Radar Gun Research Articles

Effects of Repetitive Pitching on Trunk Muscle Endurance and Thoracic and Shoulder Kinematics.

Baseball players are aware of the potential of shoulder problems due to repetitive throwing. However, few studies have examined how pitching repeatedly affects the thoracic spine and shoulder. This study aimed to determine the effects of pitching repeatedly on the endurance of trunk muscles and kinematics of the thoracic spine and shoulder. Cohort study. Trunk muscle endurance was assessed in flexion, extension, and lateral flexion positions in 12 healthy amateur baseball players. The positions of stride foot contact (SFC) during the early cocking phase and maximal shoulder external rotation (MER) during the late cocking phase were used to compute the thoracic and shoulder kinematics in degrees. Participants were then asked to throw 135 fastballs (~9 innings with 15 throws per inning). Throwing motions were monitored throughout the first, seventh, eighth, and nine innings, whereas trunk muscular endurance was assessed before and after the repetitive throwing activity. Ball speed during pitching was measured using a radar gun. All outcome measures were statistically compared to examine differences over time. The trunk muscle endurance declined after the throwing task. In the eighth inning, compared with the first inning, the thoracic rotation angle at the SFC increased toward the throwing side. In contrast, the shoulder horizontal adduction angle at MER decreased in the seventh and ninth innings. With repeated pitching, trunk muscle endurance gradually declines, and repetitive throwing significantly altered kinematics of the thoracic rotation at SFC and shoulder horizontal plane at MER. 2a.

Managing Accident Prevention in Ski Resorts: Participants’ Actual Velocities in Slow Zones

Velocity is one of the main factors affecting the kinematic of snow sports' accidents and the severity of resulting injuries. The aims of the present study were to measure the actual maximum velocities attained by a sample of snow sports participants in slow zones, to compare them to the recommended velocity limits and to assess whether their velocities were in any way related to their personal characteristics and to environmental conditions. Data were drawn from a sample of 1023 recreational skiers and snowboarders during the 2021-2022 winter season at four ski resorts located in the Spanish Pyrenees. Maximum velocity measurements were taken by the authors with a radar speed gun whose precision had been previously validated. Bivariate analysis tests were used to compare the influence that personal characteristics and environmental conditions had on the participants' maximum velocities. Furthermore, a multivariate analysis was performed. The binary logistic regression was used to distinguish the categories of personal and environmental factors that have the highest probabilities of impact on different segments of velocity. As generally accepted, probability values were two-tailed, and values of 0.05 or less were regarded as statistically significant. Participants' mean measured maximum velocity (±SD) was 51.61 (±16.14) km/h. A vast majority of the participants in this study traveled in slow zones at actual maximum velocities well over the recommended limits. Multivariate analysis showed that modality and both environmental conditions (visibility and snow quality) were highly significant and can be used to explain the chances of an increase in velocity in slow zones. Further research is needed to investigate causal relationships between skiers and snowboarders' accidents, injuries and disrespect for velocity limits.

The effect of a combined sprint training intervention on sprint force-velocity characteristics in junior Australian football players.

Sprint performance in junior Australian football (AF) players has been shown to be a differentiating quality in ability level therefore developing sprint characteristics via sprint-specific training methods is an important aspect of their physical development. Assisted sprint training is one training method used to enhance sprint performance yet limited information exists on its effect on sprint force-velocity characteristics. Therefore, the main aim of this study was to determine the influence of a combined sprint training intervention using assisted and maximal sprint training methods on mechanical characteristics and sprint performance in junior Australian football players. Upon completing familiarization and pre-testing, twenty-two male junior Australian football (AF) players (age 14.4±0.3 years, body mass 58.5 ±10.0 kg, and height 1.74 ±0.08 m) were divided into a combined sprint training (CST) group (n = 14), and a maximal sprint training (MST) group (n = 8) based on initial sprint performance over 20-meters. Sprint performance was assessed during maximal 20-meter sprint efforts via a radar gun (36 Hz), with velocity-time data used to derive force-velocity characteristics and split times. All subjects then completed a 7-week in-season training intervention consisting of maximal sprinting (MST & CST groups) and assisted sprinting (CST only), along with their usual football specific exercises. Moderate to large pre-post within group effects (-0.65 ≤ ES ≥ 0.82. p≤0.01) in the CST group for relative theoretical maximal force (F0) and power (Pmax) were reflected in improved sprint performance from 0-20 m, thereby creating a more force-oriented F-v profile. The MST group displayed statistically significant pre-post differences in sprint performance between 10-20 m only (ES = 0.18, p=0.04). Moderate to high relative reliability was achieved across all sprint variables (ICC = 0.65-0.91), except for the force-velocity slope (SFV) and decrement in ratio of forces (DRF) which reported poor reliability (ICC = 0.41-0.44), while the CST group exceeded the pre-post minimal detectable change (MDC) in most sprint variables suggesting a 'true change' in performance across the intervention. It is concluded that implementing a short-term, combined sprint training intervention consisting of assisted and maximal sprint training methods may enhance sprint mechanical characteristics and sprint performance to 20-meters in junior AF players.

Design of Optical Collimator System for Vehicle Speed Gun using Non-Imaging Optics

Vehicle speed guns are usually used in normal sunlight conditions (daytime). If we want to use vehicle speed guns in low light conditions (nighttime), the illuminator is needed to provide sufficient light for the vehicle speed gun to take photos. The illuminator must fulfill two requirements: (i) using the infrared wavelength to ensure that the driver is not startled by dazzling eyes by the illuminator of the proposed speed gun system and (ii) high energy efficiency to make the illuminator compact leading to the use a small battery system to improve the portable of the proposed vehicle speed gun. In this study, an illuminator using a collimator system designed by using non-imaging optics is introduced. LEDs with infrared wavelength are chosen from the library of LightToolsTM, the structure of collimated is designed to transfer the illumination from the LEDs array to a square area of 3x3 m2 to cover the vehicle to detect the vehicle number plate. The design process is built based on the conservation of optical path length in the Matlab program. After that, the designed collimator is simulated in LightToolsTM software. The promising results of the simulation in LightToolsTM show that the collimator can efficiently transfer light from the LED array to the target area with a uniformity of about 70 % and optical efficiency of about 80 %.

A Roadside and Cloud-Based Vehicular Communications Framework for the Provision of C-ITS Services

Road infrastructure plays a critical role in the support and development of the Cooperative Intelligent Transport Systems (C-ITS) paradigm. Roadside Units (RSUs), equipped with vehicular communication capabilities, traffic radars, cameras, and other sensors, can provide a multitude of vehicular services and enhance the cooperative perception of vehicles on the road, leading to increased road safety and traffic efficiency. Moreover, the central C-ITS system responsible for overseeing the road traffic and infrastructure, such as the RSUs, needs an efficient way of collecting and disseminating important information to road users. Warnings of accidents or other dangers, and other types of vehicular services such as Electronic Toll Collection (ETC), are examples of the types of information that the central C-ITS system is responsible for disseminating. To remedy these issues, we present the design of an implemented roadside and cloud architecture for the support of C-ITS services. With the main objectives of managing Vehicle-to-Everything (V2X) communication units and network messages of a public authority or motorway operator acting as a central C-ITS system, the proposed architecture was developed for different mobility testbeds in Portugal, under the scope of the STEROID research project and the pan-European Connected Roads (C-Roads) initiative. RSUs, equipped with ETSI ITS-G5 communications, are deployed with a cellular link or fiber optics connection for remote control and configuration. These are connected to a cloud Message Queuing Telemetry Transport (MQTT) broker where communication is based on a geographical tiling scheme, which allows the selection of the appropriate coverage areas for the dissemination of C-ITS messages. The architecture is deployed in the field, on several Portuguese motorways, where road traffic and infrastructure are monitored through a C-ITS platform with visualization and event reporting capabilities. The provided architecture is independent of the underlying communication technology and can be easily adapted in the future to support Cellular-V2X (PC5 interface) or 5G RSUs. Performance results of the deployed architecture are provided.

Survey of Innovative Techniques for Speed Measurement of Vehicles

Advanced technology offers various alternatives for the speed measurement of vehicles. However, different technologies often result in different accuracy in the speed measurement of the vehicle. Lack of knowledge of accuracy between different technologies is a common problem for the researcher. This paper discusses the different techniques for speed measurement of vehicle-based on the theoretical study. One of the primary reasons for measuring speed is to enforce traffic speed laws and promote road safety. Speed limits are set to ensure that vehicles are travelling at safe speeds, given the conditions of the road, weather, and traffic. The use of speed measuring devices such as radar guns, laser guns, and speed cameras allows law enforcement agencies to monitor traffic and identify vehicles that are exceeding the speed limit. This information can then be used to issue citations or warnings to drivers, and ultimately to reduce the number of speed-related accidents and improve road safety. Various speed measurement techniques are included such as. RADAR (Radio Detection and Ranging) - this is one of the most common speed measurement techniques and uses radio waves to determine the speed of a vehicle, GPS (Global Positioning System) - GPS uses satellite technology to determine the location and speed of a vehicle. The MIRROR system uses multiple radar units to determine the speed of a vehicle, LIDAR (Light Detection and Ranging) - this technique gauges a vehicle's speed using lasers. The Speed Detection Camera System (SDCS) measures a vehicle's speed using cameras and image processing methods. On the highway, video streams are employed in image processing techniques to calculate the speed of the car.

Investigating the kinetics of repeated sprint ability in national level adolescent hockey players

ABSTRACT Repeated sprint ability (RSA) is more closely related to match performance outcomes than single-sprint performance, but the kinetic determinants in youth athletes remain poorly understood. Therefore, the aim of the study was to explore the kinetic determinants of RSA in youth athletes. Twenty trained adolescents (15 girls; 14.4 ± 1.0 years) completed five 15 m repetitions interspersed with 5-s rest. Velocity was measured during each trial using a radar gun at >46 Hz, following which the force–velocity–power (F-v-P) profile was fitted to a velocity–time curve and instantaneous power and force variables calculated. The mechanical efficiency of force application (DRF) was the primary predictor of both single and repeated sprint performance in adolescents. Secondly, hierarchical analyses revealed the percentage reduction in peak velocity, DRF, and allometrically scaled peak force explained 91.5% of the variance in 15 m sprint time from sprints 1–5. Finally, declines in allometrically scaled peak power were more closely related to declines in peak force than reductions in velocity. In conclusion, given DRF was the primary predictor of both single and repeated sprint performance training programmes targeting RSA need to include technique, and skill acquisition, components.

Development of a relation between traffic variables and environmental noise descriptors for four-lane National Highways

In India, transportation sector is quickly expanding. The heterogeneity of traffic plays a vital role in shaping noise ambience in vicinity of highways. This study aims to evaluate the factors that contribute to traffic noise along four-lane divided National Highways. Data were collected at 4 locations with free-flowing traffic on the National Highway 334 in India. The parameters included traffic noise levels, classified traffic volumes, vehicular speed, and geometry of highway cross-section. Traffic volume and composition were captured using videography, while traffic speed was measured using radar gun. Single octave spectral characteristics of the traffic noise were measured using a multi-channel noise spectrum analyser. The data was sampled at 15 minutes intervals and measurements carried out for 3-hour duration during peak and off-peak periods weekdays and weekends. Noise descriptors such as equivalent noise level (Leq), 10 percentile sound level (L10), 50 percentile sound level (L50), 90 percentile sound level (L90) were estimated from the measured data. Effect of traffic characteristics on the traffic noise levels was established through regression analysis. The study concludes that traffic volume, percentage of heavy vehicles, and traffic speed are the major factors influencing noise levels.

Concurrent Validity and Reliability of Different Technologies for Sprint-Derived Horizontal Force-Velocity-Power Profiling.

Cormier, P, Tsai, M-C, Meylan, C, Agar-Newman, D, Epp-Stobbe, A, Kalthoff, Z, and Klimstra, M. Concurrent validity and reliability of different technologies for sprint-derived horizontal force-velocity-power profiling. J Strength Cond Res 37(6): 1298-1305, 2023-This study evaluated the validity and reliability of common systems to assess sprint-derived horizontal force-velocity-power ( FVPH ) profile metrics. Two double constellation athlete monitoring systems (STATSports Apex, Catapult Vector S7) and one timing gate system were compared with a radar gun for the computation of FVPH metrics. Intersystem validity was assessed using intraclass correlation coefficients (ICC), Pearson's correlation coefficients ( R2 ), and Bland-Altman plots with absolute and percent agreement. Intrasystem reliability was assessed with agreement bias and ICC. STATSports demonstrated moderate agreement for F0 , Pmax , τ, and Drf (8.62, 6.46, -9.81, and 9.96%, respectively) and good agreement for V0 and MSS (-2.18 and -1.62%). Catapult displayed good agreement across all metrics ( F0 , V0 , Pmax , MSS, τ, and Drf : -0.96, -0.89, -1.85, -0.84, 0.38, and -0.27%, respectively). Timing gates demonstrated good agreement with V0 and MSS (-2.62 and -1.71%) and poor agreement with F0 , Pmax , τ, and Drf (19.17, 16.64, -20.49, and 20.18%, respectively). Intrasystem reliability demonstrated good agreement (<2% bias) with very large to near-perfect ICC (0.84-0.99) for Catapult and STATSports systems. Overall, GPS/GNSS 10 Hz technology is reliable across devices and can provide moderate-to-good accuracy of FVPH metrics in single maximal effort sprints. However, Catapult provided better agreement for more FVPH metrics than STATSports, which may be related to differences in proprietary algorithms. Also, modeling timing gate data using current FVPH profiling techniques results in poor bias that requires greater investigation. GPS/GNSS data can be used for FVPH profiling, which could inform performance and rehabilitation processes.

Changes in Elbow Stress and Ball Velocity During Reduced Effort Pitching: A Marker-Based Motion Capture Analysis

Background: Baseball pitchers often participate in throwing programs that involve throwing at reduced effort levels to gradually increase the amount of stress experienced across the elbow. It is currently unknown how reduced effort pitching compares with maximum effort with respect to elbow stress and ball velocity. Purpose/Hypothesis: The purpose was to determine the correlation between elbow stress and ball velocity with reduced effort pitching. We hypothesized that decreased perceived effort would disproportionately correlate with elbow stress and ball velocity. Study Design: Descriptive laboratory study. Methods: Ten healthy male high school baseball pitchers threw 5 pitches from a regulation pitching mound at 3 effort levels: maximum effort, 75% effort, and 50% effort. Elbow stress, specifically elbow varus torque, was calculated for all pitches using a validated marker-based 3-dimensional motion capture system. Ball velocity was measured using a Doppler radar gun. Intrathrower variability was calculated for each effort level. Results: Elbow stress and ball velocity decreased with reduced effort throws (P < .001 and P = .003, respectively). However, the reductions in elbow stress and ball velocity were not proportional. At 75% effort throws, elbow stress measured 81% (intraclass correlation coefficient [ICC], 0.95), and ball velocity measured 90% (ICC, 0.80) of maximum, respectively. At 50% effort throws, elbow stress measured 75% (ICC, 0.93), and ball velocity measured 85% (ICC, 0.87) of maximum. Intrathrower reliability was excellent for elbow stress and ball velocity, with all ICCs ≥0.80. Conclusion: Pitching at a reduced effort level resulted in decreased elbow stress and ball velocity. However, for every 25% reduction in perceived effort, elbow stress decreased by a mean 13%, and ball velocity decreased 7.5%. When baseball pitchers attempt to throw at a reduced effort of maximum, throwing metrics do not decrease proportionately. Clinical Relevance: While pitching at a reduced effort of maximum decreases elbow stress and ball velocity, the decrease is not proportional, subjecting the elbow to more stress than intended. This has significant clinical importance to pitchers, coaches, and medical professionals in the setting of injury prevention and return to sports.

Elbow stress in youth softball windmill pitchers: predictors of increased torque

Purpose: To assess torque at the elbow in the underhand throwing motion utilizing wearable sensor technology and discover the predictors of medial elbow toque in young female softball pitchers. Methods: Female softball players 12 to 18 years old whose primary position was pitcher and actively participating in sport were studied. Players experiencing throwing arm pain, lower extremity injury hindering pitching motion, or prior surgery were excluded. Age, handedness, height, weight, and throwing arm dimensions were measured and recorded. Pitchers threw 15 pitches, max effort from 43 feet and were given 30 to 60 second rest between pitches. A wearable sensor was placed inside an athletic compression sleeve which recorded data. Measurements included medial elbow torque (Newton-meters; NM), arm speed (peak rotational velocity of the forearm; in rotations per minute; RPM), arm slot (forearm angle in relation to the ground at release; in degrees), and shoulder rotation (maximum forearm angle during the 12 o’clock phase; in degrees). Peak ball velocity in miles per hour (MPH) was measured by a radar gun. Results: Twenty females mean age 15.2 years (range, 12.6-16.9 years) achieved an average elbow stress of 35.5 NM (14-78 NM). Average arm speed measured 583.8 RPM (3502.8 deg/sec) and ball speed ranged from 33-56 mph with an average of 44.1 mph. Multivariate analysis demonstrated arm stress significantly associated with increasing age (P-value 0.00003), and arm length (P-value 0.000006); however, increased forearm length measured a decreased arm stress (P-value 0.00007). Conclusions: There was significant stress measured across the medial elbow in young softball pitchers. Elbow torque was associated with increasing age and total arm length; however, increased forearm length was associated with decreased elbow torque.

Managing the powder coat waste stream: an industrial experimentation approach

Despite acceptance as a functionally and economically competitive alternative to conventional liquid coating, waste generated during powder coating or powder coat waste (PCW) is a notable yet under-examined industrial waste stream. Globally, a large volume of PCW generated during surface finishing processes is landfilled as a fine powder containing microplastics, thereby impacting the environment adversely. In this paper, a step-by-step industrial experimentation methodology based on the principles of the Shainin Design of Experiment was proposed for exploratory experimentation. The proposed methodology offers a convergent approach for diagnostically reducing the process parameters to a controllable number by following a progressive search. A cluster of sanitary ware manufacturing units involved in the surface finishing process was selected as a case study for evaluating the proposed methodology. The results show conveyor hanger pitch, conveyor speed and spray gun pressure as the critical process parameter for dry film thickness (DFT) defect and resulting PCW.

Biomechanical Factors Influencing Post-strike Ball Velocity in Football Players: A Cross-sectional Study

Introduction: Optimising post-strike ball velocity is essential for success in football. Biomechanical factors play a significant role in determining ball speed. However, further investigation is needed to understand the specific relationships between the biomechanical factors and post-strike ball velocity in football players. Aim: To identify the key biomechanical factors contributing to post-strike ball velocity and provide insights for enhancing performance in league-level football players. Materials and Methods: A cross-sectional study was conducted in the Department of Arthroscopy and Sports Medicine at the Sri Ramachandra Centre for Sports Science, Tamil Nadu, India. The duration of the study was five months, from January 2022 to May 2022. The study included 25 professional male football players from national-level league teams. Participants performed maximal instep kicks while various kinematic variables were measured using Vicon cameras, Advanced Mechanical Technology Inc., (AMTI) force footplates, and a radar speed gun. Data processing was performed using Vicon Nexus software version 2.7. The data were analysed using R statistical software version 4.0.2. The Analysis of Variance (ANOVA), followed by Tukey’s Honestly Significant Difference (HSD) post-hoc tests, were used to compare the various kick matrices across the players. Pearson’s r correlation analysis was used to check for a correlation between post-strike ball velocity and other kick matrices. Multiple regression analysis was conducted to examine the relative effects of various kick matrices on post-strike ball velocity, with significance set at a p-value &lt;0.05. Results: The mean age of the study participants was 18.8 years. A significant positive correlation was observed between prestrike foot velocity (r=0.58) and training experience (r=0.48) with post-strike ball velocity. Step-wise multiple linear regression analysis revealed that 39% of the variance in post-strike ball velocity could be attributed to training experience and prestrike foot velocity. Conclusion: Training experience and prestrike foot velocity could be the most important factors to consider in order to maximise post-strike ball velocity among league-level football players.

Speed data collection methods: a review

Various studies have been focusing on a wide range of techniques to detect traffic flow characteristics, like speed and travel times. Therefore, a key aspect to obtain statistically significant set of data is to observe and record driver behaviours in real world.To collect traffic data, traditional methods of traffic measurement – such as detection stations, radar guns or video cameras – have been used over the years. Other innovative methods refer to probe vehicles equipped with GPS devices and/or cameras, which allow continuous surveys along the entire road route.While point-based devices provide information of the entire flow, just in the section in which they are installed and only in the time domain, probe vehicles data are referred both to temporal and space domains but ignore traffic conditions. Obviously, it is necessary that the data collected refer to representative samples, by number and composition, of the user population.The paper proposes a review of the most used methods for speed data collection, highlighting the advantages and disadvantages of each experimental approach. Accordingly, the comparison illustrates the best relief method to be adopted depending on the research and investigation that will be performed.

Effect of Quantitative Partial Valgus Stress During Baseball Pitching on Ball Velocity and Subjective Pitch-Effort.

Excessive elbow valgus stress can often cause pitching elbow injuries, and rehabilitation is usually required before an athlete can resume playing. However, there is a lack of information on the partial load rehabilitation of pitching elbow injuries caused by valgus extension overload based on elbow valgus stress. The purpose of this study was to clarify how quantitative partial elbow valgus stress while pitching affects ball velocity and subjective pitch-effort. Forty-six male baseball pitchers participated in this study. Each player wore a wearable device on the elbow that collected their pitch parameters. Ball velocity was measured using a radar gun. Each elbow valgus stress was measured while each player was instructed to throw five fastballs at full effort. Then, based on the average stress of the five throws (100% partial valgus stress), the 75% and 50% stresses were calculated (75% and 50% partial valgus stress, respectively). Each pitcher continued to pitch until the number of pitches thrown at the targeted elbow stress reached five. Each player was asked about their subjective pitch-effort after completing each type of partial valgus stress pitch. Outcomes were statistically evaluated using either a one-way repeated measures analysis of variance or two-way analysis of variance. The ball velocity was 72% (95% confidence interval [CI], 69%-75%) and 58% (95% CI, 55%-61%) during the 75% and 50% partial valgus stress, respectively (P < .001). Subjective pitch-effort was 41% (95% CI, 38%-44%) and 19% (95% CI, 16%-22%) while pitching at 75% and 50% partial valgus stress, respectively (P < .001). It may be desirable to instruct pitchers to throw at less than 20% subjective pitch-effort of the max if they want to pitch at 50% partial valgus stress. Elbow valgus stress might correlate with ball velocity at 75% partial valgus stress pitch. These results could enable clinicians and coaches to perform safer return-to-throwing programs and prevent excessive load on the elbow.

The Effect of Sex, Maturity, and Training Status on Maximal Sprint Performance Kinetics.

The development of sprint running during youth has received renewed interest, but questions remain regarding the development of speed in youth, especially the influences of sex, training, and maturity status. One hundred and forty-seven team sport trained (69 girls; 14.3 [2.1]y) and 113 untrained (64 girls; 13.8 [2.7]y) youth completed two 30-m sprints separated by 2-minute active rest. Velocity was measured using a radar gun at >46Hz, with power and force variables derived from a force-velocity-power profile. Boys produced a significantly higher absolute peak power (741 [272] vs 645 [229]W; P < .01) and force (431 [124] vs 398 [125]N; P < .01) than girls, irrespective of maturity and training status. However, there was a greater sex difference in relative mean power and peak velocity in circa peak height velocity adolescents (46.9% and 19.8%, respectively) compared with prepeak height velocity (5.4% and 3.2%) or postpeak height velocity youth (11.6% and 5.6%). Sprint development in youth is sexually dimorphic which needs considering when devising long-term training plans. Further research is needed to explore the independent, and combined, effects of sex, training, and maturity status on sprint performance kinetics in youth.

Elbow stress in youth softball windmill pitchers: predictors of increased torque

Purpose: To assess torque at the elbow in the underhand throwing motion utilizing wearable sensor technology and discover the predictors of medial elbow toque in young female softball pitchers. Methods: Female softball players 12 to 18 years old whose primary position was pitcher and actively participating in sport were studied. Players experiencing throwing arm pain, lower extremity injury hindering pitching motion, or prior surgery were excluded. Age, handedness, height, weight, and throwing arm dimensions were measured and recorded. Pitchers threw 15 pitches, max effort from 43 feet and were given 30 to 60 second rest between pitches. A wearable sensor was placed inside an athletic compression sleeve which recorded data. Measurements included medial elbow torque (Newton-meters; NM), arm speed (peak rotational velocity of the forearm; in rotations per minute; RPM), arm slot (forearm angle in relation to the ground at release; in degrees), and shoulder rotation (maximum forearm angle during the 12 o’clock phase; in degrees). Peak ball velocity in miles per hour (MPH) was measured by a radar gun. Results: Twenty females mean age 15.2 years (range, 12.6-16.9 years) achieved an average elbow stress of 35.5 NM (14-78 NM). Average arm speed measured 583.8 RPM (3502.8 deg/sec) and ball speed ranged from 33-56 mph with an average of 44.1 mph. Multivariate analysis demonstrated arm stress significantly associated with increasing age (P-value 0.00003), arm length (P-value 0.000006); however, increased forearm length measured a decreased arm stress (P-value 0.00007). Conclusions: There was significant stress measured across the medial elbow in young softball pitchers. Elbow torque was associated with increasing age and total arm length; however, increased forearm length was associated with decreased elbow torque.

Comparison of Machine Learning Algorithms for Ball Velocity Prediction in Baseball Pitcher using a Single Inertial Sensor

Ball velocity of pitching is an important factor in baseball players. Commonly, ball velocity measurement requires specific devices such as radar gun. On the other hand, Gomaz et al. developed the accurate ball velocity measurement using two inertial sensors on pelvis and trunk. Recently, smartphone installed inertial sensor is popular device in daily life. Therefore, if ball velocity can be measured by only a single inertial sensor, baseball players can measure own ball velocity by only smartphone in daily life and various situations. Thus, the objective of this study is to propose and evaluate the ball velocity prediction method using the only a single inertial sensor. The proposed method predicts ball velocity using by a single inertial sensor and machine learning technique. Five machine learning algorithms (linear regression, support vector machine, gaussian process, artificial neural network, and M5P) predicted ball velocity by data of single inertial sensor, body height, and body weight. In this study, Gomaz et al.’s public data for ball velocity and inertial data during pitching of baseball players were used for this investigation. Sensor placement was either sternum or pelvis. Accuracy of prediction was evaluated by root mean square error (RMSE) between actual and predicted value via leave-one-out cross-validation. The results showed that greatest algorithm (M5P) could accurately predict ball velocity by only single inertial sensor and body parameters (RMSE &lt; 2.0 mph). These results suggest that ball velocity can be measured by only single inertial sensor such as smartphone.

Concurrent Validity and Inter-Rater Reliability of Hand-Held Measurements of Maximal Sprint Speed

Background: Maximal sprinting speed (MSS) is an essential component of success in many sports. Currently, many systems are used to accurately evaluate athletes’ MSS, including laser or radar guns, single- or dual-beam photocells, high-speed cameras, and high-frequency global positioning systems. However, the cost of these devices may be an obstacle to their implementation into practice. The least expensive but most likely less accurate alternative method of MSS evaluation is the hand-held time measurement of a 30m flying-start sprint. Therefore, the aim of the study was to assess the concurrent validity and inter-rater reliability o the hand-held method of MSS measurement. Materials and Methods: The study involved 3 experienced raters and 18 amateur runners. Runners performed 2-3 trials of the 30m maximal flying-start sprint. In total, 40 observations were collected. Each sprint time was measured simultaneously by raters using a hand-held stopwatch and an electronic timing system. Criterion validity (hand-held vs. electronic timing) was assessed using linear regression analysis. Inter-rater reliability between hand-held timers was evaluated using interclass correlation coefficients (ICCs), standard error of measurement (SEM), and minimal detectable change (MDC). Results: Results showed that single and average hand-held methods are affected by -0.17 to -0.07ms-1 (-2.5 to -1.6%) and -0.12ms- 1 (-1.7%) errors, respectively. Linear regression analysis parameters (free parameter not statistically significant, directional coefficient 0.994-1.057, standard error of estimation 0.073-0.125, R2 0.981-0.994) indicated statistically excellent absolute agreement between a hand-held (single and average) and electronic timing. ICCs of 0.980-0.994, SEM of 0.12ms-1 (1.87%), and MDC of 0.34ms-1 (5.18%) indicated statistically excellent absolute agreement and consistency for single and average measurements between hand-held timers. Conclusion: The proposed manual method of MSS measurement underestimates athletes’ speed performance. Moreover, the hand-held 30m flying-start sprint time measurement is affected by a 2% error, and a minimum 5% time change in an individual athlete demonstrates that the change is not simply attributable to measurement error.

Towards Promotion of Road Safety: Crash Diagnosis for the Odumasi-Oterkpolu Road, Ghana

Crashes in road curves contribute significantly to road traffic fatalities in developing countries. The crash risks increase when there are multiple vertical and horizontal curves on the road section. In this study, we diagnose the crash-contributing factors along the crash-prone and curvy Odumasi-Oterkpolu road in Ghana and propose countermeasures. Spot speed counts were done using radar guns in addition to manual traffic counts, field inspections, and victim self-reports. Secondary police crash data (from 2015 to 2019) were collected from the Building and Road Research Institute of Ghana. Multiple regression and descriptive analyses were computed to identify crash-contributing factors. Vehicle brake failure and driver inattention were identified as the main driving errors that contribute to crashes in the road curves. Notably, the majority of crashes involved movements in left-turning lanes, in other words towards drivers’ left sides. Speed, traffic volume, and the volume of motorcycles and medium trucks had the strongest association with fatalities. Overall, the road lacks street lights, guardrails, road signs, road markings, posted speed limits, and durable pavement. This is the first empirical investigation of the studied road; therefore, the findings and proposed countermeasures will help to improve road design and safety measures.