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DETECTION OF DIFFERENT THROW TYPES AND BALL VELOCITY WITH IMUs AND MACHINE LEARNING IN TEAM HANDBALL
Get PDFThe purpose of this study was to investigate if an inertial measurement unit (IMU) and machine learning could be used to detect different types of team handball throws and predict ball velocity. Throwing was measured using IMUs and a radar gun in seventeen participants during standing, running and jump throws with a circular and whip-like wind up. Using these data, machine learning could predict peak ball velocity with an error of 1.05 m/s and classify approach types and throw types with ~85–90% accuracy. It was concluded that to monitor throwing load, the combination of inertial measurement units and machine learning offers a practical and automated method of quantifying throw counts and discriminating throw types in handball players under standard conditions
COMPARISON OF CONCENTRIC MOVEMENT VELOCITY WITH PUSH BAND 2.0 AND VICON MOTION CAPTURE DURING RESISTANCE EXERCISES
Get PDFWe compared concentric movement velocity (CMV) measured with PUSH Bands (v.2.0) and a Vicon motion capture system (MC) during back squat (SQ) and bench press (BP) resistance exercises (RE) completed using a 2-dimensional smith machine. Twelve experienced resistance-trained males completed 10 repetitions at 50% of 1-repetiton maximum (1RM), and 6 repetitions at 75% 1RM for both BP and SQ. Use of Least-squares means contrasts suggests CMV measures did not differ between measurement technologies. Also, there is no indication of systematic bias between PUSH and MC. PUSH provides an accurate and reliable measurement of CMV during moderate and high intensity SQ and BP as compared with MC
ASSESSMENT OF KINEMATIC CMJ DATA USING A DEEP LEARNING ALGORITHM-BASED MARKERLESS MOTION CAPTURE SYSTEM
Get PDFThe purpose of this study was to compare the performance of a 2D video-based markerless motion capture system to a conventional marker-based approach during a counter movement jump (CMJ). Twenty-three healthy participants performed CMJ while data were collected simultaneously via a marker-based (Oqus) and a 2D video-based motion capture system (Miqus, both: Qualisys AB, Gothenburg, Sweden). The 2D video data was further processed using Theia3D (Theia Markerless Inc.), both sets of data were analysed concurrently in Visual3D (C-motion, Inc). Excellent agreement between systems with ICCs \u3e0.988 exists for Jump height (mean average error of 0.35 cm) and ankle and knee sagittal plane angles (RMS differences \u3c 5°). The hip joint showed highe
THE EFFECTS OF SYSTEMATIC UNLOADING ON MUSCLE ACTIVATION AND FATIGUE DURING RESISTANCE EXERCISE
Get PDFThis study examined acute, local muscle fatigue and recovery, temporally, during velocity-based resistance exercise. A dynamic single-leg extension resistance exercise model with systematic unloading based on changes in repetition velocity was used to measure changes in quadriceps muscle activation patterns. EMG indices of acute, local muscle fatigue and recovery were closely associated with changes in movement velocity for each unloading condition. Systematic Unloading (SU) is an effective resistance training protocol in order to minimize acute, local muscle fatigue and facilitate muscle fatigue recovery within a se
PEAK MAGNITUDES OF DYNAMIC KNEE JOINT LOADING ARE NOT INFLUENCED BY CUSTOMISED BODY SEGMENT PARAMETERS
Get PDFAlthough accurate body segment parameters (BSPs) do not appear to be important for peak joint moments recorded during walking, it is not clear whether joint moment magnitudes during highly dynamic activities can be modified when using individualised BSP data and having high frequency motion characteristics retained in the segmental acceleration data. Overall, it was found that BSPs had little influence on peak knee joint moment magnitudes during 45°cutting, drop jumping and fast running (even with high frequency signal components (up to 30 Hz) present in the dataset). This supports previous walking gait research that suggests BSPs have only a small effect on knee joint moment calculations
IT NECESSARY TO NORMALIZE JUMP TEST RESULTS TO ANTHROPOMETRIC PARAMETERS?
Get PDFThe purpose of the present study was to analyse the relationship of different normalization methods in the jump performance, obtained from a digital application (My Jump 2 ®). 189 young women made up the sample. Each of them had to perform three attempts of a bilateral countermovement jump (CMJ) in front of a mobile device. The jump height (JH) and power (P) were the main results, which were processed to normalize them. The JH was normalized to height (JH/H) and to leg length (JH/LL). P was normalized to body mass (RP), while force values were divided by the time of jump to get the Explosive Index of Strength (EIS). The results showed a good association and poor prediction between the variables JH and P, not so between JH and EIS, where no significant relationship was observed. However, a strong relationship was observed between JH / LL and RP (r = 0.801; r2 = 0.641; p
KEYWORDS: Smartphone app, vertical jump, biomechanics
AN IMPROVED CYCLING HELMET TECHNOLOGY TO MITIGATE HEAD INJURIES
Get PDFThis study examined the extent to which cycling helmet paddings made of thermoplastic polyurethane (TPU) material mitigated impact accelerations in a cycling helmet to reduce the likelihood of concussions. The results of this study indicate that the TPU paddings mitigate peak linear acceleration between 8.37% and 25.48%, and reduce the risk of head injury, as measured by the Gadd Severity Index (GSI) scores, ranging 20.97% to 27.62% across helmet impact locations. This information becomes useful for researchers, cyclist and helmet designers because it provides an avenue to improve cycling helmet capabilities in minimizing the risk of traumatic brain injuries due to a head impact
DOES VARIABILITY PLAY A ROLE IN HAMSTRING STRAIN INJURIES? A PILOT STUDY IN SPRINTING
Get PDFA scaled OpenSim model was used to assess the variability and changes in muscle loads across multiple strides and at different running speeds (2-8 m·s-1). Peak biceps femoris muscle fibre force, length, velocity and power occurred during the late swing phase of running and became more variable above 6 m·s-1. With each increase in running speed from 2-8 m·s-1, peak force occurred earlier in the swing, at longer muscle lengths and became less variable in its timing.Changes in variability can create a greater risk of injury and exploring these trends further may provide additional insight into hamstring strain injuries
EXPLORING THE RIGHT SPOT: HOW MUCH INFORMATION REALLY TO EXPLORE FOR EFFICIENT CLIMBING?
Get PDFThe purpose of this study was to investigate the optimal amount of information to explore by a climber to effectively anticipate the next actions and therefore ensure efficiency during the climb. Climbers (N=6), with mean age 15.6 years (+/-1.6) were assigned based on their maximal performance to an “expert” group (N=3 who can climb a route with difficulty level 7 or more) and a “beginner” group (N=3 who can climb a route with difficulty level 5c maximum). All those 6 climbers practiced 6 times not identical but similar routes (same difficulty level and technical requirements), but the number of visible holds was decreased trial after trial. In other words, during the first trial the next 6 holds were visible (the holds lights on as far as the climber actually climbs up), the second trial showed only the 5 next holds, the third trial showed only the next 4 holds, etc… Both the performance, efficiency and exploratory activity were measured during the ascent. Results showed that a major drop in performance arose for experts when they went through the condition with 3 visible holds to the condition with only 2 visible holds, showing that expert climbers can ensure fluidity of their climb by anticipating in the next 3 holds. Concerning the beginners, no drop in performance were observed, advocating for a lack of anticipation for the beginners, as they mainly use the next hold to anticipate (or rather “not anticipate”)
LOWER LIMB JOINT COORDINATION STRATEGIES OF 5-7 AND 9-11-YEAR-OLD CHILDREN ON DOMESTIC TRAMPOLINES OF DIFFERENT STIFFNESSES
Get PDFThe aim of this research was to assess differences in lower limb coordination in two developing age groups during trampoline bouncing, and if alterations in trampoline stiffness influence coordination strategies in children. Eighteen participants were recruited and grouped based on age; 5-7 and 9-11 years old. Each participant performed twenty bounces on two different trampolines of high and low stiffness. Lower limb kinematics were recorded using 3D motion capture and analysed across ten middle bounces for each trampoline. Findings demonstrated that the two different age groups employed different coordination strategies, with some changes with different trampoline stiffnesses. This information could be useful for trampoline manufacturers to modify trampolines for age-specific trampoline use