Browsing by Author "Tucker, Ross"

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    Correction to: The Use of Sideline Video Review to Facilitate Management Decisions Following Head Trauma in Super Rugby
    (Springer International Publishing, 2018-12-07) Gardner, Andrew J; Kohler, Ryan; McDonald, Warren; Fuller, Gordon W; Tucker, Ross; Makdissi, Michael
    In the original article [1] reference was made to the Hawk-Eye system having been used as the sideline operating system during the 2015 season.
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    Critical analysis of techniques for normalising electromyographic data : from laboratory to clinical research
    (2008) Albertus, Yumna; Lambert, Mike; Derman, Wayne; Tucker, Ross; Noakes, Tim
    Measurements of muscle activity derived from surface EMG electrodes are variable due to both intrinsic and extrinsic factors. The intrinsic factors are endogenous in nature (features within the body) and include muscle fiber type, muscle fiber diameter and length, the amount of tissue between muscle and electrode, and depth and location of muscle with respect to the placement of electrodes (24). These biological factors vary between subjects and cannot be controlled. The extrinsic factors are experimental variables which are influenced by the researcher and can be controlled to some extent. Examples of extrinsic factors include the location, area, orientation, shape of electrodes and the distance between electrodes (interelectrode distance). In order to measure biological variation in the EMG signal, which is important in studies where surface EMG is used to gain understanding of physiological regulation, it is important to minimise the variation caused by these factors. This is in part achieved through the appropriate method of normalisation. The isometric maximal voluntary contraction (MVC) has been used as a standardmethod of normalisation for both static and dynamic exercises. However, researchers have recently improved the methods of normalisation by developing alternative techniques for the measurement of EMG during dynamic activities. By using the same type of movement for normalisation as during the trial, experimental errors can be reduced. The appropriate method of normalisation is defined as a method that is capable of showing repeatability, reliability (low intra-subject variation) and sensitivity to changes in EMG amplitude that is due to biological change and not the contribution of experimental factors. The aim of this thesis was to critically analyse alternative methods of EMG normalisation during dynamic exercise. The data should provide possible guidelines to researchers who are planning studies involving measurement of EMG activity during cycling, running and in clinical populations. Furthermore, the thesis aimed to illustrate that decisions regarding the most appropriate method of normalisation should be based on the study design, research question (absolute muscle activity or changes in muscle pattern) and the muscles being investigated.
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    Diagnostic Utility of New SCAT5 Neurological Screen Sub-tests
    (2021-02-15) Fuller, Gordon W; Miles, John; Tucker, Ross; Douglas, Marc; Raftery, Martin; Falvey, Eanna; Mathema, Prabhat
    Background The Sports Concussion Assessment Tool (SCAT) is recommended to screen for concussion following head impact events in elite sport. The most recent 5th edition (SCAT5) included a ‘rapid neurological screen’ which introduced new subtests examining comprehension, passive neck movement, and diplopia. This study evaluated the additional diagnostic value of these new subtests. Methods A prospective cohort study was performed in the Pro14 elite Rugby Union competition between September 2018 and January 2020. The SCAT5 was administered by the team doctor to players undergoing off-field screening for concussion during a medical room assessment. Sensitivity, specificity, false negatives, and positives were examined for SCAT5 comprehension, passive neck movement, and diplopia subtests. The reference standard was a final diagnosis of concussion, established by serial standardised clinical assessments over 48 h. Results Ninety-three players undergoing off-field screening for concussion were included. Sensitivity and specificity of the comprehension, passive neck movement, and diplopia subtests were 0, 8, 5% and 0, 91, 97%, respectively (concussion prevalence 63%). No players had any abnormality in comprehension. No players had abnormal passive neck movement or diplopia in the absence of abnormalities in other SCAT5 sub-components. Conclusions The new SCAT5 neurological screen subtests are normal in the majority of players undergoing off-field concussion screening and appear to lack diagnostic utility over and above other SCAT5 subtests.
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    Performance and fatigue charateristics of paralympic athletes with cerebral palsy
    (2015) Runciman, Phoebe Anne; Derman, Wayne; Tucker, Ross; Ferreira, Suzanne; Albertus-Kajee, Yumna
    The studies described in this thesis were the first to investigate in - depth body composition, exercise performance and neuromuscular characteristics of elite Paralympic athletes with cerebral palsy (CP). In the first study, in - depth whole body and site specific body composition was investigated in six athletes with CP using dual - energy x - ray absorptiometry. There were no differences between non - affected and affected sides with respect to bone mineral density and fat mass. Fat free soft tissue mass was lower on the affected side in bot h upper and lower limbs of the athletes. The novel findings of this study provided the first insight into anthropometric and bone physiology of elite Paralympic athletes with CP, and the possible residual effect of CP in these individuals. In the second study, five athletes with CP and 16 able - bodied (AB) age and performance matched controls performed a 30 second Wingate sprint cycle test. Power output was significantly higher in the AB group, although fatigue indices were statistically similar between groups. Muscle activity changed similarly in all muscle groups tested, in both affected and non - affected sides, in both CP and AB groups. However, certain neuromuscular irregularities were identified in the CP group. The similarity in fatigue profile was a novel finding. It was proposed that this similarity in fatigue was the result of long term high level athletic training required for Paralympic competition. Study three tested the similarity in fatigue between CP and AB athletes (that was described in the second study), using an externally paced fatiguing running trial. Six athletes with CP and 12 AB athletes performed one 40 m sprint test and vertical jump tests off both legs, the affected leg individually and the non - affected leg individually, before and after an adapted multistage shuttle run test to exhaustion. The 40 m sprint test, vertical jump off both legs and vertical jump off the affected leg were significantly compromised in the CP group, while vertical jump off the non - affected leg was similar between groups. Both groups fatigued similarly with regard to performance and muscle activity. The third study's finding s generally supported those of the second study. However, it was shown that although athletes with CP may represent a group of individuals who have achieved maximal physiological adaptation toward AB levels, the activity generated by both legs was performed towards the capacity of the affected leg. Study four attempted to elucidate explanations for the novel findings in studies 2 and 3 through investigation of pacing strategies employed by these athletes. Six athletes with CP and 13 AB athletes performed two trials of eight sets of ten shuttles (totalling 1600 m). One trial was distance deceived and the other was non distance deceived. The CP group ran slower than the AB group in both trials, and differences in pacing were observed in the deceived trial in the CP group. This novel study provided evidence for a possible pacing strategy underlying the exercise performance and fatigue profiles observed in the athletes with CP documented in the previous studies. The work described in this thesis lends novel insights and understanding to the physiology and physiological adaptations of highly functioning ambulant athletes with CP. The findings might have important implications with respect to the understanding of rehabilitation, coaching and clinical management of individuals with CP.
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    The regulation of exercise performance by a complex anticipatory system
    (2006) Tucker, Ross; Noakes, Tim
    The present thesis examined the hypothesis that self-paced exercise performance and pacing strategies are regulated by a complex intelligent system in advance of a failure to maintain homeostasis in one or more physiological systems. In the first study, ten trained cyclists performed 20 km cycling time-trials in hot (35°C) and cool (15°C) conditions. The power output was reduced in the heat despite core temperatures that were sub-maximal and not different from those measured in the cool condition. Significantly, the reduction in power output was associated with a lower IEMG activity in the active muscle, suggesting that the brain recruited less muscle even at sub-maximal body temperatures. Thus, self-paced exercise in the heat was regulated in advance of thermoregulatory failure. This model was then applied to conditions where the oxygen content of the air was elevated (yperoxia). Eleven subjects performed 20km time-trails, and it was found that a higher power output was maintained throughput hyperoxic (F₁O₂0.21), and that the IEMG activity was elevated in hyperoxia. The subjective rating of perceived exertion (RPE), measured using the Borg scale, was similar in both this and the first study, despite differences in power output. It was suggested that the RPE may play a mediatory role.
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    Revealing complexities within flat-water kayaking: injury prevention and biomechanical analysis
    (2015) Fisher, Julia Marguerite; Tucker, Ross; Karpul, David; Noakes, Timothy
    Elite kayakers are required to perform repetitive movements that create strength and flexibility asymmetries in their bodies, making them susceptible to injury. The first portion of this thesis is dedicated to investigating whether a supervised, corrective pre-habilitation programme of the kinetic chain, conducted twice a week for 10 weeks, would reduce these predisposing factors. A group of 19 marathon paddlers were assessed before and after the intervention, with nine of them receiving the intervention. The 10-week intervention programme was found to significantly improve scapular position and kinesis, thoracic spine extension and single arm pulling ability, thus suggesting improved shoulder function and reduced risk of injury. The second portion of the thesis involved novel biomechanical analysis of kayaking on the water and on a kayaking-ergometer. It is the first objective description of the three dimensional movements of the kayak in the literature. Sprint and marathon paddlers performed a 180 metre time trial using an instrumented paddle with an accelerometer and gyroscope attached to the boat for analysis of boat movement characteristics and paddler-generated forces. Similar patterns for paddle torque, boat acceleration and pitch were observed between male sprint paddlers and male marathon paddlers. However, the direction and timing of the roll and the yaw of the boat during the water phase of the kayak stroke differed between these groups of paddlers. In addition, substantial individual variation existed within the group of male marathon paddlers. On the kayaking ergometer, activation patterns of the trunk and pelvic muscles were measured using electromyography during a maximal 200 metre time trial. Gluteus medius, lower trapezius and erector spinae were measured for the first time in maximal kayaking. The latissimus dorsi, pectoralis major and external oblique muscles were more active during the contralateral phase than has previously been reported. When these paddlers performed a single arm pull test on the same day, the muscle activation patterns changed, and muscle groups were active according to their anatomical function and what has previously been described. First, variation of movement, flexibility and segmental training of the kinetic chain may be advantageous when incorporated with kayaking training to prevent shoulder injury risk factors in paddlers. Second, individual evaluation of three-dimensional boat kinematics and muscle recruitment timing provides objective insight into an individual's kayak technique, with potential benefits for improving technical performance and mechanical efficiency.
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    The science and management of sex verification in sport
    (Health and Medical Publishing Group, 2009) Tucker, Ross; Collins, Malcolm
    The verification of gender eligibility in sporting competition poses a biological and management challenge for sports science and medicine, as well as for sporting authorities. It has been established that in most sporting events, the strength and power advantage possessed by males as a result of the virilising action of hormones such as testosterone produce significant advantages in performance. For this reason, males and females compete largely in separate gender categories. Controversies arise as a result of intersex conditions, where the classification of individuals into male or female is complex. The present review provides the historical context to the debate, identifying the origins of gender verification as a means to deter cheating. It describes how various testing methods have been attempted, including physical examinations of genitalia, molecular techniques including genetic screening, and complex multidisciplinary approaches including endocrinological, genetic and gynaecological examination. To date, none appear to have provided a satisfactory resolution to the problem, and appear instead to have unfairly discriminated against individuals as a result of inappropriate application of testing results. Sporting authorities have formulated position stands for the management of such cases, but there is not absolute agreement between them and little evidence to support whether intersex individuals should or should not be allowed to compete in female categories.
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    The Use of Sideline Video Review to Facilitate Management Decisions Following Head Trauma in Super Rugby
    (Springer International Publishing, 2018-05-24) Gardner, Andrew J; Kohler, Ryan; McDonald, Warren; Fuller, Gordon W; Tucker, Ross; Makdissi, Michael
    Background Sideline video review has been increasingly used to evaluate risk of concussive injury during match play of a number of collision sports, with the view to reducing the incidence of match play concussion injuries. The purpose of this study was to evaluate the effectiveness of sideline video review for identifying and evaluating head impact events in Rugby Union. Methods All Australian teams’ 2015 Super Rugby season matches were studied. Meaningful head impact events (HIEs) were identified, comprising events identified and acted upon during matches and events identified through a post-season retrospective review. Video footage of each HIE was coded by two experienced independent sports medicine clinicians to evaluate management decisions made by match-day (MDD) and team doctors (TD). HIE incidences for matches with and without sideline video were compared, and the agreement between game-day video interpretation and the independent clinician opinion calculated. Results Seventy HIEs were identified in 83 matches (47 identified during matches and 23 identified post-season), equating to 42.5 HIEs per 1000 player match hours. When video review was available, an unnoticed HIE occurred once every 4.3 matches, compared to once every 2.3 matches when the sideline video review was unavailable. Of the 47 identified in-match HIEs evaluated by TD and MDD during the season, 18 resulted in an immediate and permanent removal, 28 resulted in temporary removal for an off-field assessment, and one resulted in the player continuing the game. Game-day head injury assessment process video decisions agreed with the independent clinician view in 72% of cases, κ = 0.49 (95% CI 0.38–0.59, weak agreement). Conclusions These findings suggest that access to sideline video review is an important supplementary component to identify potential concussions; however, there is a critical need for improved systems and processes to reduce the likelihood of missing an incident.
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    Towards an improved understanding of the biomechanical implications and risk of injury of barefoot running
    (2014) Tam, Nicholas; Tucker, Ross; Astephen Wilson, Janie L; Noakes, Tim
    Barefoot running is a subject of significant interest, both in scientific publications and in the lay media as a result of its alleged benefits for runners. These benefits include the potential to reduce injury risk, more economical running and broadly speaking, a better understanding of running biomechanics. Although there are numerous scientific publications describing differences between barefoot and shod running, there is a dearth in understanding whether all runners are able to adapt to the proposed benefits and how this may affect long-term injury risk. Thus, we sought to investigate the biomechanical, neuromuscular and metabolic changes associated with habitually shod runners during the transition to pure barefoot running over an 8- week progressive training programme. This thesis begins with a critical review of the literature, which evaluates the theories and evidence for barefoot running, as well as describing the necessary future research to confirm or refute the barefoot running hypotheses. Our first study aimed to describe acute changes occurring in habitually shod runners when first exposed to barefoot running. We were particularly interested in the variability in response, and whether we could identify factors that predicted potentially favourable changes in kinematic and kinetic outcomes. Fifty-one runners were recruited and assessed using a 3-D motion capture system and integrated force platforms using conventional methods. We found that loading rate was significantly greater in the barefoot condition, but that high individual variability existed, particularly in the barefoot trials. We found that an increase in ankle dorsiflexion is associated with an increase in initial loading rate when in the barefoot condition, supporting previous findings in this regard. We then performed a supervised, pure barefoot running training programme, over 8 weeks, to determine whether the biomechanics of barefoot running would adapt gradually to habituation. Twenty-three runners were recruited for participation, and performed comprehensive biomechanical and neuromuscular assessments before and after the 8-week programme. The first finding was runners do not adapt similarly to barefoot training, and that biomechanics do not change significantly over the 8-week period. High variability in ankle kinematics and loading rate were found, with three sub-groups identified, namely positive responders (reduced loading rate after training), non-responders (no change in loading rate) and negative responders (increase in loading rate after training). We found significant associations between initial loading rate the changes in ankle flexion angle at initial ground contact, presumably as a result of its influence on footstrike. This finding suggests that conscious instruction might be necessary in order to achieve reductions in collision forces during barefoot running. With respect to neuromuscular variables, a persistently higher gastrocnemii muscle preactivation was found in the barefoot condition before and after the training intervention. Increased gastrocnemius pre-activation was associated with lower initial loading rate. An increase in gluteus medius and peroeus longus and a decrease in tibialis anterior pre-activation were also associated with a reduction in initial loading rate after barefoot training. This finding suggests a refined neuromuscular activation strategy prior to ground contact in the barefoot condition to stabilize the hip and centre of mass. Lastly, oxygen cost of transport was found to improve as a result of the barefoot training programme in the male runners and this improvement was found to be associated with a decrease in ground contact time and increase in stride frequency, but no a change in ankle flexion angle at initial ground contact. The outcomes from this thesis elucidate the highly variable response of individuals to barefoot running. This advises individuals choosing to transition to barefoot running to do so with caution. With this in mind, we suggest certain characteristics that may be used as screening mechanisms to indicate individual suitability to barefoot running based on the “collision force theory”. Further, benefits associated with barefoot running other than varied responses in initial loading rate such as improvements in oxygen cost of running are pre-dominantly hypothesised to be a result of musculo-tendinous adaptations, neuromuscular strength and motor control.
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    Understanding risk of injury in novice runners: exploring the link between runner characteristics, biomechanics and injury outcome
    (2020) Coetzee, Devon Ross; Tucker, Ross; Albertus, Yumna; Tam, Nicholas
    The high prevalence of running related injury, particularly in novice runners has prompted the investigation into interventions to mitigate the risk of injury. This dissertation set out to investigate the effects of a progressive 12-week running intervention in novice runners wearing footwear with reduced cushioning. The aim was to understand how intrinsic characteristics of novice runners, namely body composition, strength and flexibility, influence running biomechanics and ultimately injury outcome, and whether footwear structure effects this relationship. Prior to the intervention, participants were assigned to wearing footwear with reduced cushioning (RC) or footwear with traditional cushioning (TC). Three-dimensional running biomechanics were collected during over ground running at 3.0 meters per second in their prescribed footwear. Other measured variables included lower limb strength, by means of an isokinetic dynamometer, lower limb flexibility, full body composition by means of Duel Energy X-Ray Absorptiometry and lower leg bone oedema by means of magnetic resonance imaging. Throughout the intervention, pain or discomfort was assessed. All variables were reassessed after the intervention. The programme used in this thesis resulted in a 11.1 % prevalence of injury, which is considerably lower than other studies. No differences in injury incidence, bone oedema or pain or discomfort prevalence were found between footwear groups, however the RC group experienced pain or discomfort more frequently. Footwear with reduced cushioning was found to promote kinematic strategies, including a lower foot strike angle (FSA), more flexed knee angle at foot strike and reduced knee range of motion during stance phase to compensate for the lack of cushioning. Whilst most novice runners adopted a rear foot strike pattern throughout the intervention, the RC group were four times more likely to reduce FSA. Intrinsic characteristics of novice runners may not be indicative of injury, however the intervention resulted in changes to these variables. These included improvements in movement-specific strength, increased passive hip flexor flexibility and weight loss. Footwear had no effect on these variables. Greater mass characteristics resulted in kinematic adaptations in the knee. This dissertation highlighted the importance of a conservative training structure to mitigate injury risk in novice runners. Additionally, footwear has limited effect on injury risk and thus should not be prescribed to promote biomechanical change, but rather to compliment a runner's current biomechanics and intrinsic characteristics.