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RELATIONSHIP BETWEEN KINEMATIC CHARACTERISTICS AND FREE-THROW SHOOTING PRECISION: MARKERLESS MOTION CAPTURE ANALYSIS
Get PDFThe search for aspects of basketball shooting that characterize successful performance is an area of focus for sports biomechanists. However, the systematic evaluation of these key elements during shooting practice is limited due to the time it takes to collect and/or process the data. Thus, the purpose of the present study was to evaluate the relationship between some of the key kinematic variables extracted from a markerless motion capture system on free-throw shot performance. Multivariable linear regression analysis indicated that shot plane alignment, trunk rotation, entry angle, and timing of elbow extension were some of the key contributors to free-throw shot precision. Overall, these kinematic variables serve as a preliminary set of outcomes that can be reported to coaches and players that decide to use markerless motion capture technology for free-throw shooting biomechanical analysis
TWO AND THREE-DIMENSIONAL ASSESSMENTS OF LOWER-LIMB KINEMATICS IN UNDERWATER FLY KICK
Get PDFThe purpose of this study was to compare sagittal plane lower limb kinematics of underwater fly kick measured using two and three-dimensional methods. Eight male participants (average FINA points score 801±138) completed underwater fly kick trials, recorded using a six camera Qualisys underwater system. Each trial was analysed using both two and three-dimensional methods. Lower-limb angles were significantly underestimated using two-dimensional methods, particularly at the hip where flexion and range of motion reduced by 13.73 degrees and 15.91 degrees respectively. The ankle and hip produce a large amount motion in the transverse and frontal planes. The results of two-dimensional analyses of underwater fly kick should be interpreted with caution due reductions in measured angles, and exclusion of out-of-plane kinematic information
EVALUATING THE INFLUENCE OF KNEE JOINT ANGLE ON MAXIMUM ISOMETRIC BELT SQUAT PERFORMANCE
Get PDFBelt squat testing measures maximum upward isometric force from the lower extremities using a ground-tethered belt around the waist. A lack of standardized body positioning during isometric belt squat testing can lead to inconsistent test results. We aimed to evaluate the influence of sagittal knee joint angles on maximum isometric belt squat performance. Thirty-three healthy volunteers (24 female) performed one maximal effort belt squat at five randomly ordered sagittal knee joint angle ranges: (1) 80-100°, (2) 100-120°, (3) 120-140°, (4) 140-160°, and (5) 160-180°. Sagittal knee joint angles between 120-140° and 140-160° led to greater maximum vertical ground reaction forces compared to each other condition (p £ 0.017). Our results provide a starting point to establish best-practices for assessing lower limb strength during maximum isometric belt squat testing
THE EFFECTS OF RUNNING VELOCITY AND LOWER EXTREMITY LOADING ON BIARTICULAR LEG MUSCLES DURING TREADMILL RUNNING
Get PDFThe purpose of this study was to investigate the changes in muscle activity levels in treadmill running while using wearable resistance as a function of running speed. Nine recreational runners participated in this study; they were requested to perform the running without and with wearable resistance at four discrete speeds ranging from 2.5 to 7.0 m/s on a treadmill. The mass of wearable resistance was set at one third of each participant’s shank and foot mass. Repeated-measures two-way ANOVA analysis was then used to explore the effect of loaded and speed. The data showed that shank loading enlarged the activation amplitude of the biceps femoris (BF) for the concentric action of hip extension following the stretch of knee extension at a high running speed. The loaded condition facilitated the rectus femoris (RF) to be stretched
Prosopis velutina Response to Aerial Herbicide Application
Get PDFHerbicides have been widely used to manage woody vegetation, but quantification of their effects is often lacking. We documented the impacts of a commonly used clopyralid + aminopyralid + triclopyr herbicide blend on Prosopis velutina Woot. in grazed Sonoran Desert grasslands in southern Arizona. Similar to other applications of comparable herbicide blends in the region, we recorded only modest and short-term impacts. P. velutina mortality was 7%. Foliar cover declined to 9.2% ± 0.80% the month following treatment and was comparable across size classes. Cover reductions persisted for ∼2 yr, by which time it was comparable on treated and control plants (66.9% and 69.3%, respectively). On the basis of eddy covariance tower monitoring of carbon and water flux, soil temperature, and soil moisture, we suggest how knowledge of diurnal and seasonal changes in physiological activity (e.g., evapotranspiration, gross primary production) and environmental conditions may help identify more optimal times to apply herbicides to improve their efficacy. Future research should explore P. velutina response to herbicides at various levels of photosynthetic activity in response to soil temperature and soil moisture in the subtropical North American Monsoon climate system of the Sonoran Desert. From a broader ecosystems trophic perspective, our results also suggest a need to ascertain how herbicide-induced reductions in P. velutina pod and seed production may impact native herbivore communities
BALL SIZE AND WEIGHT EFFECTS ON THROWING KINEMATICS AND KINETICS IN YOUTH BASEBALL ATHLETES
Get PDFIn baseball, youth players play on smaller fields with shorter base path distance, pitching distance, and smaller mounds. Despite this, the baseball itself remains unchanged for youth athletes. This prospective cohort analyzed the kinematics and kinetics of 38 youth baseball pitchers while using modified sized and weighted baseballs. An ANOVA was used to determine statistical significance amongst ball modifications. ANOVA results show significance between the 3oz-5oz baseball with the 3oz baseball decreasing elbow varus torque. This is a preliminary study on the effects of modified baseballs on youth athletes
CHANGES IN BACK SQUAT BAR VELOCITY AND PERCEIVED MUSCLE SORENESS FOLLOWING A STANDARDISED RUGBY LEAGUE MATCH SIMULATION
Get PDFThis study examined changes in back squat bar velocity and perceived muscle soreness following a rugby league match simulation protocol. Twenty male rugby league players (age: 19.8 ± 0.7 yrs) were recruited for this study. Back squat bar velocity and perceived muscle soreness of the lower body were collected on four days surrounding a match simulation: -24 h (prior to match simulation), +0 h (after the match simulation), +24 h and +48 h. Compared to baseline (-24h), there were non-significant decreases in maximum (dz=-0.50, moderate) back squat bar velocity +0 h. There was a significant increase in perceived muscle soreness at +0h only (p=0.003). Results suggest that elevated muscle soreness may not indicate impaired neuromuscular performance and highlight the importance of monitoring fatigue via multiple measures to ensure appropriate coaching decisions are made
ESTIMATION OF GROUND REACTION FORCE DURING RUNNING USING CONSUMER-LEVEL WEARABLE INSOLES AND MACHINE LEARNING
Get PDFData from NURVV Run, a consumer-level wearable technology product, embedding pressure insoles and inertial transducers, were used as an input into a deep learning model for the estimation of vertical ground reaction forces (vGRF) during running. Force data were collected from an instrumented treadmill during a running protocol of mixed gradients and speeds, serving as the gold standard to evaluate the model accuracy. Mean difference in peak vGRF was 0.36 ± 0.26 BW across participants and mean root mean squared error was 0.27 ± 0.15 BW. Model accuracy varied considerably between participants; it would be expected that a larger dataset with a greater variety of input variables would improve on this. A future version of this model could allow continual assessment of load accumulation during distance running, helping identify early signs of elevated injury risk
INVESTIGATING DRILL CONSTRAINT KINEMATICS IN MALE BASEBALL PITCHERS USING MARKERLESS MOTION CAPTURE
Get PDFThis study investigated the kinematic differences that pitching constraint drills elicit compared to a baseball pitch. 18 male baseball pitchers with average height (183.7 ± 5.2cm), weight (87.4 ± 9.6kg), and skill level (Professional (4), Collegiate (5), High School (9)) were included. Video was recorded using a single camera from the open side. Each pitcher threw 3 maximum effort pitches from a mound. Next, 3 maximum effort throws were recorded for 8 different throwing drills: medicine ball hook’em drill, pivot pickoff drill, foot-up rocker drill, walk-in drill, towel drill, janitor drill, drop-step drill, and long toss. Videos were processed using pitchAITM, a markerless motion capture solution. The medicine ball hook’em drill was the most different to a pitch, and the towel drill was the most similar. This work demonstrates the first collective approach to studying the biomechanics of frequently used baseball pitching constraint drills
FORCE PROFILE OF FUNCTIONAL LEG MUSCLE GROUPS IN CURVE SPRINTING - PRELIMINARY RESULTS
Get PDFResearch on lower extremity joint and muscle kinetics in athletic curve sprinting is under-represented in the scientific literature. This is an issue due to its importance for training and rehabilitation protocols as well as for injury prevention. In this study, we analysed six male sprinters regarding their force profile of functional lower extremity muscle groups in curve sprinting. Three-dimensional motion capture (Vicon) and four force plates (Kistler) were used to capture kinematic and kinetic data. Inverse dynamic calculations (Anybody), including muscle forces, provide first insights into potential side differences of leg muscle group force profiles between the inside and the outside leg in submaximal curve sprinting (9.48 ± 0.26 m/s). However, a differentiated analysis of individual muscles is necessary in the future as grouping might overlay the side-specific effects in particular muscles