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COMPARISON OF STEP-BY-STEP KINEMATICS OF NORMAL AND ASSISTED 60 M SPRINTS WITH DIFFERENT LOADS IN EXPERIENCED SPRINTERS
Get PDFThe purpose of this study was to compare step-by-step kinematics of normal and assisted 60 m sprints with different loads in experienced sprinters. Step-by-step kinematics were measured using inertial measurement units integrated with a 3-axis gyroscope and a laser gun in eleven participants during a normal 60 m sprint and sprints with a 3, 4, or 5kg pulling force. The main findings were that using increased assisted loads resulted in faster 60 m times, which was a result of a higher step velocity caused mainly by longer step lengths. In terms of practical application, it is notable that employing this approach, when using a 5 kg assisted load can help athletes reach higher step velocities and maintain these velocities longer, which could be a training impulse to move the speed barrier upwards
CROSS RECURRENCE QUANTIFICATION ANALYSIS OF INTER-LEG RELATIONS ACROSS THE GAIT TRANSITION
Get PDFThe aim of this study was to quantify characteristics of the deterministic properties of inter-leg movements over the gait transition. The purpose was to further understanding of the nonlinear characteristics of the gait of a healthy individual. A participant locomoted on a treadmill as the speed steadily increased from 0 to 18 km/h over a 120 s period. Position of the approximate center of rotation of the bilateral toe, ankle, knee and hip, were collected (CODAmotion; 100 Hz). The mathematical addition of the four markers representing the “free leg” in the direction of travel (x direction) provided the variables “left leg” and “right leg”. Each leg was embedded with a dimension of 3 and time lag of 18 points to create the Taken’s vector. Cross Recurrent Quantification Analysis (RQA) was then performed. Two distinct phases in the combined dynamics of the leg-leg system were observed, with lower determinism in the walking phase compared to running, separated by a clear, sharp transition. Results indicate that determinism in the cross dynamics of the two legs seems to play a role similar to an order parameter for the walk-run phase transition. This work increases our understanding of the nonlinear dynamics characteristics of the gait transition
TRUNK MUSCLE ACTIVATION DURING PLANNED AND UNPLANNED SIDESTEPPING: IMPLICATIONS FOR FRONTAL PLANE TRUNK POSITIONING AND ACL INJURY RISK
Get PDFThis study compared time-varying measures of trunk muscle activation and lateral flexion between planned (PSS) and unplanned sidesteps (UPSS) in seven male participants. Fine-wire and surface electromyography signals from nine muscles characterised trunk muscle activation. Greater trunk activation was observed in UPSS during the penultimate stance and action-stance, but not during flight phase preceding the action-stance. Significant differences were observed in flight phase trunk lateral flexion angle between tasks. No differences were found in lateral contraction ratios between movement conditions. These preliminary results indicate that trunk muscle activation differences between PSS and UPSS are not sufficient to account for the increased lateral forces experienced during UPSS. Thereby, resulting in the higher trunk lateral flexion observed during UPSS
NEW DEVELOPMENTS IN VECTOR CODING METHODS FOR ASSESSING COORDINATION VARIABILITY
Get PDFThe purpose of this study is to propose modifications to current methods for the assessment of coordination variability through vector coding techniques. Commonly, vector coding starts from calculating the vector difference between adjacent data points on an angle-angle plot. This initial stage is analogue to estimating angular velocities from displacement, but with the limitation of differentiating the three axial components in isolation. Instead, the calculation of angular velocities from 3D data should take into account movement in other planes of motion. This study suggests the use of angular velocities in vector coding in place of the difference calculations and demonstrates how using this method can be integrated with recent developments which involve the use of ellipses for calculating coordination variability of angle-angle diagrams
CHANGES IN JUMP PERFORMANCE AND DYNAMIC BALANCE AT HIGH TERRESTRIAL ALTITUDE
Get PDFThe purpose of this study was to examine the effects of altitude on dynamic balance and jump performance of a controlled landing during a 12-day high altitude trek. Following a two-legged jump, time to stabilization (5% of body mass for 0.5 s), maximum power, and jump height were measured in 11 participants using a portable force platform at sea level (BL), 3619 m (C1), and 5140 m (C3). Jump performance significantly decreased at C1 and C3 compared to BL (P=0.001). There were no significant differences found in time to stabilization and maximum power with increasing altitude. The present findings indicate that jump performance is significantly decreased with increasing altitude. However, dynamic balance and jump power remain unaffected
CAN WE ALTER YOUTH ATHLETE’S LANDING STRATEGY IN A STOP-JUMP MOVEMENT?
Get PDFThe purpose of this study was to determine the effect of four different neuromuscular training programs on the kinematic landing patterns of pre elite youth athletes during a stop-jump movement. Eighty-nine pre-elite youth athletes from the Western Region Academy of Sports Basketball, Netball, Softball, Triathlete and Hockey squads were recruited for biomechanical analysis before and after the completion of one of four randomly assigned 12-week training intervention programs, in conjunction with a strength and conditioning program. Results of this study identify youth athletes with poor movement competency acquire similar alterations in their kinematic landing pattern regardless of the type of training intervention completed, identifying that a basic strength and conditioning program can implemented to alter landing technique in a stop-jump task
TRAINING LOAD PRIOR TO INJURY IN PROFESSIONAL RUGBY LEAGUE PLAYERS: ANALYSING INJURY RISK WITH MACHINE LEARNING
Get PDFThis study explores the application of Global Positioning System tracking data from field training sessions and supervised machine learning algorithms for predicting injury risk of players across a single National Rugby League season. Previous work across a range of sporting codes has demonstrated associations between training loads and increased incidence of injury in professional athletes. Most of the work conducted has applied a reductionist approach, identifying training load characteristics as risk factors using generalised models to show population trends. This study demonstrates promising results by applying processing techniques and machine learning algorithms to analyse the injury risk associated with complex training load patterns. The accuracy of the algorithms are investigated along with the importance of training load predictors and data window sizes
CHANGE IN MECHANICAL PROPERTIES OF TRICEPS SURAE MUSCLE-TENDON UNIT AND RACE PERFORMANCE AFTER 1 YEAR IN WELL TRAINED DISTANCE RUNNERS
Get PDFThe purpose of this study was to determine change in relationship between stiffness of triceps surae muscle-tendon unit and race performance after one year with continuous training in well trained long distance runners. For 9 long distance runners, official race record and stiffness indexes of both muscle and tendon were investigated in pre and post measurements (after one year). The race performance (1.9%), passive torque of ankle joint (13.2%), and muscle stiffness index (73.6%) increased significantly between pre and post. Although significant correlations were not found between increment of race performance and change in all parameters, 6 of the 9 athletes showed increments of both race performance and stiffness index of muscle tissue. These results suggest that an increment of stiffness of the ankle joint and triceps muscle could be related to improvement of race performance in distance running
CENTER OF MASS DISPLACEMENT DURING THE BADMINTON-SPECIFIC SPEED TEST
Get PDFThe purpose of this study was to identify movement strategies of elite badminton players when carrying out a badminton specific speed test. Twenty-one international elite badminton players participated with whole-body kinematics collected using 15 high-speed infrared cameras. Center of Mass (CoM) movement analysis was conducted using Visual3D (C-Motion Inc., USA). CoM energy and total power, peak CoM velocity and postural sway were analysed. Genders were compared by t-tests and relationship between completion time and the investigated parameters was tested using Pearson Correlation tests. Male players were lowering their CoM 7 cm more than females. A significant correlation was found among the male players between total power and completion time. All male players exhibited greater total power during the test and higher peak CoM velocities than female players. The results demonstrate the ability to quantify performance by tracking 3D-movements of the CoM in badminton. Future kinematic testing should include novice and non-skilled players to derive beneficial techniques and coaching strategies accordingly
MOVING ON SLOPES: ISSUES AND CHALLENGES FROM A BIOMECHANICAL PERSPECTIVE
Get PDFMoving on slopes is part of daily living locomotion, but also several sport disciplines are performed on inclined terrain. From a biomechanical perspective locomotion on slopes is a challenging task as additional work has to be done compared to locomotion on flat terrain. Moving downwards supports the locomotion due to gravity, however, steep slopes often lead to high speeds caused by the transfer of potential to kinetic energy. Then locomotion is accompanied with the challenge to control speed. Another issue is the aspect of joint loading when moving on slopes. An increase of potential or kinetic energy is associated with an enhancement of work done by the joint structures. The purpose of the presentation is to characterize the specificity and challenges when moving on slopes from a biomechanical perspective including performance, coordination, safety and joint loading in daily movement and sport related tasks