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SWIMMING PHASE-BASED PERFOMANCE EVALUATION USING A SINGLE IMU IN FRONT CRAWL
Get PDFThe purpose of this study was to assess the potential of using a sacrum-worn inertial measurement unit (IMU) for performance evaluation in each swimming phase (wall push-off, glide, stroke preparation, and swimming) of national-level swimmers in front crawl technique. Nineteen swimmers were asked to wear a sacrum IMU and swim four one-way 25-m trials in front crawl, attached to a tethered speedometer and filmed by cameras in the whole lap for validation. Based on the literature, several goal metrics were defined over speedometer data, each one representing the performance of the swimmer either in one phase (maximum velocity of wall push-off phase) or several phases (time of 15 meters for wall push-off, glide, stroke preparation phases). Following a macro-micro approach, the IMU parameters of each swimming phase were used to predict the goal metrics. The selected IMU parameters were in line with the characteristics of movement within each phase and can estimate the corresponding goal metric with an R2 over 0.8 and relative RMSE lower than 10%
AN INERTIAL SENSORS-BASED METHOD FOR PHASES AND EVENTS IDENTIFICATION IN PARA-ROWING: TOWARDS AN ON-WATER PERFORMANCE ASSESSMENT
Get PDFThe aim of this study is to propose and validate an inertial sensors-based methodology for the para-rowing stroke cycles segmentation. One non-disabled athlete performed two para-rowing set-ups, simulating PR1 (arms and shoulders-AS) and PR2 (trunk and arms-TA) conditions. Catch and finish events of each stroke cycle were identified on the signals measured by three sensors located on the right forearm (FA), upper arm (UA), and on the trunk (T). Accuracy was quantified by identifying the same events on the 3D trajectory of one right hand-located marker. UA and FA sensors data lead to a more accurate detection of stroke events with respect to the T sensor (average error: 28.8ms, 29.0ms, 56.9ms). The present results open promising scenarios on the application of inertial sensors in para-rowing for real-time performance-related feedback to athletes and coaches
THE EFFECTS OF EIGHT-WEEK SPORTS-SPECIFIC TRAINING ON THE KINEMATICS OF DOUBLE-POLE TECHNIQUES IN NOVICE CROSS-COUNTRY SKIERS
No full textThe purpose of the current study was to 1) investigate the effectiveness of an eight-week training specific to cross-country skiing on kinematic characteristics of the double-pole techniques in novice athletes; 2) examine the relationships between joint angles and poling kinematics during different phases of the double-pole in novice and experienced athletes. Ten novice cross-country skiing college athletes from China and nine experienced cross-country skiing college athletes from the United States participated in the eight-week cross-country skiing training. Three cameras were used to collect the kinematics of the double-pole techniques in field before and after the training for the novice athletes while only after the training for experienced skiers. The novice athletes showed significant increases in the speeds and traveled distances during the poling and gliding phases and the entire cycle (ppp
MEDIAL-LATERAL HIP POSITIONS PREDICTED KINETIC ASYMMETRIES DURING BILATERAL SQUATS IN COLLEGIATE ATHLETES FOLLOWING ACLR
Get PDFAnterior cruciate ligament (ACL) re-injury rates are high in collegiate athletes, and double-leg squats are commonly used following ACL reconstruction (ACLR). The purpose was to quantify the correlations between the medial-lateral shoulder/hip kinematics and bilateral kinetic asymmetries during double-leg squats in collegiate athletes at two assessments. Seventeen collegiate athletes performed three double-leg squats 0-6 months and/or 6-12 months following ACLR. Medial-lateral shoulder/hip positions and bending angles were calculated. Medial-lateral hip positions were significant and strongly correlated with ground reaction force and knee moment asymmetries. A commercially available camera may be used to capture the frontal plane motion as a low-cost and more convenient tool to monitor bilateral kinetic asymmetries during double-leg squats in patients following ACLR
AN INVESTIGATION INTO THE EFFECT OF LANE RADIUS ON STEP CHARACTERISITCS IN INDOOR BEND SPRINTING
Get PDFThe study aimed to identify the effect of radius on step characteristics during bend sprinting. Eight sprinters undertook two ~80 m sprints in two different conditions through two capture areas (straight and bend) collecting whole-body kinematic data. Step Velocity on the straight was lower than Lane 2 on the bend for the left-to-right step, brought about by a greater Step frequency (SF). Right-to-left SF was significantly lower in Lane 4 in comparison to the straight due to a greater step time. Step time was greater in Lane 4 for the right step compared to Lane 2. A greater SF was observed for the left step compared to the right step in Lane 4 whilst a greater flight time was seen for the left step in Lane 2. Therefore, lane radius typical of indoor competition elicits performance changes during bend sprinting, warrenting further biomechanical analysis
IDENTIFYING JOINT-SPECIFIC LIMITATIONS AND TARGETS FOR IMPROVING WEIGHTLIFTING PERFORMANCE
Get PDFThe purpose of this study was to determine the relative effort (RE) of the extensor and plantarflexor muscles during the pull phase of the clean. Five weightlifters performed the clean at 85% of their one-repetition maximum while motion capture and ground reaction forces were recorded and used to calculate lower body net joint moments via inverse dynamics (NJMID). Joint angle and angular velocity data were used as input to a musculoskeletal model that estimated maximum NJM (NJMmax) weightlifters could theoretically generate. The RE of the hip and knee extensor and ankle plantarflexor muscles were calculated as the ratios between NJMID and NJMmax. The results suggest that the knee extensor muscles operate close to max capacity during both pull phases, and that the plantarflexor muscles operate close to their max capacity during the second pull
HANDSTAND BALANCE MOTOR CONTROL MECHANISMS
Get PDFThe goal of a handstand, a fundamental skill in gymnastics, is to maintain a balanced stance by controlling center of mass (COM) position. Successful handstands predominantly use wrist torque to control the COM in the anterior-posterior (AP) plane. The aim of this study was to determine the underlying motor control mechanisms necessary to maintain a strong handstand stance through analysis of joint angle and COM position variability. Full body 3D kinematic data were collected on three competitive level gymnasts during 30 s floor handstands. Variability of joint angles were consistently higher than the center of mass, demonstrating that joints self-organize in a motor control strategy to produce torques in order to control the COM. Using multiple linear regression analysis, it was found that shoulder flexion/extension variability was the largest contributor to controlling the COM in both the medio-lateral (ML) and AP planes
AN INVESTIGATION INTO THE RELEASE FACTOR EFFECTS OF HAMMER THROW
Get PDFThis study aimed to determine the relationship of release factors on the final hammer throw distance of American throwers as well to determine where differences in release factors between the years and throw distance groups (TDG). The video from 94 hammer throws (52 female throws and 42 male throws) were analyzed using 2-D to 3-D coordinates via DLT procedures. Analysis of the release factors of a throw revealed correlations with release velocity but not height and angle. Further analysis revealed that release height has decreased while vertical velocity and release angle have increased since 2016
SUPPORT VECTOR MACHINES CAN CLASSIFY RUNNER’S ABILITY USING WEARABLE SENSOR DATA FROM A VARIETY OF ANATOMICAL LOCATIONS
Get PDFWe developed and tested an algorithm to automatically classify twenty runners as novice or experienced based on their technique. Linear accelerations and angular velocities collected from six common wearable sensor locations were used to train support vector machine classifiers. The model using input data from all six sensors achieved a classification accuracy of 98.5% (10 km/h running). The classification performance of models based on single sensor data showed a 56.3-94.5% accuracy range, with sensors from the upper body giving the best results. Comparisons of kinematic variables between the two populations confirmed significant differences in upper body biomechanics throughout the stride, thus showing applied potential when aiming to compare novice runner’s technique with movement patterns more akin to those with greater experience
AN AUTOMATED METHOD FOR THE ESTIMATE OF VERTICAL JUMP POWER THROUGH INERTIAL MEASUREMENT UNITS
Get PDFVertical jump performance analysis allows for assessing the ability of the lower limb to generate mechanical power. The analysis performed with inertial measurement units (IMUs) is affected by inertial effects of wobbling masses. To compensate for them, an automated method was developed to estimate peak and mean concentric power based on anthropometric and time-frequency features. IMU data of 47 countermovement- (CMJ) and 50 squat- jumps (SJ) performed by 17 participants were used. Force platform data were used to obtain reference power values. Features were chosen according to the best subset regression method, devising a multiple linear regression for each estimated power parameter and jump. The regressions explained 88% and 96% variation, for CMJ peak and average power respectively, while explaining 75% and 74% of the variation for the SJ