ORCID Profile
0000-0001-8219-6120
Current Organisation
Murdoch University
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Publisher: Springer Science and Business Media LLC
Date: 24-09-2012
DOI: 10.1007/S00167-011-1681-Z
Abstract: To examine articular cartilage and subchondral bone changes in tibiofemoral and patellofemoral joints following partial medial meniscectomy. For this cross-sectional study, 158 patients aged 30-55 years, without evidence of knee osteoarthritis at arthroscopic partial medial meniscectomy (APMM), and 38 controls were recruited. MRI was performed once on the operated knee for each subcohort of 3 months, 2 or 4 years post-surgery, and the randomly assigned knee of the controls. Cartilage volume, cartilage defects, and bone size were assessed using validated methods. Compared with controls, APMM patients had more prevalent cartilage defects in medial tibiofemoral (OR = 3.17, 95%CI 1.24-8.11) and patellofemoral (OR = 13.76, 95%CI 1.52-124.80) compartments, and increased medial tibial plateau bone area (B = 143.8, 95%CI 57.4-230.2). Time from APMM was positively associated with cartilage defect prevalence in medial tibiofemoral (OR = 1.02, 95%CI 1.00-1.03) and patellofemoral (OR = 1.04, 95%CI 1.01-1.07) compartments, and medial tibial plateau area (B = 2.5, 95%CI 0.8-4.3), but negatively associated with lateral tibial cartilage volume (B = -4.9, 95%CI -8.4 to -1.5). The association of APMM and time from APMM with patellar cartilage defects was independent of tibial cartilage volume. Partial medial meniscectomy is associated with adverse effects on articular cartilage and subchondral bone, which are associated with subsequent osteoarthritis, in both tibiofemoral and patellofemoral compartments. III.
Publisher: Georg Thieme Verlag KG
Date: 02-2018
Abstract: Objective This article aims to investigate the effect of a decrease in the A-frame angle of incline on the highest carpal extension angle in agility dogs. Methods Kinematic gait analysis (two-dimensional) measuring carpal extension was performed on 40 dogs entering the A-frame at 3 angles of incline: 40° (standard), 35° and 30°. The highest carpal extension angle from three trials at each incline was examined for a significant effect of A-frame angle with height, body weight and velocity included as covariates. Results There was no significant effect of A-frame angle on the highest carpal joint extension angle for the first or second limb. The adjusted mean carpal extension angle for the first limb at 40° was 64° [95% confidence interval (CI), 60–68), at 35° was 61° (95% CI, 57–65) and at 30° was 62° (95% CI, 59–65). The raw mean carpal extension angle for all dogs across all A-frame angles for the first limb was 62° (95% CI, 60–64) and the second limb was 61° (95% CI, 59–63). Clinical Significance Decreasing the A-frame angle of incline from 40° to 30° did not result in reduced carpal extension angles. The failure to find a difference and the narrow CI of the carpal angles may indicate that the physiologic limits of carpal extension were reached at all A-frame angles.
Publisher: Elsevier BV
Date: 12-2020
Publisher: SAGE Publications
Date: 09-06-2009
Abstract: Common lower limb postures have been found when noncontact anterior cruciate ligament (ACL) injuries occur during sidestep cutting tasks. These same postures have been linked to knee loadings known to stress the ACL. Whole body technique modification would reduce knee loading. Controlled laboratory study. Experienced team sport athletes were recruited for whole body sidestep cutting technique modification. Before and after a 6-week technique modification training, participants performed sidestep cutting tasks while ground-reaction force and motion data were collected. A kinematic and inverse dynamics model was used to calculate 3-dimensional knee loading during sidestep cutting. At initial foot contact, the participants placed their stance foot closer to the body’s midline and held their torso more upright, in line with the aims of the technique modification training. This was accompanied by significantly lower peak valgus moments in the weight acceptance phase of stance. Both postural changes were correlated with the change in peak valgus moment. Whole body sidestep cutting technique modification resulted in reduced knee loading. Implementation of whole body technique modification may produce effective ACL injury prevention programs in sports involving sidestep cutting.
Publisher: SAGE Publications
Date: 18-04-2017
Abstract: Altered knee joint biomechanics is thought to play a role in the pathogenesis of knee osteoarthritis and has been reported in patients after arthroscopic partial meniscectomy (APM) while performing various activities. Longitudinally, understanding knee joint biomechanics during jogging may assist future studies to assess the implications of jogging on knee joint health in this population. To investigate knee joint biomechanics during jogging in patients 3 months after APM and a healthy control group at baseline and 2 years later at follow-up. Controlled laboratory study. Seventy-eight patients who underwent medial APM and 38 healthy controls underwent a 3-dimensional motion analysis during barefoot overground jogging at baseline. Sixty-four patients who underwent APM and 23 controls returned at follow-up. External peak moments (flexion and adduction) and the peak knee flexion angle during stance were evaluated for the APM leg, non-APM leg (nonoperated leg), and control leg. At baseline, the peak knee flexion angle was 1.4° lower in the APM leg compared with the non-APM leg ( P = .03). No differences were found between the moments in the APM leg compared with the control leg (all P .05). However, the normalized peak knee adduction moment was 35% higher in the non-APM leg compared with the control leg ( P = .008). In the non-APM leg, the normalized peak knee adduction and flexion moments were higher compared with the APM leg by 16% and 10%, respectively, at baseline ( P ≤ .004). Despite the increase in the peak knee flexion moment in the APM leg compared with the non-APM leg ( P .001), there were no differences in the peak knee flexion moment or any other parameter assessed at 2-year follow-up between the legs ( P .05). Comparing the APM leg and control leg, no differences in knee joint biomechanics during jogging for the variables assessed were observed. Higher knee moments in the non-APM leg may have clinical implications for the noninvolved leg. Kinematic differences were small (~1.4°) and therefore of questionable clinical relevance. These results may facilitate future clinical research regarding the implications of jogging on knee joint health in middle-aged, overweight patients after APM.
Publisher: Hindawi Limited
Date: 2018
DOI: 10.1155/2018/8376030
Abstract: This study measured and compared the frequency, magnitude, and distribution of head impacts sustained by junior and adult Australian football players, respectively, and between player positions over a season of games. Twelve junior and twelve adult players were tracked using a skin-mounted impact sensor. Head impact exposure, including frequency, magnitude, and location of impacts, was quantified using previously established methods. Over the collection period, there were no significant differences in the impact frequency between junior and adult players. However, there was a significant increase in the frequency of head impacts for midfielders in both grades once we accounted for player position. A comparable amount of head impacts in both junior and adult players has implications for Australian football regarding player safety and medical coverage as younger players sustained similar impact levels as adult players. The other implication of a higher impact profile within midfielders is that, by targeting education and prevention strategies, a decrease in the incidence of sports-related concussion may result.
Publisher: BMJ
Date: 30-04-2012
DOI: 10.1136/BJSPORTS-2011-090829
Abstract: Determine if balance and technique training (BTT) implemented adjunct to normal Australian football (AF) training reduces external knee loading during sidestepping. Additionally, the authors determined if an athlete's knee joint kinematics and kinetics change over a season of AF. Eight amateur-level AF clubs (n=1,001 males) volunteered to participate in either 28 weeks of BTT or a 'sham' training (ST) adjunct to their normal preseason and regular training. A subset of 34 athletes (BTT, n=20 ST, n=14) were recruited for biomechanical testing in weeks 1-7 and 18-25 of the 28-week training intervention. During biomechanical testing, participants completed a series running, preplanned (PpSS) and unplanned sidestepping (UnSS) tasks. A linear mixed model (α=0.05) was used to determine if knee kinematics and peak moments during PpSS and UnSS were influenced by BTT and/or a season of AF. Both training groups significantly (p=0.025) decreased their peak internal-rotation knee moments during PpSS, and significantly (p=0.022) increased their peak valgus knee moments during UnSS following their respective training interventions. BTT was not effective in changing an athlete's knee joint biomechanics during sidestepping when conducted in 'real-world' training environments. Following normal AF training, the players had different changes to their knee joint biomechanics during both preplanned and unplanned sidestepping. When performing an unplanned sidestepping task in the latter half of a playing season, athletes are at an increased risk of ACL injury. The authors therefore recommend both sidestepping tasks are performed during biomechanical testing when assessing the effectiveness of prophylactic training protocols.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2013
Publisher: Springer Science and Business Media LLC
Date: 07-06-2012
DOI: 10.1007/S00167-012-2075-6
Abstract: To examine the relationship between tibiofemoral and patellofemoral joint articular cartilage and subchondral bone in the medial and gait biomechanics following partial medial meniscectomy. For this cross-sectional study, 122 patients aged 30-55 years, without evidence of knee osteoarthritis at arthroscopic partial medial meniscectomy, underwent gait analysis and MRI on the operated knee once for each sub-cohort of 3 months, 2 years, or 4 years post-surgery. Cartilage volume, cartilage defects, and bone size were assessed from the MRI using validated methods. The 1st peak in the knee adduction moment, knee adduction moment impulse, 1st peak in the knee flexion moment, knee extension range of motion, and the heel strike transient from the vertical ground reaction force trace were identified from the gait data. Increased knee stance phase range of motion was associated with decreased patella cartilage volume (B = -17.9 (95% CI -35.4, -0.4) p = 0.045) while knee adduction moment impulse was associated with increased medial tibial plateau area (B = 7.7 (95% CI 0.9, 13.3) p = 0.025). A number of other variables approached significance. Knee joint biomechanics exhibited by persons who had undergone arthroscopic partial meniscectomy gait may go some way to explaining the morphological degeneration observed at the patellofemoral and tibiofemoral compartments of the knee as patients progress from surgery. III.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2010
Publisher: Springer Science and Business Media LLC
Date: 03-09-2018
DOI: 10.1007/S40279-018-0981-6
Abstract: Adolescent cricket pace bowlers are prone to non-contact shoulder, low back and lower-limb injuries. Exercise-based injury prevention programmes (IPPs) are effective for reducing non-contact injuries in athletes however, a specific programme for adolescent pace bowlers has not been published. This paper therefore seeks to provide a rationale for the development of an exercise-based IPP specific for adolescent pace bowlers. It also outlines design principles and provides an ex le exercise programme that can be implemented at the community level. In addition, the paper addresses other injury prevention techniques concerned with the prescription of appropriate bowling loads and the modification of poor bowling biomechanics. Performing an exercise-based IPP before cricket training could reduce injury rates in adolescent pace bowlers. Eccentric strengthening exercises can be employed to target injuries to the posterior shoulder muscles, hip adductors and hamstring muscles. The risk of low back, knee and ankle injury could also be reduced with the inclusion of dynamic neuromuscular control exercises and trunk extensor endurance exercises. Other prevention strategies that need to be considered include the modification of poor bowling biomechanics, such as shoulder counter-rotation and lateral trunk flexion. Coaches and players should also aim to quantify bowling load accurately and coaches should use this information to prescribe appropriate in idualised bowling loads. Specifically, players would benefit from avoiding both long periods of low load and acute periods when load is excessively high. Future evidence is needed to determine the effectiveness of the ex le programme outlined in this paper. It would also be beneficial to investigate whether the modification of bowling biomechanics is achievable at the non-elite level and if bowling load can be accurately measured and manipulated within a community-level population.
Publisher: SAGE Publications
Date: 22-01-2015
Abstract: Background. The mirror neuron network provides a neural mechanism to prime the motor system through action observation in stroke survivors. Objective. To examine whether action observation training with immediate physical practice improves upper-limb function in chronic stroke. Methods. In a within-subject design, 14 chronic stroke survivors were assessed at baseline, then participated in 2 weeks of relaxation-sham plus physical practice (control) and reassessed. Thereafter, they participated in 2 weeks of action observation training coupled with immediate physical practice (intervention), followed by a final assessment. Duration of each action observation video sequence (priming exposure) was 30 s followed immediately by practice of the observed motor skill. Results. There were significant improvements in control and intervention phases on primary outcome measures—Upper Extremity Fugl-Meyer Motor Assessment (FMA) and Functional Test of the Hemiparetic Upper Extremity (FTHUE)—as well as secondary outcome measures of self-perceptions of arm use. Gains in the primary outcomes were greater during the intervention phase (action observation + physical practice FMA, 10.64 FTHUE level, 0.79, and tasks, 1.57) than during the control phase (relaxation-sham plus physical practice FMA, 6.64 FTHUE level, 0.43, and tasks, 1.00). Interviews with participants highlighted the added value of watching an actor perform the movement before physically attempting to perform the action. Conclusions. This study provides preliminary evidence of the additive value of action observation plus physical practice over relaxation-sham plus physical practice. There appears to be capacity for further recovery of upper-limb function in chronic stroke that persists at least in the short term.
Publisher: Springer Science and Business Media LLC
Date: 23-07-2020
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.JBIOMECH.2014.07.029
Abstract: People following arthroscopic partial medial meniscectomy (APM) are at increased risk of developing knee osteoarthritis. High impact loading and peak loading early in the stance phase of gait may play a role in the pathogenesis of knee osteoarthritis. This was a secondary analysis of longitudinal data to investigate loading-related indices at baseline in an APM group (3 months post-surgery) and a healthy control group, and again 2 years later (follow-up). At baseline, 82 participants with medial APM and 38 healthy controls were assessed, with 66 and 23 re-assessed at follow-up, respectively. Outcome measures included: (i) heel strike transient (HST) presence and magnitude, (ii) maximum loading rate, (iii) peak vertical force (Fz) during early stance. At baseline, maximum loading rate was lower in the operated leg (APM) and non-operated leg (non-APM leg) compared to controls (p ≤ 0.03) and peak Fz was lower in the APM leg compared to non-APM leg (p ≤ 0.01). Over 2 years, peak Fz increased in the APM leg compared to the non-APM leg and controls (p ≤ 0.01). Following recent APM, people may adapt their gait to protect the operated knee from excessive loads, as evidenced by a lower maximum loading rate in the APM leg compared to controls, and a reduced peak Fz in the APM leg compared to the non-APM leg. No differences at follow-up may suggest an eventual return to more typical gait. However, the increase in peak Fz in the APM leg may be of concern for long-term joint health given the compromised function of the meniscus.
Publisher: Elsevier BV
Date: 05-2020
DOI: 10.1016/J.JSAMS.2019.12.009
Abstract: To investigate if an exercise-based injury prevention program (IPP) can modify risk factors for injury in community-level adolescent cricket pace bowlers. Cluster-randomised controlled trial. Eight cricket organisations (training two times per week and no previous involvement in a structured IPP) participated in this cluster-randomised trial. Participants were aged 14-17 years, injury free, and not currently performing a rehabilitation/exercise program. Cricket organisations (clusters) were block-randomised by computerised number generation into an intervention group (performed an eight-week IPP at training) or control group (continued their usual cricket activity). Participants were not blinded to group allocation. Strength, endurance, and neuromuscular control were assessed at baseline and follow-up. Treatment effects were estimated using linear mixed models. Sixty-five male adolescent pace bowlers (intervention n=32 and control n=33) were randomised. There were significant treatment effects favouring the intervention group for shoulder strength (90°/s) 0.05 (95% CI 0.02-0.09) Nm/kg, hamstring strength (60°/s) 0.32 (95% CI 0.13-0.50) Nm/kg, hip adductor strength dominant 0.40 (95% CI 0.26-0.55) Nm/kg and non-dominant 0.33 (95% CI 0.20-0.47) Nm/kg, SEBT reach distance dominant 3.80 (95% CI 1.63-6.04) percent of leg length (%LL) and non-dominant 3.60 (95% CI 1.43-5.78) %LL, and back endurance 20.4 (95% CI 4.80-36.0) seconds. No differences were observed for shoulder strength (180°/s) (p=0.09), hamstring strength (180°/s) (p=0.07), lumbopelvic stability (p=0.90), and single leg squat knee valgus angle (dominant p=0.06, non-dominant p=0.15). Exercise-based IPPs can modify risk factors for injury in community-level adolescent pace bowlers. Future research is needed to confirm if IPPs can also reduce injury risk in this population.
Publisher: American Psychological Association (APA)
Date: 09-2019
DOI: 10.1037/XAP0000208
Abstract: This experiment investigated the contribution of visual and additive motor experience to improvement of visual anticipation. Club cricket batters were randomized into (a) a visual-perceptual group that received temporal occlusion training (n = 13), (b) a visuomotor group that received temporal occlusion training coupled with motor pattern practice of the observed bowler's action (n = 13), and (c) a no-training control group (n = 13). They completed a fast bowler video-based temporal occlusion prepost anticipation test, as well as a transfer temporal occlusion test that included different fast and slow bowlers. Results indicated visual-perceptual and visuomotor groups equally improved pick up of advance cues across prepost tests. Additive motor pattern practice for the visuomotor group facilitated superior anticipation through earlier pick up of advance information across the transfer tests. No improvement was found for the control group. The findings indicate that visual and combined motor experience facilitates learning, but additive motor experience facilitates superior transfer. Findings have implications for theoretical and applied knowledge to develop anticipation skill. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2014
Publisher: Springer Science and Business Media LLC
Date: 27-03-2015
DOI: 10.3758/S13414-015-0876-7
Abstract: Expertise studies into visual perceptual-motor skills have mainly focused their investigation upon group comparisons rather than in idual comparisons. This study investigated the pick-up of visual information to time weight transfer and bat kinematics within an exemplar group of striking sport experts using an in situ temporal occlusion paradigm. Highly skilled cricket batsmen faced bowlers and attempted to strike delivered balls, whilst their vision was either temporally occluded through occlusion glasses prior to ball bounce or not occluded (control condition). A chronometric analysis was conducted on trials in the occlusion condition to quantify the pick-up of visual information to time biomechanical variables. Results indicated that initiation of weight transfer and bat downswing, as well as bat downswing completion, was significantly different between some in idual batsmen. No significant difference was found between in idual batsmen for time of weight transfer completion. Unexpectedly, it was found that achievement of the goal to strike delivered balls, that is, the frequency of bat-ball contacts was not significantly different between batsmen. Collectively, the findings indicate that in idual differences exist in the coordination pattern of a complex whole body visual perceptual-motor skill, but these different patterns are used to achieve a similar outcome, which is known as motor equivalence.
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.JSAMS.2012.08.007
Abstract: To compare physical activity levels, subject-reported function, and knee strength in 21 arthroscopic partial meniscectomy (APM) patients (age 45.7 (6.06) years, BMI 27.3 (5.96) female 60%) 3 months post-surgery with 21 healthy controls (age 43.6 (5.71) years, BMI 24.5(4.2) female 60%) matched at the cohort level for age, gender and BMI. Case control study. Physical activity intensity, number of steps, and minutes spent in activity were objectively quantified using an accelerometer-based activity monitor worn for 7 days. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and concentric quadriceps strength were used to evaluate function post-surgery. Differences in activity levels and functional outcomes between the APM and control participants were assessed using t-tests, while multiple linear regression was used to quantify the best predictors of physical activity. APM patients engaged in a similar duration of activity to controls (469.0 (128.39)min vs. 497.1 (109.9)min), and take a similar number of steps per day (9227 (2977) vs. 10,383 (3501), but performed their activity at lower levels of intensity than controls. Time spent in moderate (r(2)=0.19) and hard (r(2)=0.145) intensity physical activity was best predicted by the Symptoms sub-scale of the KOOS for both controls and APM patients. APM patients participate in similar levels of activity at lower intensities, but with reduced activity at higher intensities which is related to the presence of symptoms of knee osteoarthritis.
Publisher: Wiley
Date: 27-03-2012
DOI: 10.1002/PIP.2180
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2019
DOI: 10.1519/JSC.0000000000003007
Abstract: Hughes, LJ, Banyard, HG, Dempsey, AR, Peiffer, JJ, and Scott, BR. Using load-velocity relationships to quantify training-induced fatigue. J Strength Cond Res 33(3): 762–773, 2019—The purpose of this study was to investigate using load-velocity relationships to quantify fluctuations in maximal strength (1 repetition maximum [1RM]), which occur as a result of training-induced fatigue. The 19 well-trained men (age: 24.3 ± 2.9 years, height: 180.1 ± 5.9 cm, body mass: 84.2 ± 10.5 kg, and squat 1RM: 151.1 ± 25.7 kg) who were recruited for this study attended 5 sessions. After baseline strength testing, in idual load-velocity relationships were established using mean concentric velocity during visits 2, 4, and 5, with visit 3 consisting of a bout of fatiguing exercise (5 sets of squats performed to muscular failure with 70% 1RM). Predicted 1RM values were calculated using the minimal velocity threshold (1RM MVT ), load at zero velocity (1RM LD0 ), and force-velocity (1RM FV ) methods. Measured 1RM, maximal voluntary contractions, and perceived muscle soreness were used to examine the effects of fatigue in relation to the predicted 1RM scores. The 1RM MVT and 1RM LD0 demonstrated very strong and strong correlations with measured 1RM during each of the sessions ( r = 0.90–0.96 and r = 0.77–0.84, respectively), while no strong significant correlations were observed for the 1RM FV . Further analysis using Bland-Altman plots demonstrated substantial interin idual variation associated with each method. These results suggest that load-velocity–based 1RM predictions are not accurate enough to be used for daily training load prescription, as has been previously suggested. Nevertheless, these predictions are practical to implement during an in idual's warm-up and may be useful to indicate general fluctuations in performance potential, particularly if used in conjunction with other common monitoring methods.
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: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.APMR.2014.04.019
Abstract: To explore the bivariate and multivariate relations between fatty degeneration of the lumbar multifidus muscle (LMM) and LMM function among patients with low back pain (LBP). Cross-sectional clinical study. Hospital. Patients with LBP (N=70) referred for lumbar spine magnetic resonance imaging. Not applicable. LMM morphology and function were measured at the L4/L5 and L5/S1 spinal levels bilaterally. Quantitative measures of LMM intramuscular adipose tissue (IMAT) were derived from T1-weighted magnetic resonance images. Function was assessed with ultrasound imaging by measuring change in LMM thickness during a submaximal contraction task. The study participants self-reported their level of LBP-related disability (Modified Oswestry Index), pain intensity (numerical pain rating scale), and physical activity (International Physical Activity Questionnaire). Bivariate and multivariate relations between LMM morphology and function were explored with correlational and hierarchical linear regression analyses, respectively. Additionally, we explored for possible covariates with potential to modify the relation between LMM IMAT and function. There were 70 participants (12 women) enrolled in the study (mean age, 45.4±11.9y). A high level of physical activity was reported by 45.5% of participates. Age, sex, and physical activity level demonstrated variable relations with LMM IMAT and LMM function. There were no significant bivariate or multivariate relations between LMM IMAT and LMM function. We observed higher levels of physical activity and LMM function and less LMM IMAT than previous studies involving patients with LBP. There was no relation between LMM morphology and function in this cohort of patients with LBP. Issues specific to LMM measurement and recommendations for future research are discussed.
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.CLINBIOMECH.2011.12.001
Abstract: Athletes suffering an anterior cruciate ligament injury tend to exhibit similar body postures that in sidestep cutting are associated with increased knee moments. This relationship, however, has not been investigated in landing. Catching a ball in different overhead positions may affect landing postures and knee joint moments. This study investigated these possible relationships. It was anticipated that some joint postures would be associated increased knee loads during the landing task. Twenty-five healthy male team sports athletes performed four variations of a landing task. Full body kinematics were identified at initial contact. Peak flexion, valgus and internal rotation moments at the knee, measured during early landing, were normalized to mass and height and statistically compared. Intra-participant correlations were performed between all kinematics and each moment. Mean slopes for each correlation were used to identify the existence of relationships between full body kinematics and knee joint moments. Findings Landing after an overhead catch when the ball moved towards a player's support leg resulted in increased peak valgus moments. These increased valgus moments were correlated with increased knee flexion, hip flexion, and torso lean, as well as torso rotation towards the support leg, and foot and knee external rotation. Increased internal rotation moments were correlated with reduced hip abduction and external rotation, increased ankle inversion, knee external rotation and torso lean away from the support leg. Interpretation Learning to land with techniques that do not reflect postures associated with high knee moments may reduce an athlete's risk of non-contact anterior cruciate ligament injury.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2019
DOI: 10.1519/JSC.0000000000002550
Abstract: Hughes, LJ, Banyard, HG, Dempsey, AR, and Scott, BR. Using a load-velocity relationship to predict one repetition maximum in free-weight exercise: a comparison of the different methods. J Strength Cond Res 33(9): 2409–2419, 2019—The purpose of this study was to investigate the reliability and validity of predicting 1 repetition maximum (1RM) in trained in iduals using a load-velocity relationship. Twenty strength-trained men (age: 24.3 ± 2.9 years, height: 180.1 ± 5.9 cm, and body mass: 84.2 ± 10.5 kg) were recruited and visited the laboratory on 3 occasions. The load-velocity relationship was developed using the mean concentric velocity of repetitions performed at loads between 20 and 90% 1RM. Predicted 1RM was calculated using 3 different methods discussed in existing research: minimal velocity threshold 1RM (1RM MVT ), load at zero velocity 1RM (1RM LD0 ), and force-velocity 1RM methods (1RM FV ). The reliability of 1RM predictions was examined using intraclass correlation coefficient (ICC) and coefficient of variation (CV). 1RM MVT demonstrated the highest reliability (ICC = 0.92–0.96, CV = 3.6–5.0%), followed by 1RM LD0 (ICC = 0.78–0.82, CV = 8.2–8.6%) and 1RM FV (ICC = −0.28 to 0.00, CV = N/A). Both 1RM MVT and 1RM LD0 were very strongly correlated with measured 1RM ( r = 0.91–0.95). The only method which was not significantly different to measured 1RM was the 1RM LD0 method. However, when analyzed on an in idual basis (using Bland-Altman plots), all methods exhibited a high degree of variability. Overall, the results suggest that the 1RM MVT and 1RM LD0 predicted 1RM values could be used to monitor strength progress in trained in iduals without the need for maximal testing. However, given the significant differences between 1RM MVT and measured 1RM, and the high variability associated with in idual predictions performed using each method, they cannot be used interchangeably therefore, it is recommended that predicted 1RM is not used to prescribe training loads as has been previously suggested.
Publisher: Georg Thieme Verlag KG
Date: 31-01-2019
Abstract: Objective The main purpose of this study was to investigate the effect of a decrease in the A-frame angle of incline on the vertical and cranio-caudal ground reaction forces observed in a homogeneous cohort of agility dogs during entrance and contact with the A-frame. Materials and Methods A crossover study design was applied to eight large breed dogs to compare the vertical and cranio-caudal ground reaction forces entering the A-frame at three angles of incline: 40° (standard), 35° and 30°. The peak vertical force, passive impact peak, peak propulsive force, peak braking force, the time point (percentile) in the stance phase at which these events occurred and the proportion of time for limb contact spent in braking (% braking) and propulsion (% propulsion) were examined. The variables measured from three trials at each incline were evaluated for a significant effect of A-frame angle with height and velocity included as covariates. Results The peak propulsive force and the % propulsion were significantly higher at the 40° angle of incline compared with 30° (p = 0.013, p = 0.0165 respectively) and the % braking was significantly lower at the 40° angle of incline compared with 30° (p = 0.0165). There was no significant effect of A-frame angle on the vertical ground reaction forces measured. Clinical Significance Compared with 30° incline, ascent up the A-frame at a 40° incline requires a higher propulsive force and extended time in propulsion to maintain forward movement and convert potential energy into forward kinetic energy.
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.JSAMS.2018.03.011
Abstract: Sport-related concussion (SRC) research has focused on impaired oculomotor function. The King-Devick (K-D) test measures oculomotor performance and is reported to identify suboptimal brain function. The use of the K-D test in Australian football (AF), a sport involving body contact and tackling, has not been documented. Therefore, the objective of this study was to determine the test-retest reliability and diagnostic accuracy of the K-D test on a sub-elite AF team. Prospective cohort study METHODS: In total, 22 male players (19.6+2.3 years) were tested and re-tested on the K-D test. Those suspected of having a SRC secondary to a significant head impact were tested. Randomly selected additional players without SRC were assessed for comparison. There were observable learning effects between the first and second baseline testing (48 vs. 46s). The ICC for the first and second baseline tests was 0.91. Post-match test times were longer than the baseline times for players with SRC (n=7) (-1.9s z=-5.08 p<0.0001). Players tested with no signs of SRC (n=13) had an improvement in time when compared with their baseline score (3.0s z=-4.38 p<0.0001). The overall sensitivity was 0.98, specificity 0.96, and a kappa of κ=0.94. The positive likelihood ratio was 11.6 and the positive predictive value was 89.0%. This study supports the use of the K-D test due to its test-retest reliability, high sensitivity and specificity, and fast and simple use that is ideal for sports medicine professionals to make quick judgement on management and playability.
Publisher: Informa UK Limited
Date: 04-04-2023
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.CLINBIOMECH.2014.07.002
Abstract: Knee osteoarthritis is common following arthroscopic partial meniscectomy and a higher external peak knee adduction moment is believed to be a contributor. The peak knee adduction moment has been shown to increase over 2 years (from 3-months post-arthroscopic partial meniscectomy). The aim of this study was to evaluate mechanisms underpinning the increase in peak knee adduction moment over 2 years observed in people 3-months following arthroscopic partial meniscectomy. Sixty-six participants with medial arthroscopic partial meniscectomy were assessed at baseline and again 2 years later. Parameters were evaluated at time of peak knee adduction moment as participants walked barefoot at their self-selected normal and fast pace for both time points. For normal pace walking, an increase in frontal plane ground reaction force-to-knee lever arm accounted for 30% of the increase in peak knee adduction moment (B=0.806 [95% CI 0.501-1.110], P<0.001). For fast pace walking, an increase in the frontal plane ground reaction force magnitude accounted for 21% of the increase in peak knee adduction moment (B=2.343 [95% CI 1.219-3.468], P<0.001) with an increase in tibia varus angle accounting for a further 15% (B=0.310 [95% CI 0.145-0.474], P<0.001). Our data suggest that an increase in lever arm and increase in frontal plane ground reaction force magnitude are contributors to the increased knee adduction moment observed over time in people following arthroscopic partial meniscectomy.
Publisher: Informa UK Limited
Date: 03-12-2020
Publisher: BMJ
Date: 18-09-2014
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.JSAMS.2014.04.012
Abstract: Determine if balance and technique training implemented adjunct to 1001 male Australian football players' training influenced the activation/strength of the muscles crossing the knee during pre-planned and unplanned sidestepping. Randomized Control Trial. Each Australian football player participated in either 28 weeks of balance and technique training or 'sham' training. Twenty-eight Australian football players (balance and technique training, n=12 'sham' training, n=16) completed biomechanical testing pre-to-post training. Peak knee moments and directed co-contraction ratios in three degrees of freedom, as well as total muscle activation were calculated during pre-planned and unplanned sidestepping. No significant differences in muscle activation/strength were observed between the 'sham' training and balance and technique training groups. Following a season of Australian football, knee extensor (p=0.023) and semimembranosus (p=0.006) muscle activation increased during both pre-planned sidestepping and unplanned sidestepping. Following a season of Australian football, total muscle activation was 30% lower and peak valgus knee moments 80% greater (p=0.022) during unplanned sidestepping when compared with pre-planned sidestepping. When implemented in a community level training environment, balance and technique training was not effective in changing the activation of the muscles crossing the knee during sidestepping. Following a season of Australian football, players are better able to support both frontal and sagittal plane knee moments. When compared to pre-planned sidestepping, Australian football players may be at increased risk of anterior cruciate ligament injury during unplanned sidestepping in the latter half of an Australian football season.
Publisher: SAGE Publications
Date: 10-2014
Abstract: This pilot study integrated sport expertise and biomechanics methodologies within a baseball batting task. Purpose was to examine differences within a highly skilled group of baseball batters to use visual information to guide weight transfer and bat movements. One batter who played at Major League Baseball (MLB) level was compared to five batters who played at Australian Baseball League (ABL) level in a case-control design. Batters faced pitchers in a simulated competition and attempted to hit pitches, while vision was temporally occluded during ball flight or not occluded. Time of weight transfer (kinetics), as well as bat downswing initiation and duration (kinematics) from the point of ball release, were compared between the MLB batter and ABL batters. Results indicated that the MLB batter coordinated his striking pattern by completing his weight transfer earlier than the ABL batters. His bat downswing was also initiated earlier than some ABL batters, but there was no difference in duration of bat downswing between batters. All batters initiated bat downswing prior to completion of weight transfer. Understanding of motor expertise is furthered using a novel methodology.
Publisher: Wiley
Date: 04-03-2011
DOI: 10.1002/JOR.21396
Abstract: The objective of this work is to evaluate differences in trabecular bone (TB) texture between subjects with and without tibiofemoral cartilage defects using a variance orientation transform (VOT) method. A case-control study was performed in subjects without radiographic knee osteoarthritis (OA) (K&L grade <2) matched on sex, BMI, age, knee compartment, and meniscectomy where cases (n = 28) had cartilage defects (grade ≥2) and controls (n = 28) had no cartilage defects (grade <2). Cartilage defects were assessed from MRI using validated methods. The VOT was applied to TB regions selected on medial and lateral compartments in knee X-rays and fractal signatures (FS) in the horizontal (FS(H) ) and vertical (FS(V) ) directions, and along the roughest part of TB (FS(Sta) ) and texture aspect ratio signatures (StrS), at different trabecular image sizes (0.30-0.70 mm) were calculated. Compared with controls, FS(V) for cases were higher (p < 0.011) at image sizes 0.30-0.40 mm and 0.45-0.55 mm in the medial compartment. In the lateral compartment, FS(H) and FS(Sta) for cases were higher (p < 0.028) than those for controls at 0.30-0.40 mm and 0.45-0.55 mm, while FS(V) was higher (p 0.05) were found.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2014
Publisher: Springer Science and Business Media LLC
Date: 27-10-2017
DOI: 10.1007/S00167-015-3831-1
Abstract: To examine differences in cartilage morphology between young adults 2-3 years post-anterior cruciate ligament reconstruction (ACLR), with or without meniscal pathology, and control participants. Knee MRI was performed on 130 participants aged 18-40 years (62 with isolated ACLR, 38 with combined ACLR and meniscal pathology, and 30 healthy controls). Cartilage defects, cartilage volume and bone marrow lesions (BMLs) were assessed from MRI using validated methods. Cartilage defects were more prevalent in the isolated ACLR (69 %) and combined group (84 %) than in controls (10 %, P < 0.001). Furthermore, the combined group showed higher prevalence of cartilage defects on medial femoral condyle (OR 4.7, 95 % CI 1.3-16.6) and patella (OR 7.8, 95 % CI 1.5-40.7) than the isolated ACLR group. Cartilage volume was lower in both ACLR groups compared with controls (medial tibia, lateral tibia and patella, P < 0.05), whilst prevalence of BMLs was higher on lateral tibia (P < 0.001), with no significant differences between the two ACLR groups for either measure. Cartilage morphology was worse in ACLR patients compared with healthy controls. ACLR patients with associated meniscal pathology have a higher prevalence of cartilage defects than ACLR patients without meniscal pathology. The findings suggest that concomitant meniscal pathology may lead to a greater risk of future OA than isolated ACLR. III.
Publisher: Human Kinetics
Date: 04-2014
Abstract: Anterior cruciate ligament (ACL) injuries are costly. Sidestep technique training reduces knee moments that load the ACL. This study examined whether landing technique training alters knee moments. Nineteen team sport athletes completed the study. Motion analysis and ground reaction forces were recorded before and after 6 weeks of technique modification. An inverse dynamic model was used to calculate three-dimensional knee loading. Pre- and postintervention scores were compared using paired t tests. Maximal knee flexion angle during landing was increased following training. There was no change in valgus or flexion moments, but an increase in peak internal rotation moment. This increase in internal rotation moment may increase the risk of ACL injury. However, the increased angle at which the peak internal rotation moment occurred at follow up may mitigate any increase in injury risk by reducing load transmission.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2016
DOI: 10.1519/JSC.0000000000001379
Abstract: Teo, SYM, Newton, MJ, Newton, RU, Dempsey, AR, and Fairchild, TJ. Comparing the effectiveness of a short-term vertical jump vs. weightlifting program on athletic power development. J Strength Cond Res 30(10): 2741–2748, 2016—Efficient training of neuromuscular power and the translation of this power to sport-specific tasks is a key objective in the preparation of athletes involved in team-based sports. The purpose of this study was to compare changes in center of mass (COM) neuromuscular power and performance of sport-specific tasks after short-term (6-week) training adopting either Olympic-style weightlifting (WL) exercises or vertical jump (VJ) exercises. Twenty-six recreationally active men (18–30 years height: 178.7 ± 8.3 cm mass: 78.6 ± 12.2 kg) were randomly allocated to either a WL or VJ training group and performance during the countermovement jump (CMJ), squat jump (SJ), depth jump (DJ), 20-m sprint, and the 5-0-5 agility test–assessed pre and posttraining. Despite the WL group demonstrating larger increases in peak power output during the CMJ (WL group: 10% increase, d = 0.701 VJ group: 5.78% increase, d = 0.328) and SJ (WL group: 12.73% increase, d = 0.854 VJ group: 7.27% increase, d = 0.382), no significant between-group differences were observed in any outcome measure studied. There was a significant main effect of time observed for the 3 VJs (CMJ, SJ, and DJ), 0- to 5-m and 0- to 20-m sprint times, and the 5-0-5 agility test time, which were all shown to improve after the training (all main effects of time p 0.01). Irrespective of the training approach adopted by coaches or athletes, addition of either WL or VJ training for development of power can improve performance in tasks associated with team-based sports, even in athletes with limited preseason training periods.
Publisher: Informa UK Limited
Date: 03-02-2016
DOI: 10.1080/17461391.2015.1135985
Abstract: Adolescent fast bowlers are prone to sustaining lumbar injuries. Numerous components have been identified as contributing factors however, there is limited empirical evidence outlining how the muscles of the lumbopelvic region, which play a vital role in stabilising the spine, function during the bowling action and the influence of such activation on injuries in the fast bowler. Surface electromyography was utilised to measure the function of the lumbar erector spinae, lumbar multifidus, gluteus medius and gluteus maximus muscles bilaterally during the fast bowling action in a group of 35 cricket fast bowlers aged 12-16 years. Two prominent periods of activation occurred in each of the muscles examined. The period of greatest mean activation in the erector spinae and multifidus occurred near back foot contact (BFC) and within the post-ball-release (BR) phase. The period of greatest mean activation for the gluteus medius and gluteus maximus occurred during phases of ipsilateral foot contact. The greatest periods of muscle activation in the paraspinal and gluteal muscles occurred at times where vertical forces were high such as BFC, and in the phases near BR where substantial shear forces are present. The posterior muscles within the lumbopelvic region appear to play a prominent role during the bowling action, specifically when compressive and shear forces are high. Further research is required to substantiate these findings and establish the role of the lumbopelvic muscles in the aetiology of lumbar injury in the cricket fast bowler.
Publisher: SAGE Publications
Date: 25-08-2021
DOI: 10.1177/03635465211027946
Abstract: Sports-related concussion (SRC) assessment tools are primarily based on subjective assessments of somatic, cognitive, and psychosocial/emotional symptoms. SRC symptoms remain underreported, and objective measures of SRC impairments would be valuable to assist diagnosis. Measurable impairments to vestibular and oculomotor processing have been shown to occur after SRC and may provide valid objective assessments. Determine the diagnostic accuracy of sideline tests of vestibular and oculomotor dysfunction to identify SRC in adults. Systematic review Level of evidence, 4. Electronic databases and gray literature were searched from inception until February 12, 2020. Physically active in iduals ( years of age) who participated in sports were included. The reference standard for SRC was a combination of clinical signs and symptoms (eg, the Sport Concussion Assessment Tool [SCAT]), and index tests included any oculomotor assessment tool. The QUADAS tool was used to assess risk of bias, with the credibility of the evidence being rated according to GRADE. A total of 8 studies were included in this review. All included studies used the King-Devick test, with no other measures being identified. Meta-analysis was performed on 4 studies with a summary sensitivity and specificity of 0.77 and 0.82, respectively. The overall credibility of the evidence was rated as very low. Caution must be taken when interpreting these results given the very low credibility of the evidence, and the true summary sensitivity and specificity may substantially differ from the values calculated within this systematic review. Therefore, we recommend that clinicians using the King-Devick test to diagnose SRC in adults do so in conjunction with other tools such as the SCAT. CRD42018106632.
Publisher: Informa UK Limited
Date: 26-09-2018
DOI: 10.1080/00913847.2018.1525261
Abstract: Sport-related concussion (SRC) can result in impaired oculomotor function. Oculomotor performance, measured utilizing the King-Devick/Eye Tracking test (K-D/ET), is reported to be able to identify sub-optimal brain function. The objectives of the study were to determine the diagnostic accuracy of the K-D/ET in identifying SRC occurring from game participation and to perform a comparative analysis on saccade and blink counts for each K-D card in idually and total counts between baseline and post-concussion. Nineteen male Australian Football players were assessed on the K-D/ET test. Those suspected of having SRC secondary to a head impact were also tested. Participants recorded a slower time on the third (20.2 ± 4.6 s) screen when compared with the first (p = 0.0424) and second (p = 0.0150) screens. The number of blinks was higher on the third (2.9 ± 2.9) when compared with the second (p = 0.0057) screen. There was decrease of the K-D/ET total times between pre- and post-game (p = 0.1769). Participants who sustained a head impact recorded slower mean total K-D time (p = 0.7322), fewer mean total saccades (p = 0.0112), and more mean blinks (p = 0.8678) compared with their baseline scores. The assessment of blinks was the most sensitive measure for potential SRC (0.67). The K-D/ET duration was the most specific measure for potential SRC (0.88). An increase in the number of blinks had a fair specificity of 0.69. The rapid number-naming component of the K-D test is an assessment tool which quantifies impairment to oculomotor function and has been validated as a diagnostic tool for SRC. The clinical usefulness of the eye tracking component of the K-D/ET test is that it may be an effective method to assess concussions with the eye tracking component serving as a measure of progression and return to play. However, more research is required at the adult and youth level.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2007
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2016
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.CLINBIOMECH.2015.09.006
Abstract: Knee osteoarthritis is common in people who have undergone partial meniscectomy, and a higher external knee flexion moment during gait may be a potential contributor. Although the peak external knee flexion moment has been shown to increase from 3 months to 2 years following partial meniscectomy, mechanisms underpinning the increase in the peak knee flexion moment are unknown. Sixty-six participants with partial meniscectomy completed three-dimensional gait (normal and fast pace) and quadriceps strength assessment at baseline (3 months following partial meniscectomy) and again 2 years later. Variables included external knee flexion moment, vertical ground reaction force, knee flexion kinematics, and quadriceps peak torque. For normal pace walking, the main significant predictors of change in peak knee flexion moment were an increase in peak vertical ground reaction force (R(2)=0.55), mostly due to an increase in walking speed, and increase in peak knee flexion angle (R(2)=0.19). For fast pace walking, the main significant predictors of change in peak knee flexion moment were an in increase in peak vertical ground reaction force (R(2)=0.51) and increase in knee flexion angle at initial contact (R(2)=0.17). Change in peak vertical force was mostly due to an increase in walking speed. Findings suggest that increases in vertical ground reaction force and peak knee flexion angle during stance are predominant contributors to the 2-year change in peak knee flexion moment. Future studies are necessary to refine our understanding of joint loading and its determinants following meniscectomy.
Publisher: Springer Science and Business Media LLC
Date: 06-09-2017
DOI: 10.1007/S40279-017-0778-Z
Abstract: Adolescent cricket pace bowlers are prone to injury. Recognising the risk factors for non-contact injury in this population will aid future injury prevention strategies. To identify the risk factors for non-contact injury in adolescent cricket pace bowlers. We systematically searched PubMed, Cochrane Library, PEDro, SPORTDiscus, Embase, and the South African Journal of Sports Medicine to identify all experimental and observational studies reporting risk factors for non-contact injuries in pace bowlers (aged 12-19 years). The search syntax included terms relevant to cricket bowling, injury, and known risk factors for injury. The Newcastle-Ottawa Quality Assessment Scale and a modified Newcastle-Ottawa Quality Assessment Scale were used to assess the risk of bias in the cohort and cross-sectional studies, respectively. Sixteen studies (five cross-sectional studies, 11 cohort studies) comprising 687 participants (96% male, 75% playing cricket in Australia) met the selection criteria and were included for qualitative synthesis. Three cross-sectional studies were rated as high risk of bias and two as very high risk of bias. For the cohort studies, three were rated as low risk of bias, and eight as high risk of bias. Injury was associated with bowling biomechanics (excessive lateral trunk flexion and pelvis/hip kinematics), reduced trunk endurance, poor lumbo-pelvic-hip movement control, and early signs of lumbar bone stress. Conflicting results were found by studies examining the mixed technique, bowling workload and quadratus lumborum asymmetry. The current systematic review identified a number bowling biomechanics and various neuromuscular deficiencies as risk factors for non-contact injury in adolescent pace bowlers. These factors may provide a useful target for future interventional research aiming to prevent injury in this population. Future studies should utilise prospective cohort designs, and ensure that participants are injury-free at baseline, confounding factors are well controlled and attrition rates are reported. This systematic review was registered a priori (PROSPERO, CRD42016043956).
No related grants have been discovered for Alasdair Dempsey.