediately after, and 1 and 24 h after each match. Maximal voluntary isometric contraction (MVC) torque of the knee extensors and flexors, voluntary activation (VA) during MVC and torques generated by doublet ( T Doublet ), 20 ( T 20 ) and 80 Hz ( T 80 ) electrical stimulations of the knee extensors were measured from the dominant leg (the racket-hold arm side). Muscle soreness was assessed by a 100-mm visual analogue scale from both legs. The number of lunges performed by each participant in each match was analysed by videos, and its relations to other measures were examined. Pre-match knee extensor and flexor MVC torques were 278.4 ± 50.8 Nm and 143.0 ± 36.2 Nm, respectively. Knee extensor MVC torque of the dominant leg decreased immediately (12.0 ± 2.9%) and 1 h post-match (16.0 ± 3.2%), but returned to baseline at 24 h post-match. VA (11.4 ± 2.9%), T Doublet (13.1 ± 6.0%), T 20 (31.1 ± 12.3%) and T 80 (25.5 ± 7.9%) decreased ( p 0.01) immediately post-match but recovered by 24 h post-match. A significant correlation ( r = − 0.64, p 0.01) was observed between the total number of lunges performed in a match (160–240 times) and the magnitude of decrease in MVC torque (6.4–14.7%). Muscle soreness developed more ( p 0.05) for the dominant (51.5 ± 11.6 mm) than the non-dominant leg (18.8 ± 8.6 mm). Muscle damage induced by singles badminton matches was minimal, but the more the lunges are performed, the greater the neuromuscular fatigue.
Publisher: Informa UK Limited
Date: 05-2007
DOI: 10.1080/14763140701324842
Abstract: The aim of this study was to assess intra-observer and inter-observer reliability of data gathered from a lapsed-time time-motion analysis of canoe slalom competition. The data were collected using a definition set developed in conjunction with elite canoe slalom coaches. Competition runs from four national-standard paddlers in a national selection race were analysed in random order three times by three observers. For each run, observers identified various events specific to canoe slalom, including time taken between gates, touched and missed gates, turn times, major and minor avoidance, rolls, paddle in and out of water times, and stroke classification. The error of measurement was determined for each of these variables. For time taken between gates and turn times, the error was < or = 0.21 and < or = 0.39 s for intra-observer and inter-observer analysis, respectively. The error for stroke in and out of water times was < or = 0.08 and < or = 0.13 s for intra-observer and inter-observer analysis, respectively. Analysis of stroke classification identification for intra-observer comparisons revealed that 91% of the time identical stroke identification occurred. Inter-observer analysis revealed identical stroke identification was achieved 81% of the time. These reliability data compare favourably with previous time-motion analysis in other sports using fewer variables.
Publisher: Informa UK Limited
Date: 02-05-2022
Publisher: Informa UK Limited
Date: 04-10-2018
DOI: 10.1080/14763141.2018.1512149
Abstract: Push-ups represent one of the simplest and most popular strengthening exercise. The aim of this study was to systematically review and critically appraise the literature on the kinetics-related characteristics of different types of push-ups, with the objective of optimising training prescription and exercise-related load. A systematic search was conducted in the electronic databases PubMed, Google Scholar and Science Direct up to April 2018. Studies that reported kinetic data (e.g. initial and peak-force supported by the upper-limbs, impact-force, peak-flexion-moment of the elbow-joint, rate of propulsive- and impact-, and vertebral-joint compressive-forces) related to push-ups and included trained, recreational and untrained participants, were considered. The risk of bias in the included studies was assessed using the Critical Appraisal Skills Programme scale. From 5290 articles retrieved in the initial search, only 26 studies were included in this review. Kinetic data for 46 push-up variants were assessed. A limitation of the current review is that the relationship between our findings and actual clinical or practical consequences is not statistically proven but can only be inferred from our critical descriptive approach. Overall, this review provides detailed data on specific characteristics and intensities of push-up variations, in order to optimise exercise prescription for training and rehabilitation purposes.
Publisher: Wiley
Date: 29-01-2023
DOI: 10.1111/SMS.14318
Abstract: During initial acceleration, the first steps of a maximal‐effort (sprint) run often determine success or failure in the capture and evasion of an opponent, and is therefore a vital factor of success in many modern sports. However, accelerative events are commonly performed after having already run considerable distances, and the associated fatigue should impair muscle force production and thus reduce acceleration. Despite this, the effects of running‐induced fatigue on our ability to accelerate as well as the running technique used to achieve it have received little attention. We recorded 3‐D kinematics and ground reaction forces during the first three steps of the acceleration phase from a standing start before and after performing a high‐speed, multi‐directional, fatiguing run‐walk protocol in well‐trained running athletes who were habituated to accelerative sprinting. We found that the athletes were able to maintain their acceleration despite changing running technique, which was associated with use of a more upright posture, longer ground contact time, increased vertical ground reaction impulse, decreased hip flexion and extension velocities, and a shift in peak joint moments, power, and positive work from the hip to the knee joint no changes were detected in ankle joint function. Thus, a compensatory increase in knee joint function alleviated the reduction in hip flexor‐extensor capacity. These acute adaptations may indicate that the hip extensors (gluteal and hamstring muscle groups) were more susceptible to fatigue than the ankle and knee musculature, and may thus be a primary target for interventions promoting fatigue resistance.
Publisher: Wiley
Date: 25-01-2013
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.JBIOMECH.2019.05.036
Abstract: During range of motion (max-ROM) tests performed on an isokinetic dynamometer, the mechanical delay between the button press (by the participant to signal their max-ROM) and the stopping of joint rotation resulting from system inertia induces errors in both max-ROM and maximum passive joint moment. The present study aimed to quantify these errors by comparing data when max-ROM was obtained from the joint position data, as usual (max-ROM
Publisher: Cold Spring Harbor Laboratory
Date: 22-04-2022
DOI: 10.1101/2022.04.21.489102
Abstract: The rate of initial acceleration during the first steps of a maximal-effort (sprint) run often determines success or failure in prey capture and predator evasion, and is a vital factor of success in many modern sports. However, accelerative events are commonly performed after having already run considerable distances, and the associated fatigue should impair muscle force production and thus reduce acceleration rate. Despite this, the effects of running-induced fatigue on our ability to accelerate as well as the running technique used to achieve it has been incompletely studied. We recorded 3-D kinematics and ground reaction forces during the first three steps of the acceleration phase from a standing start before and after performing a high-speed, multi-directional, fatiguing run-walk protocol in well-trained running athletes who were habituated to accelerative sprinting. We found that the athletes were able to maintain their rate of initial acceleration despite changing running technique, which was associated with use of a more upright posture, longer ground contact time, increased vertical ground reaction impulse, decreased hip flexion and extension velocities, and a shift in peak joint moments, power, and positive work from the hip to the knee joint no changes were detected in ankle joint function. Thus, a compensatory increase in knee joint function alleviated the reduction in hip flexor-extensor capacity. These acute adaptations may indicate that the hip extensors (gluteal and hamstring muscle groups) were more susceptible to fatigue than the ankle and knee musculature, and may thus be a primary target for interventions promoting fatigue resistance.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 14-02-2020
DOI: 10.1519/JSC.0000000000003458
Abstract: Jacob, Y, Hart, NH, Cochrane, JL, Spiteri, T, Laws, SM, Jones, A, Rogalski, B, Kenna, J, and Anderton, RS. ACTN3 (R577X) genotype is associated with Australian Football League players. J Strength Cond Res 36(2): 573–576, 2022—Genetic variants in the angiotensin-converting enzyme ( ACE ) and alpha actinin-3 ( ACTN3 ) genes have been associated with elite sport athletic performance. This study aimed to investigate the frequency of each polymorphism in a cohort of elite Australian football (AF) players. To achieve this, 47 players from an Australian Football League (AFL) club and 59 healthy age matched controls with no history of elite sporting competition were recruited for this study. Each subject provided saliva s les through buccal swab for DNA extraction and genotyping, with group comparisons made using χ 2 and odds ratio analysis. There was no significant difference in ACE I/D genotype between healthy control and elite AF players. The ACTN3 XX genotype was significantly underrepresented in AFL players (4.3%) compared with healthy controls (28.8%, p = 0.003). In addition, there was a greater representation of the R allele in elite AF players (70.2%) when compared with healthy controls (50% χ 2 = 8.834, p = 0.002). This is the first study to investigate genetic variants in elite AF players, with results suggesting that the ACTN3 gene may play a significant role explaining aspects of athletic performance in AF.
Publisher: Cold Spring Harbor Laboratory
Date: 12-10-2021
DOI: 10.1101/2021.10.12.464126
Abstract: Severe-intensity constant work rate (CWR) cycling tests are useful for monitoring training progression and adaptation as they impose significant physiological and psychological strain and thus simulate the high-intensity competition environment. However, fatiguing tests require substantial recovery and may disrupt athlete training or competition preparation. Therefore, the development of a brief, minimally fatiguing test providing comparable information is desirable. To determine whether physiological variables measured during, and functional decline in maximal power output immediately after, a 2-min CWR test can act as a proxy for 4-min test outcomes. Physiological stress was monitored and pre-to-post-CWR changes in 10-s sprint power computed (to estimate performance fatigability) during 2- and 4-min CWR tests in high-level cyclists. The 2-min CWR test evoked a smaller decline in sprint mechanical power (32% vs. 47%, p .001), however both the physiological variables and sprint mechanical power were independently and strongly correlated between 2- and 4-min tests. Differences in V · O 2peak and blood lactate concentration in both CWR tests were strongly associated with the decline in sprint mechanical power. Physiological variables measured during, and the loss in sprint mechanical power measured after, a severe-intensity 2-min CWR test were less than in the 4-min test. Yet strong correlations between 2- and 4-min test outcomes indicated that the 2-min test can be used as a proxy for the longer test. Because shorter tests are less strenuous, they should have less impact on training and competition preparation and may therefore be more practically applicable within the elite performance environment.
Publisher: MDPI AG
Date: 29-01-2021
Abstract: Genetic variants in the angiotensin-converting enzyme (ACE) (rs4343), alpha-actinin-3 (ACTN3) (rs1815739), adrenoceptor-beta-1 (ADRB1) (rs1801253), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) (rs8192678) genes have previously been associated with elite athletic performance. This study assessed the influence of polymorphisms in these candidate genes towards endurance test performance in 46 players from a single Australian Football League (AFL) team. Each player provided saliva buccal swab s les for DNA analysis and genotyping and were required to perform two independent two-kilometre running time-trials, six weeks apart. Linear mixed models were created to account for repeated measures over time and to determine whether player genotypes are associated with overall performance in the two-kilometre time-trial. The results showed that the ADRB1 Arg389Gly CC (p = 0.034) and PPARGC1A Gly482Ser GG (p = 0.031) genotypes were significantly associated with a faster two-kilometre time-trial. This is the first study to link genetic polymorphism to an assessment of endurance performance in Australian Football and provides justification for further exploratory or confirmatory studies.
Publisher: Human Kinetics
Date: 02-2017
Abstract: To examine differences between ground-reaction-force (GRF)-based parameters collected from 5 types of plyometric push-ups. Between-trials reliability and the relationships between parameters were also assessed. Thirty-seven highly active commando soldiers performed 3 trials of 5 variations of the plyometric push-up in a counterbalanced order: standard countermovement push-up (SCPu), standard squat push-up (SSPu), kneeling countermovement push-up (KCPu), kneeling squat push-up (KSPu), and drop-fall push-up (DFPu). Vertical GRF was measured during these exercises using a portable Kistler force plate. The GRF applied by the hands in the starting position (initial force supported), peak GRF and rate of force development during takeoff, flight time, impact force, and rate of force development impact on landing were determined. During standard-position exercises (SCPu and SSPu) the initial force supported and impact force were higher ( P .001) than with kneeling exercises (KCPu, KSPu, and DFPu). The peak GRF and rate of force development during takeoff were higher ( P .001) in the countermovement push-up exercises ([CMP] SCPu, KCPu, and DFPu) than squat push-up exercises ([SP] SSPu and KSPu). Furthermore, the flight time was greater ( P .001) during kneeling exercises than during standard-position exercises. A significant relationship ( P .01) between impact force and the rate of force development impact was observed for CMP and SP exercises ( r = .83 and r = .62, respectively). The initial force supported was also negatively related ( P .01) to the flight time for both CMP and SP ( r = –.74 and r = –.80, respectively). It was revealed that the initial force supported and the peak GRF during takeoff had excellent reliability however, other parameters had poor absolute reliability. It is possible to adjust the intensity of plyometric push-up exercises and train athletes’ muscle power by correctly interpreting GRF-based parameters. However, caution is required as some parameters had marginal absolute reliability.
Publisher: Springer Science and Business Media LLC
Date: 11-10-2022
DOI: 10.1186/S40798-022-00522-Y
Abstract: Australian Football is a dynamic team sport that requires many athletic traits to succeed. Due to this combination of traits, as well as technical skill and physicality, there are many types of injuries that could occur. Injuries are not only a hindrance to the in idual player, but to the team as a whole. Many strength and conditioning personnel strive to minimise injuries to players to accomplish team success. To investigate whether selected polymorphisms have an association with injury occurrence in elite male Australian Football players. Using DNA obtained from 46 elite male players, we investigated the associations of injury-related polymorphisms across multiple genes ( ACTN3, CCL2, COL1A1, COL5A1, COL12A1, EMILIN1, IGF2, NOGGIN, SMAD6 ) with injury incidence, severity, type (contact and non-contact), and tissue (muscle, bone, tendon, ligament) over 7 years in one Australian Football League team. A significant association was observed between the rs1372857 variant in NOGGIN ( p = 0.023) and the number of total muscle injuries, with carriers of the GG genotype having a higher estimated number of injuries, and moderate, or combined moderate and high severity rated total muscle injuries. The COL5A1 rs12722TT genotype also had a significant association ( p = 0.028) with the number of total muscle injuries. The COL5A1 variant also had a significant association with contact bone injuries ( p = 0.030), with a significant association being found with moderate rated injuries. The IGF2 rs3213221-CC variant was significantly associated with a higher estimated number of contact tendon injuries per game ( p = 0.028), while a higher estimated number of total ligament ( p = 0.019) and non-contact ligament ( p = 0.002 ) injuries per game were significantly associated with carriage of the COL1A1 rs1800012-TT genotype. Our preliminary study is the first to examine associations between genetic variants and injury in Australian Football. NOGGIN rs1372857-GG, COL5A1 rs12722-TT, IGF2 rs3213221-CC, and COL1A1 rs1800012-TT genotypes held various associations with muscle-, bone-, tendon- and ligament-related injuries of differing severities. To further increase our understanding of these, and other, genetic variant associations with injury, competition-wide AFL studies that use more players and a larger array of gene candidates is essential.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2001
DOI: 10.1097/00005768-200107000-00014
Abstract: To investigate the external loads applied to the knee joint during dynamic cutting tasks and assess the potential for ligament loading. A 50-Hz VICON motion analysis system was used to determine the lower limb kinematics of 11 healthy male subjects during running, sidestepping, and crossover cut. A kinematic model was used in conjunction with force place data to calculate the three-dimensional loads at the knee joint during stance phase. External flexion/extension loads at the knee joint were similar across tasks however, the varus/valgus and internal/external rotation moments applied to the knee during sidestepping and crossover cutting were considerably larger than those measured during normal running (P < 0.05). Sidestepping tasks elicited combined loads of flexion, valgus, and internal rotation, whereas crossover cutting tasks elicited combined loads of flexion, varus, and external rotation. Compared with running, the potential for increased ligament loading during sidestepping and crossover cutting maneuvers is a result of the large increase in varus/valgus and internal/external rotation moments rather than any change in the external flexion moment. The combined external moments applied to the knee joint during stance phase of the cutting tasks are believed to place the ACL and collateral ligaments at risk of injury, particularly at knee flexion angles between 0 degrees and 40 degrees, if appropriate muscle activation strategies are not used to counter these moments.
Publisher: Japan Society of Physical Education, Health, and Sport Sciences
Date: 2005
DOI: 10.5432/IJSHS.3.272
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2001
DOI: 10.1097/00005768-200107000-00015
Abstract: To determine how unanticipated performance of cutting maneuvers in sport affects the external loads applied to the knee joint and the potential risk for ligament injury. A 50-Hz VICON motion analysis system was used to determine the lower limb kinematics of 11 healthy male subjects during running and cutting tasks performed under preplanned (PP) and unanticipated (UN) conditions. Subjects performed the UN tasks in response to a light stimulus on a target board. A kinematic model was then used in conjunction with force place data to calculate the three-dimensional loads at the knee joint. External flexion/extension moments at the knee joint were similar between PP and UN conditions however, the varus/valgus and internal/external rotation moments during the UN cutting tasks were up to twice the magnitude of the moments measured during the PP condition. Cutting maneuvers performed without adequate planning may increase the risk of noncontact knee ligament injury due to the increased external varus/valgus and internal/external rotation moments applied to the knee. These results are probably due to the small amount of time to make appropriate postural adjustments before performance of the task, such as the position of the foot on the ground relative to the body center of mass. Subsequently, training for the game situation should involve drills that familiarize players with making unanticipated changes of direction. Practice sessions should also incorporate plyometrics and should focus on better interpretation of visual cues to increase the time available to preplan a movement.
Publisher: Springer Science and Business Media LLC
Date: 21-09-2021
DOI: 10.1007/S11356-021-16556-W
Abstract: It is important that a pollution remediation system be able to cater for a variety of pollutant species present in the water to be treated. The aim of this study was to utilise a series of commercial zeolites (H-MOR, H-β, and H-ZSM5) for the concomitant adsorption and photodegradation of Cu
Publisher: Elsevier BV
Date: 04-2007
DOI: 10.1016/J.JSAMS.2006.05.015
Abstract: Anterior cruciate ligament (ACL) injuries are the most costly injuries in football at both professional and amateur levels (Orchard J, Seward H, McGivern J, Hood S. Intrinsic and extrinsic risk factors for anterior cruciate ligament injury in Australian footballers. Am J Sports Med 2001 :196-200.). In this study video analysis of 34 ACL injuries in Australian football was performed to investigate the causes of these injuries. Factors that may have contributed to the cause of the injury were analysed, rated and reported. The factors analysed were: type of manoeuvre, direction the knee 'gave way', running speed, knee angle, cutting angle and if the player was accelerating or decelerating. The majority of the injuries analysed occurred in non-contact situations (56%). Of these 37% occurred during sidestepping manoeuvres, 32% in landing, 16% land and step, 10% stopping/slowing and 5% crossover cut manoeuvres. Ninety-two percent of the non-contact injuries occurred at extended knee angles of 30 degrees or less, which is also commonly known to place stress on the ACL and reduce the protective role of hamstrings. Over half (54%) of non-contact injuries occurred whilst decelerating. It would be expected that greater speed and angle cut too would increase the frequency of ACL injury. The results could not confirm this with most injuries occurring at running speeds of slow jogging to running and equal number of injuries occurred at cutting to angles of the ranges 15-45 degrees and 45-75 degrees. These results give greater understanding into potential causes or contributors of ACL injury and information to assist in the development of knee injury prevention programs.
Publisher: Informa UK Limited
Date: 11-2013
DOI: 10.1080/17461391.2013.774053
Abstract: Understanding the magnitude of forces and lower body kinematics that occur during a change of direction (COD) task can provide information about the biomechanical demands required to improve performance. To compare the magnitude of force, impulse, lower body kinematics and post-COD stride velocity produced between athletes of different strength levels during a COD task, 12 stronger (8 males, 4 females) and 12 weaker (4 males, 8 females) recreational team sport athletes were recruited. Strength levels were determined by relative peak isometric force of the dominant and non-dominant leg. All athletes performed 10 pre-planned 45° changes of direction (5 left, 5 right) while three-dimensional motion and ground reaction force (GRF) data were collected. Differences in all variables for the dominant leg were examined using a one-way analysis of variance (ANOVA) with a level of significance set at p ≤0.05. The stronger group displayed significantly faster post-COD stride velocity and greater vertical and horizontal braking forces, vertical propulsive force, vertical braking impulse, horizontal propulsive impulse, angle of peak braking force application, hip abduction and knee flexion angle compared to the weaker group. The results suggest that in iduals with greater relative lower body strength produced higher magnitude plant foot kinetics and modified lower body positioning while producing faster COD performances. Future investigations should determine if strength training to enable athletes to increase plant foot kinetics while maintaining or adopting a lower body position results in a concomitant increases in post-COD stride velocity.
No related grants have been discovered for Jodie Cochrane Wilkie.