Kinetic and Kinematic Characteristics of Proficient and Non-Proficient 2-Point and 3-Point Basketball Shooters

The purpose of this study was to examine kinetic and kinematic characteristics of various types of 2-point and 3-point basketball shooting approaches and determine which variables have the greatest contribution in discriminating proficient (PRO) from non-proficient (N-PRO) shooters. While standing on a force plate, twenty-nine recreationally active males performed a total of 1740 shots by utilizing stationary and step-in shooting approaches. Two high-definition cameras were used to simultaneously capture kinematic parameters of shooting motions. The type of shooting approach showed as a non-influential factor. During the preparatory phase of the shooting motion, PRO 2-point shooters demonstrated higher elbow and basketball height placements, greater flexion in the shoulder and elbow joints while attaining greater release and entry ball angles during the release phase. PRO 3-point shooters demonstrated greater elbow flexion, higher basketball placement, and less hip flexion during the preparatory phase while attaining greater heel, release, and trajectory heights during the release phase. When entered into a full-model discriminant function analysis, elbow angle, elbow height, and release angle variables correctly classified PRO from N-PRO 2-point shooters in 62.1% of cases and hip angle, heel height, and elbow angle variables correctly classified PRO from N-PRO 3-point shooters in 81.6% of cases.

The impact of walker height positions and their influence on triceps activity and energy conservation: a pilot study

Background/Aims Millions of adults use walkers for functional mobility. Inappropriate walker use is associated with incorrect height, forward-leaning posture, and increased energy expenditure. Few studies have investigated the impact of walker positions and their influence on triceps activity. The present study assessed walker height and baseline positioning for individuals with a 50% weight bearing restriction of the lower extremity, and implications for energy conservation. Methods A total of 38 young adults (mean age = 24.95 years; 84.2% female; 15.8% male) participated in this study with a two-wheeled walker. Participants executed five walker positions while maintaining 50% weight bearing of the lower extremity to determine the effect on triceps electromyography activity. Results Triceps electromyography activity did significantly change across the five walker positions assessed (X2 [df=37, P<0.001]). This study showed that the median electromyography activity for positions B (median=0.268) and A (median=0.280) was significantly less than the median electromyography activity for position E (median=0.452; P<0.001). The effect sizes for comparisons of positions B and E (r=0.49) as well as A and E were the largest (r=0.53). Conclusions These findings suggest an elbow angle of 26–35° (position B), followed by an elbow angle of 15–25° (position A), with the walker in line with the heels of the participant, to be superior in minimising exertion of the triceps.

An Experimental Study of the Influence of Hand-Arm Posture and Grip Force on the Mechanical Impedance of Hand-Arm System

In order to investigate the effects of hand-arm posture, grip force, push force, and vibration excitation intensity on the mechanical impedance of human hand-arm system, a test system with a self-developed vibration handle has been prepared. Based on the testing system, the mechanical impedance of the hand-arm system of seven Chinese adult males were tested and calculated under the random vibration excitation with the frequency of 10–1000 Hz. The results reveal that when the frequency is lower (<40 Hz), the hand-arm system with an elbow angle of 180o produces a higher mechanical impedance; when the frequency ranges from 40 Hz to 100 Hz, the hand-arm system with an elbow angle of 90o generates a higher mechanical impedance; while when the frequency is higher (>100 Hz), the hand-arm posture seems to have no obvious effect on the mechanical impedance. Higher grip or push force would increase the frequency corresponding to the peak value of the mechanical impedance and often correspond to a higher mechanical impedance in a specific frequency range (30–200 Hz). When the frequency is lower (<140 Hz), vibration intensity has certain effects on the mechanical impedance of the hand-arm system. In conclusion, vibration intensity does not directly affect the mechanical impedance, but an increase in grip or push force often causes an increase in mechanical impedance and a higher frequency that corresponds to the peak of mechanical impedance.

Manipulation of task constraints on throwing of amateur handball athletes

BACKGROUND: In handball, speed and accuracy are essential characteristics for the performance of throwing. AIM: To verify the effects of manipulation of task constraints during the throws on kinematic variables in amateur handball players. METHOD: 18 amateur handball players (18-27 years) made 10 throws to the target with a focus on speed and 10 throws with a focus on accuracy. The kinematic analysis of the throwing was performed, and the Student's t-test was used. RESULTS: Greater velocity, and hand, acromion, and iliac spines trajectories for throws with a focus on speed in cocking phase was observed. During the acceleration phase, there was greater velocity, and trajectory of the right upper posterior iliac spine, and less time and hand, acromion, and left upper posterior iliac spines trajectories for throws with a focus on speed. The throw with a focus on speed showed greater shoulder and elbow angles at the beginning, and greater elbow angle at the end of throwing. CONCLUSION: The manipulation in the focus of the throw influenced the movement strategy from the cocking phase to the acceleration phase according to the movement intentionality, with most of the variables presenting greater values in the throw with a focus on speed.

Radiographic Determination of the Canine Elbow Joint Angle in Collimated Views

The mediolateral flexed, extended, or neutral elbow radiographic views are commonly used in clinical practice. However, there is currently no standardized methodology to accurately measure the elbow joint angle in mediolateral images that include only the elbow joint and surrounding tissues. The main aim of this work is to compare elbow joint angles obtained from mediolateral radiographs that include the complete arm and forearm of the dog, with angles measured in radiographs including only the elbow. Ninety mediolateral views of elbow joints were obtained from 50 canine thoracic limbs, with 39 joints <90º, 30 ≥90 - ≤120º and 21 >120º. Radiographs were centered on the elbow joint and include the shoulder and carpal joints. For each complete forelimb radiographic image, the elbow angle was measured using the methodology described in previous studies. Then, the digital images were cut to obtain only the joint and surrounding tissues, establishing a new set of anatomical landmarks to measure the joint angles: the lateral humeral epicondyle was used as an angular point, with the linking points being the nutritional orifice of the radius at the antebrachial interosseous space and the intersection point of the lateral supracondylar crest with the cranial humeral endosteum. There was a good agreement observed between the two elbow angle measurement methodologies. The intraclass correlation coefficient was statistically significant, with the lower limits of the 95% confidence interval (CI) at >0.75, and with zero being included in the standard error of the mean 95% confidence interval in the Bland-Altman test. This elbow angle measurement methodology based on anatomic landmarks next to the elbow joint is accurate and may be used for clinical and research purposes.

Abstract P202: Estimation of Arm Kinematics in Stroke Survivors With Wearable Sensors

Introduction: Stroke is the leading cause of long-term disability in the US, often resulting in upper extremity (UE) motor impairment. Numerous clinical metrics have been developed and used to evaluate UE motor function to assess rehabilitation outcomes, but most of these are innately subjective and/or have relatively low sensitivity to change due to the use of ordinal scales. As a result, there is a growing interest in the use of kinematics to evaluate UE motor function, as they provide completely objective, high resolution quantitative measurements. However, obtaining kinematic measurements in stroke survivors can be a challenging task, as non-ideal environments (e.g., hospital rooms), expense, and a limited ability to perform calibration poses can make traditional optical tracking systems impractical. To overcome these challenges, we developed and compared two methods using different wearable sensors to estimate elbow angle and wrist position during reaching movements in people with stroke. Methods: We developed frameworks specific for two different types of sensors, inertial measurement units (IMU) and virtual reality (Vive) trackers, to estimate elbow angle and wrist position. We assessed each sensor’s estimation accuracy during pure flexion-extension motion, performed by a manual goniometer, and pure pronation-supination motion, performed by a healthy participant. We also compared each sensor’s ability to longitudinally track a stroke survivor’s UE function by using the wrist position estimates to compute sweep areas during a sweeping task. Results: For the IMUs, our results demonstrated accuracy to within 4.8° and 1.2 cm for elbow angle and wrist position, respectively. For the Vive, our results demonstrated accuracy to within 2.2° and 0.9 cm. The change in sweep area estimated by each method agreed with each other, as the difference between estimates was approximately 4% of the change in sweep area. Conclusion: These methods can be used to develop and accurately assess kinematic metrics for use in evaluating stroke rehabilitation outcomes.

Surprisingly Fast Interface and Elbow Angle Dynamics of Antigen-Binding Fragments

Fab consist of a heavy and light chain and can be subdivided into a variable (VH and VL) and a constant region (CH1 and CL). The variable region contains the complementarity-determining region (CDR), which is formed by six hypervariable loops, shaping the antigen binding site, the paratope. Apart from the CDR loops, both the elbow angle and the relative interdomain orientations of the VH–VL and the CH1–CL domains influence the shape of the paratope. Thus, characterization of the interface and elbow angle dynamics is essential to antigen specificity. We studied nine antigen-binding fragments (Fab) to investigate the influence of affinity maturation, antibody humanization, and different light-chain types on the interface and elbow angle dynamics. While the CDR loops reveal conformational transitions in the micro-to-millisecond timescale, both the interface and elbow angle dynamics occur on the low nanosecond timescale. Upon affinity maturation, we observe a substantial rigidification of the VH and VL interdomain and elbow-angle flexibility, reflected in a narrower and more distinct distribution. Antibody humanization describes the process of grafting non-human CDR loops onto a representative human framework. As the antibody framework changes upon humanization, we investigated if both the interface and the elbow angle distributions are changed or shifted. The results clearly showed a substantial shift in the relative VH–VL distributions upon antibody humanization, indicating that different frameworks favor distinct interface orientations. Additionally, the interface and elbow angle dynamics of five antibody fragments with different light-chain types are included, because of their strong differences in elbow angles. For these five examples, we clearly see a high variability and flexibility in both interface and elbow angle dynamics, highlighting the fact that Fab interface orientations and elbow angles interconvert between each other in the low nanosecond timescale. Understanding how the relative interdomain orientations and the elbow angle influence antigen specificity, affinity, and stability has broad implications in the field of antibody modeling and engineering.