5954 research outputs found
Sort by
BIOMECHANICAL ANALYSIS OF DYNAMIC AND STATIC BALANCE WITH DIFFERENT ARM POSITION
Get PDFThis study is aimed to explore the balance of participants between arms-free and arms-control conditions with the Star Excursion Balance Test (SEBT) and Romberg\u27s Test. Twenty healthy young males volunteered to participate in the test. Optitrack Optoelectronic system was utilized to capture the spatiotemporal parameters and the three-dimensional coordinates of the lower extremities. Besides, DIERS formetric 4D system was used to analyse the motion amplitude of spine and pelvis. Arms-control could reduce the dynamic balance based on the results of SEBT, and it would increase the static balance in the instability static condition from Romberg’s Test. Results of this study have provided information on clinical evaluation using arm position during dynamic and static balance from a biomechanical perspective
FEATURE SELECTION FOR THE APPLICATION OF ARTIFICIAL NEURAL NETWORKS IN MOTION ANALYSIS
Get PDFThe application of IMUs and artificial neural networks have shown their potential in estimating joint moments in various motion tasks. In this study, IMU data collected with five sensors during gait was used as input data to estimate hip, knee and ankle joint moments using artificial neural networks. Additionally, the original 30 features of the sensors’ data were reduced to their ten most relevant principal components and also used as input to the neural networks to evaluate the influence of feature selection. The prediction accuracy of the networks was lower for the reduced dataset. Research with a larger dataset needs to be undertaken to further understand the influence of a reduced number of features on the prediction accuracy
FORCE-TIME CURVE ALIGNMENT FOR FUNCTIONAL PRINCIPAL COMPONENT ANALYSIS IN VERTICAL JUMPING
Get PDFFunctional principal component analysis (FPCA) can be used to extract key features from time series data for use in statistical models. This study evaluated time normalisation in combination with curve registration prior to performing FPCA. Using vertical ground reaction force data from countermovement jumps, evaluation was based on linear regression for predicting peak power and jump height, and logistic regression for classifying jump type (arm swing or not). Datasets not subject to time normalisation generally produced better results with the highest accuracy being achieved when using registration with peak power as a landmark (peak power R2 = 99.3%, jump height R2 = 94.9%). Classification of jump type benefited in some cases from registration (87.0% to 91.2%). These techniques could be applied to data from wearable sensors to improve prediction and classification
DIFFERENCES IN RUNNING BIOMECHANICS OF ELITE SPRINTERS, NON-ELITE SPRINTERS AND NON-RUNNERS
Get PDFThe aim of the study was to investigate key predictors of fast sprinting. For this purpose, three groups of subjects were evaluated: elite sprinters, non-elite sprinters and non-runners. The analyzed groups consisted of 7, 9 and 11 subjects, respectively. Biomechanical running parameters were collected during the 30-meter acceleration up to maximum speed achievable by the subject. The obtained results revealed clear differences in running biomechanics among the all groups (contact time and step length normalised to body height). Also group results for «step length\u3ebody height» and «RSI\u3e1 showed, that the values of these parameters are available only for elite sprinters and non- elite sprinters groups. Date also showed step length normalised to body height to be a highly informative predictor of sprint performance (its correlation coefficient with maximum speed being 0.81)
EFFECTS OF PURTURBATIONS ON KICKING LIMB CO-ORDINATION DURING THE SEPAKTAKRAW SERVE – A PRELIMINARY ANALYSIS WITH COACHING IMPLICATIONS
Get PDFThe purpose of this study was to describe kicking limb joint co-ordination between sepaktakraw serve techniques and to establish the effects of a perturbation on joint co-ordination when executing serve skills of different complexity to determine if the intended perturbations are required during training. A total of 25 kuda and 25 sila serve trials, performed by a trained male sepaktakraw player, were captured using a high-speed optical camera system. Kicking limb joint co-ordination differs between technique possibly due to differences in kicking kinematics. When subjected to perturbations (not receiving an ideal ball position in mid-air because the ball is tossed by another player), it took a longer time to return to normal kuda kicking patterns. Even with perturbations, players made adaptations to the kicking limb co-ordination and this strategy is key for repeated successful serves to unknown ball tossed positions in mid-air for optimal performance outcome measures. It is therefore recommended that perturbations be included during training so that, when perturbations occur, servers will be more aware of how to re-adjust their kicking patterns most quickly at the next serve
Reducing anterior cruciate ligament injury risk factors by training perception: How vital is maintaining the perception-action coupling?
Get PDFThis study investigated the effect of maintaining perception-action coupling during a 4-week perceptual training program aiming to reduce biomechanical risk factors associated with ACL injury. Kinetic (valgus and internal rotation knee moments) and neuromuscular (total knee muscle activation and directed co-contraction ratios) variables were calculated during evasive sidestepping of 3D-projected opponents in 1-on-1, 2-on-2 and 3-on-3 game-based situations pre and post-intervention training. An additional transfer scenario was assessed post-intervention. Twenty-six amateur Australian Rules footballers were allocated to control (C), uncoupled (U) or coupled (PA) groups. Participants completed biweekly perceptual training containing 48 trials requiring a verbal (uncoupled) or running sidestep (coupled) response while counting the number of attentional cues displayed. Training groups showed no reductions in peak valgus and internal rotation moments, however, a small decrease in peak valgus moments was observed in the transfer condition. Coupled training displayed significant group differences in medial-lateral co-contraction ratios from controls. No changes in muscle activation patterns pre-post ARF were observed, however C and UC groups redirected co-contraction ratios laterally in the transfer condition. Results suggest that attentional cueing perceptual training with a coupled response may have a beneficial impact on kinetic ACL injury risk factors and maintain muscle activation levels associated with decreased ACL injury risk
THE EFFECT OF POLO DRILL SWIMMING ON FREESTYLE KINEMATICS: A PILOT STUDY
Get PDFThe purpose of this pilot study was to compare temporal performance variables and kinematic parameters during the entry and catch phase of freestyle and Polo drill swimming. Five well-trained freestyle swimmers performed 400 m of Polo drill and freestyle through a 8.91 m3 calibrated space recorded by eight synchronised cameras. Differences were assessed by a paired t-test and effect size (d) calculations for each variable. Significant differences occurred with respect to stroke length, stroke rate, stroke duration, entry and catch duration, hip velocity and vertical displacement and trunk inclination. The finger displacement and velocity, elbow angle and shoulder displacement were not significantly different through the entry and catch phase of the stroke. This work identified that while notable differences exist between freestyle and Polo drill swimming, there is an indication that some key parameters may be similar
UNILATERAL SHOULDER PAIN IS ASSOCIATED WITH ASYMMETRIES IN TENDON THICKNESS FOLLOWING MAXIMUM EXERTION IN AN ELITE WHEELCHAIR RUGBY ATHLETE: A CASE IN POINT TOWARDS INDIVIDUALIZED FEEDBACK
Get PDFThe purpose of this study was to describe changes in tendon thickness following maximum exertion in the symptomatic and asymptomatic shoulder of a highly trained wheelchair rugby athlete with tetraplegia. Tendon thickness of the biceps and supraspinatus on both sides were measured with ultrasound before any physical tests, after a treadmill test up to maximum exertion to define aerobic capacity, and after a 30s Wingate test to define anaerobic capacity. The athlete reported moderate to severe shoulder pain, quantified with the upper extremity pain symptom questionnaire (PSQ) on the left shoulder and no pain on the right shoulder. There was a meaningful reduction (i.e., \u3e 2 x SD) in biceps and supraspinatus tendon thickness after the physical tests at the asymptomatic shoulder with no meaningful changes at the symptomatic shoulder. Reduction in tendon thickness has been related to increased alignment of the collagen fibres or creep which is a typical response to tensile loading. While the symptomatic shoulder presented a higher peak power output, there was a significantly greater drop in maximum power output during the Wingate test. Subsequently, the greater decline in power output with fatigue in the symptomatic shoulder, may have increased loads on the asymptomatic shoulder and be related to the greater reduction in tendon thickness following exertion. This demonstrates the importance to monitor and reduce asymmetries to improve performance and prevent injury and pain
DIFFERENCES IN BOAT VELOCITY RELATED TO TECHNICAL EFFICIENCY IN HIGHLY-TRAINED ROWERS
Get PDFBoat velocity is determined by both physical capacity and technical ability. By adjusting for power, we quantified differences in velocity attributable to technical efficiency. Stroke data from 47 2000 m races in male and female single sculls (10 and 8 boats) and coxless pairs (3 and 6 boats) were collected using Peach PowerLine and OptimEye S5 GPS equipment attached to boats. The logarithm of velocity was predicted with the logarithm of the sum of mean stroke power of both oars in a general linear mixed model for each boat class, a random effect for boat identity estimated a coefficient of variation representing differences in efficiency between boats. The differences were very large to extremely large (CV of 1.3-3.4%). Performance of boats with poor efficiency could be enhanced by improving technique, improving power output could be the focus for those with good efficiency
THE PHYSIOLOGICAL AND PSYCHOLOGICAL EFFECTS OF INDOOR VERSUS OUTDOOR AEROBIC EXERCISE IN FEMALE CANCER SURVIVORS: A LITERATURE REVIEW
Get PDFModerate aerobic exercise is advantageous to physiological and psychological well-being among healthy and diseased populations. Investigating the physiological and psychological effects of indoor and outdoor aerobic training on ROS, antioxidants, QOL, vitamin D, estrogen, kynurenine, cardiovascular disease, obesity, and the immune system within cancer patients and survivors may be imperative to their recovery and survival. Outdoor aerobic exercise within a greenery-rich environment elicits greater positive changes within overall well-being compared to outdoor exercise in an urban setting or indoor exercise. However, both indoor and outdoor aerobic exercise produce benefits in mood state, the immune system, cardiovascular health, bone health, and countering oxidative stress that damages cells. Exercise is able to help counter the psychological, cognitive, and negative physiological effects of cancer treatments. Moderate aerobic exercise helps to decrease depression and tumor proliferation through an increase in kynurenic acid and lower risk of breast cancer by an increased energy expenditure to reduce fat tissue, thus decreasing the production of estrogen in post-menopausal women. Adequate levels of vitamin D are important to combat depression and tumor proliferation as well, which can be controlled through outdoor exercise in the sun or supplementation. Cancer patients and survivors can benefit from engaging in moderate aerobic exercise in both indoor and outdoor environments, however the outdoor environment may provide more benefit psychologically