Ball Velocity Research Articles

The Effect of Wearing Soccer Headgear on the Head Response in Soccer Heading

Soccer is regarded as the most popular sport in the world, with millions of people actively involved in the game. Being a contact sport in nature, soccer players are susceptible to various kinds of injuries, such as lower extremities muscle injury. In addition to those familiar injuries that soccer players sustain during the game, traumatic brain injury is also a possibility. Head impacts in soccer could be a result of head-to-head impact with an opponent player, a head-to-elbow impact, an impact with the goal post, an impact with the ground, as well as an impact with the soccer ball, which occurs during a heading manoeuvre. Soccer allows the players to use their heads to hit the ball to pass it to a teammate or even perform heading to score a goal. Although soccer heading is perceived as less harmful as compared to head impacts with other hard objects, many studies have shown compelling evidence that this repetitive heading might harm the brain, thereby leading to traumatic brain injury. Protective headgears designed especially for soccer players have been commercially available in the market for some years. However, the effectiveness of these headgears in reducing the impact due to soccer heading has not been well studied. This paper investigates the effectiveness of two commercially available headgears, the Full90 and the ForceField headgear by means of a heading experiment. An anthropometric test device known as Hybrid III head and neck dummy instrumented with an inertial sensor that consists of a triaxial accelerometer and gyroscope installed at the centre of gravity of the head was used in the experiment. A soccer ball launching machine was used to propel the ball at several inbound velocities. Peak linear acceleration (PLA) and peak angular acceleration (PRA) were recorded, and the head injury criterion (HIC) and the rotational injury criterion (RIC) were calculated. It was found that both headgears failed to reduce the linear components of head acceleration but instead increased the HIC (13 – 66% increment) depending on the inbound ball velocity. With respect to the rotational component of head injury, the Full90 headgear was found to reduce the RIC up to 29%, but the ForceField failed to provide a significant reduction of RIC. Overall, both headgears were found to be ineffective in reducing linear and rotational components of head injury, which could be attributed to the headgear design. Improved headgear design and an improved padded foam are needed to protect soccer player’s brain while performing soccer heading.

Comparison of scapular position in elite tennis players with and without shoulder impingement: A case-control study.

To maximize the ball velocity in the tennis sever, the shoulder plays a key role in the kinetic chain. But shoulder inefficiency leads to shoulder injuries such as shoulder impingement syndrome (SIS). Thus, to verify the scapular movements during the tennis serve could help prevent shoulder injury in tennis players. This case-control study aimed to verify the scapular movements during flat first serve for elite tennis players with shoulder impingement syndrome compared to those without it. Eight elite tennis players (4 males and 4 females) with SIS and 8 elite healthy players (4 males and 4 females) performed flat first serves, and the three-dimensional scapular kinematic data was recorded using the Qualisys motion capture system through spherical reflective markers including the acromion marker cluster. The scapula was more internally rotated (median difference: 10.40∘) in the male players with SIS than in those without it at the maximally externally rotated humerothoracic joint during flat first serve, and female players with SIS (median difference: 7.16∘ and 11.28∘, respectively) had more internally rotated scapula at the maximally externally rotated humerothoracic joint and ball impact. Increased scapular internal rotation may be something that affects shoulder injuries in the overhead sports, and it may help to prevent and rehabilitate overhead injuries including SIS.

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.

Design and Fabrication of Thrower Mechanism for Multipurpose Ball Throwing Machine

The cricket and tennis are one of the popular games in the world. Nowadays the players are trained with the help of practice machine. To simulate different varieties of motions, speeds, and trajectories accurately and repeatedly, practice machine is designed by iterative design processes (manual calculations) with solid works. Two counter rotating wheel mechanism imparts both translational and rotational motions with spin. It is portable, flexible, run-on AC source, operated at various horizontal and vertical planes and desired combinations of both planes. This ball machine was constructed utilizing readily accessible components from the market. Because lowering manufacturing costs is one of the project’s goals, the materials were chosen based on their reduced cost. Furthermore, the machine’s parts are made of recycled and locally sourced materials. Therefore, after building is complete, this machine will be useful to many individuals, especially active gamers. The mathematical analysis for the design of a new tennis ball launcher in order to assess the possibilities for its technical implementation. First, traditional launchers are described. The motion equation of the flying tennis and cricket ball is formulated and numerically solved. This makes it possible to analyze the trajectories of the ball for different initial conditions: elevation angles, velocity of ball. Then, the mathematical analysis of the launcher with two counter rotating rollers is presented.

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 < 2.0 mph). These results suggest that ball velocity can be measured by only single inertial sensor such as smartphone.

The effects of fatigability on shooting skill performance in goalball penalty shots

This study evaluated the influence of acute fatigue on shooting skill performance in goalball penalty shots. Eleven sub-elite male players were evaluated in an official court using a two-dimensional procedure (60 Hz) to compute the mean radial error, bivariate variable error and accuracy, and three-dimensional kinematics (240 Hz) to measure ball velocity. Rating of perceived exertion, blood lactate concentration and knee extension isometric maximal voluntary contractions were assessed at rest and immediately after the completion of an incremental test specific to goalball. Although significant differences were observed for rating of perceived exertion (pre: M = .36 AU, SD = .67; post: M = 9.27 AU, SD = .79), blood lactate concentration (M = 1.33 mM, SD = .51; M = 9.04 mM, SD = 2.25) and peak force (M = 597.85 N, SD = 132.35; M = 513.37 N, SD =107.00) at the end of the incremental test, no differences were identified in the pre and post moments for mean radial error (M = .10 m, SD = 1.01; M =.37 m, SD = 2.19), bivariate variable error (M = 3.56 m, SD = .70; M = 3.25 m, SD = .70), accuracy (M = 3.68 m, SD = .74; M = 3.78 m, SD = 1.13) and ball velocity (M = 18.53 m.s-1, SD = 1.53; M =18.46 m.s-1, SD = 1.65). We concluded that even though significant levels of fatigability can be attributed to the incremental test specific to goalball, shooting skill performance in goalball penalty shots does not appear to be affected. However, further investigations are needed so that goalball coaches can develop strategies that contribute to improve performance in this technical action. Such improvements are decisive for the outcome of a match.

Kinetic and kinematic comparisons in high school pitchers with low and high pitch location consistency.

Although ball velocity has often been associated with increased kinetics at the upper extremity and risk of injury in youth and adolescent pitchers, it is unclear if the performance metric pitch location consistency has any positive or negative associations with pitching kinetics. High school pitchers (n=59) pitched 8-12 fastballs using 3D motion capture (480 Hz). Pitchers were divided into high-consistency (HiCon) and low-consistency (LoCon) groups based on the absolute center deviation of each pitcher's pitch to the center of the pitcher's mean pitch location. Ninety-five percent confidence ellipses with major and minor radii were constructed, and kinematics and kinetics were compared between groups. Compared with LoCon pitchers, HiCon pitchers had decreased lead hip flexion at elbow extension (40°±12° vs. 52°±13°, respectively, P=.008), and at foot contact, decreased back hip extension (-1° ±10° vs. -10° ±13°, respectively, P=.038) and increased back hip internal rotation (9°±15° vs. -2° ± 15°, respectively, P=.043). LoCon pitchers achieved maximum lead hip flexion earlier in the pitch (61.3%±23.2% vs. 75.8%±15.1%, respectively, P=.039). A multiregression model predicted 0.49 of variance in pitch location consistency using kinematic inputs. Pitchers who differ in pitch location consistency outcomes do not appear to demonstrate physiologically unsafe kinematics. High school pitchers who strive for improved pitch consistency can consider adjusting parameters of hip kinematics during early portions of the pitch.

Repetitive bout of controlled soccer heading does not alter heart rate variability metrics: A preliminary investigation.

There is elevated unease regarding how repetitive head impacts, such as those associated with soccer heading, contribute to alterations in brain function. This study examined the extent heart rate variability (HRV) and cardiac baroreceptor sensitivity (BRS) metrics are altered immediately following an acute bout of soccer heading. Seven male elite soccer players (24.1 ± 1.5 years) completed 40 successful soccer headers in 20-min. The headers were performed under controlled circumstances using a soccer ball launcher located 25 meters away and using an initial ball velocity of 77.5 ± 3.7 km/h (heading condition). An accelerometer (xPatch) on the right mastoid process quantified linear/rotational head accelerations. Participants also completed sham (body contact) and control (non-contact) sessions. A three-lead ECG and finger photoplethysmography characterized short-term spontaneous HRV/cardiac BRS, before and after each condition. The SCAT3 indexed symptom scores pre-post exposures to all three conditions. During the heading condition, cumulative linear and rotational accelerations experienced were 1,574 ± 97.9 g and 313,761 ± 23,966 rad/s2, respectively. Heart rate trended toward an increase from pre- to post-heading (p = 0.063), however HRV metrics in the time-domain (ps > 0.260) and frequency-domain (ps > 0.327) as well as cardiac BRS (ps > 0.144) were not significantly changed following all three conditions. Following the heading condition, SCAT3 symptom severity increased (p = 0.030) with a trend for symptom score augmentation (p = 0.078) compared to control and sham. Whereas, symptoms as measured by the SCAT3 were induced following an acute bout of controlled soccer heading, these preliminary findings indicate they were not accompanied by alterations to autonomic function. Ultimately, this demonstrates further research is needed to understand the physiological underpinnings of alterations in brain function occurring immediately after a bout of soccer heading and how these may, over time, contribute to long-term neurological impairments.

Determining Dynamic Mechanical Properties for Elastic Concrete Material Based on the Inversion of Spherical Wave.

The paper presents a new method to study the dynamic mechanical properties of concrete under low pressure and a high strain rate via the inversion of spherical wave propagation. The dynamic parameters of rate-dependent constitutive relation of elastic concrete are determined by measured velocity histories of spherical waves. Firstly, the particle velocity time history profiles in the low stress elastic region at the radii of 100.6 mm, 120.6 mm, 140.6 mm, 160 mm, and 180.6 mm are measured in the semi-infinite space of concrete by using the mini-explosive ball and electromagnetic velocity measurement technology. Then, based on the universal spherical wave conservation equation and the fact that the accommodation relationship in state equation satisfies linear elastic law, the inverse problem analysis of spherical waves in concrete (called "NV + T0/SW") is proposed, which can obtain the dynamic numerical constitutive behavior of concrete in three-dimensional stress by measuring the velocity histories. The numerical constitutive relation is expressed in the form of distortion, and it is found that the distortion law has an obvious rate effect. Finally, the rate-dependent dynamic parameters in concrete are determined by the standard linear solid model. The results show that the strain rate effect of concrete cannot be ignored with the strain rate range of 102 1/s. This study can provide a feasible method to determine the dynamic parameters of rate-dependent constitutive relation of concretes. This method has good applicability, especially in the study of the dynamic behavior of multicomponent composite materials with large-size particle filler.

Using Sensors for Player Development: Assessing Biomechanical Factors Related to Pitch Command and Velocity.

Pitching biomechanical research is highly focused on injury prevention with little attention to how biomechanical data can facilitate skill development. The overall purpose of this study was to explore how sensor-derived segment kinematics and timing relate to command and ball velocity during baseball pitching. We used a cross-sectional design to analyze a series of pitches thrown from 10 collegiate baseball pitchers. We collected biomechanical data from six inertial sensors, subjective command from the pitchers, and ball velocity from a radar device. Stepwise regression analyses were used to explore biomechanical variables associated with command for all pitches and ball velocity for fastballs only. We found that only peak forearm linear acceleration was significantly associated with command, whereas several segment kinematic measures were significantly associated with ball velocity. Our results suggest that different biomechanical variables are linked to specific pithing skills. Our findings suggest that end-effector (forearm) movement is more important for pitch command, whereas proximal-to-distal (pelvis, trunk, upper arm, forearm) segmental movement is important for ball velocity.

Influence of Pelvic Rotation on Lower Extremity Kinematics, Elbow Varus Torque, and Ball Velocity in Professional Baseball Pitchers.

Early pelvic rotation has been associated with decreased throwing arm kinetics in college baseball pitchers, though professional pitchers have yet to be examined. To investigate the effect of pelvic rotation on trunk, pelvis and lower extremity kinematics, as well as throwing arm kinetics and pitch velocity in professional baseball pitchers. Descriptive laboratory study. Data were analyzed for 157 professional baseball pitchers throwing fastballs using 3-dimensional motion capture (480 Hz). Pitchers were divided into an open pelvis (rotated toward target; n = 78) and a closed pelvis (n = 79) group based on pelvic rotation at foot contact. Variables of interest were compared between the groups using t tests and 2-way analysis of variance, while Spearman correlation was used to measure relationships between the variables of interest. Pitchers in the open group had a longer stride length (81% ± 5% vs 77% ± 5% body height; P < .01, d = 0.74), greater lead knee flexion (49° ± 6° vs 47° ± 10°; P = .043, d = 0.33), faster peak knee extension velocity (424°/s ± 158°/s vs 325°/s ± 142 °/s; P < .01, d = 0.66), and faster ball velocity (39.1 ± 1.7 m/s vs 38.4 ± 2.1 m/s; P = .029, d = 0.35) compared with those in the closed group. There was no significant difference in elbow varus torque between the 2 groups (open: 87.8 ± 14.7 N·m, closed: 90.5 ± 17.2 N·m; P = .311). There were moderate negative relationships between pelvic rotation at foot contact and stride length (r S = -0.385, P < .001), lead knee extension (r S = -0.429, P < .001), and peak lead knee extension velocity (r S = -0.359, P < .001). Professional pitchers who landed with an open pelvis demonstrated longer stride length, greater lead knee extension, faster lead knee velocity, and faster ball velocity compared with pitchers with a closed pelvis at foot contact. This increase in segment velocities and ball velocity was not associated with an increase in elbow varus torque and displays a potentially efficient method in which pitchers can increase ball velocity without an increase in elbow varus torque. Instructing pitchers to rotate their pelvis toward the target at foot contact may allow pitchers to transfer momentum up the kinetic chain more efficiently, while producing greater ball velocity and limiting the torque sustained at the elbow.

The Effects of a Weighted Football Intervention on Ball Velocity of a Standard Football Place-Kick among Elite Gaelic Football Goalkeepers: A Single-Subject Designed Study.

Weighted football place-kicking acutely enhances the ball velocity (BV) of subsequent standard football place-kicks. However, there is a dearth of research examining the long-term effects of such interventions, with less evidence in existence among elite athlete cohorts. Therefore, the purpose of this study was to investigate the individual effects of a 4 week, eight-session weighted Gaelic football intervention on BV of standard Gaelic football place-kicks among six elite male Gaelic football goalkeepers. This research design was based on a pre-, mid-, post-, and retention-test design. A linear mixed model analysis was employed, with time and participants as fixed effects, and the number of place-kicks per testing session as a random effect. Post hoc tests revealed significant changes in BV for five of the six participants (p < 0.05), with three participants experiencing significant BV increases from pre-test to post-test (p < 0.05), while no significant differences were found between post-test and retention-test. The remaining three participants experienced no significant BV differences from pre-test to post-test and retention-test. These findings suggest that a weighted football place-kicking intervention can be a time-efficient means of maintaining and enhancing BV and, thus, kick distance, among elite goalkeepers during pre-season and in-season phases.

Discrete Dynamics of Balls in Cageless Ball Bearings

Cageless ball bearings are often preferred as a back-up bearing for active magnetic bearings to support a falling rotor, but the contact between the balls of the cageless ball bearing may lead to the deterioration of the bearing performance and affect the dynamic stability of the rotor system. Thus, we studied the discrete dynamics of cageless ball bearings. First, a model is proposed to change the groove curvature center of the local outer raceway to control the ball velocity to achieve dispersion. Combined with the spatial geometry theory, the mathematical model of the discrete raceway is established, the collision between the balls is considered as an abruptly added constraint, and the non-smooth dynamics equation of the cageless ball bearing with a local discrete raceway is established. Then, the fourth-order Adams prediction correction algorithm is used to numerically solve the dynamic discretization of the ball, and the structural parameters of the discrete raceway are preferably selected, according to the phase diagram of the ball and the change in the angular spacing. The results show that the structure of the discrete raceway has a strong influence on the discrete dynamics of the ball.

Sex difference in soccer instep kicking

ABSTRACT We aimed to clarify the differences in soccer instep kicking dynamics between sex groups. The instep kicking of seven female (height: 160.3 ± 6.1 cm; mass: 54.3 ± 5.2 kg) and seven male (height: 173.0 ± 5.9 cm; mass: 70.0 ± 9.0 kg) players were recorded by a motion capture system (500 Hz). Joint moments of the kicking leg were computed and normalized by the body mass and height. Statistical parametric mapping was used to compare the entire kicking motion between the two groups. Significantly slower resultant ball velocity seen in female players was most likely explained by their significantly slower run-up velocity, shorter leg length and lower foot–ball velocity ratio. Female players exhibited significantly smaller knee joint moment in the latter part (80–86%) of kicking. Also, significantly smaller positive work done by knee extension moment and the ratio of work (knee extension/hip flexion) were found in female players. These results suggested that the suppressed knee extension moment action was identified as a key kinetic characteristic in the instep kicking of female players, and to compensate for this action, they more rely on the work due to hip flexion moment to execute the instep kicking.

Numerical Simulation of Bridging Ball Plugging Mechanism in Fractured-Vuggy Carbonate Reservoirs

Pores, fractures, caves, and other storage spaces are commonly distributed in fractured-vuggy carbonate reservoirs. During the drilling process, more than half of all drill-in fluid loss issues are caused by developed caves. Cave scales range from centimeters to meters, making leak prevention increasingly difficult through the use of traditional technologies. Currently, there is still high demand for the understanding of feasible loss control techniques, especially in fractured-vuggy carbonate reservoirs. Multistage Bridge Plugging (MBP) technology has facilitated pioneering experiments in many oilfields, but the success rate of plugging is less than 50%, and the effects of plugging are uncontrollable and difficult to predict. This is due to a lack of clarity regarding the plugging mechanism and the key controlling factors. In this study, we used the Discrete Element Method (DEM) simulation method to investigate the controlling factors of MBP technology, and analyzed its applicable conditions. We found that the prerequisite for the success of MBP is the presence of a constricted throat near the wellbore when drilling the well hole; the first-stage bridging ball is the key to the success of MBP. Larger ball radius, cave inclination and initial flow rate, and lower ball velocity are beneficial to the first-stage bridging. All discussion in this research is based on the ideal situation. However, the cave pattern is difficult to describe using several models, let alone by one ideal model. With the progress of seismic fine description technology and mud logging, more accurate characterization of caves in carbonate reservoirs will help to accurately formulate the plugging scheme and greatly improve the success rate of plugging technology. Additionally, the engineering risks of this technology, such as plugging the coiled tubing, need to be further studied.

Determinants of Biomechanical Efficiency in Collegiate and Professional Baseball Pitchers

Background: Biomechanical efficiency, defined as fastball velocity per unit of normalized elbow varus torque, is a relatively new metric applied to improving the performance and health of baseball pitching. Purpose/Hypothesis: The purpose of this work was to evaluate kinematic parameters influencing biomechanical efficiency among professional and collegiate pitchers. Kinematic differences were compared between pitchers of high and low biomechanical efficiency. We hypothesized that professional pitchers would have greater biomechanical efficiency than collegiate pitchers. Study Design: Descriptive laboratory study. Methods: A deidentified biomechanical database of 545 pitchers (447 professional, 98 collegiate) was analyzed. A multivariate linear regression model was used to evaluate significant findings a priori with α = .05. Additionally, biomechanical differences were identified between competition levels and between high and low biomechanical efficiency groups using Mann-Whitney U test (α = .05). Results: Competition level and 11 (of 21) kinematic variables explained 27% of the variance in biomechanical efficiency, with most of the predictors being throwing arm kinematics (elbow flexion at stride foot contact [SFC]: β, −1.47; SE, 0.26; shoulder abduction at SFC: β, −1.78; SE, 0.39; shoulder external rotation at SFC: β, 0.60; SE, 0.22; maximum external rotation [MER] angle: β, 1.82; SE, 0.42; shoulder horizontal adduction at MER: β, −3.42; SE, 0.71) (all P≤ .05). Professional pitchers had greater biomechanical efficiency than collegiate pitchers (711.0 ± 101.0 vs 657.0 ± 99.3, respectively; P < .001; d = 0.53). Compared with the low-efficiency group, the high-efficiency group had significantly lower normalized elbow varus torque with greater weight and height (high: 0.047 ± 0.004 %wt*ht vs. low: 0.063 ± 0.006 %wt*ht, P <.001; d = 3.20). At the instant of SFC, the high-efficiency group demonstrated greater shoulder external rotation and less elbow flexion, shoulder abduction, and pelvic rotation. The high-efficiency group also had greater MER and less shoulder horizontal adduction at MER, trunk side tilt at ball release, and knee excursion from foot contact to ball release. Conclusion: Professional pitchers had greater biomechanical efficiency than collegiate pitchers. Biomechanical efficiency was also affected by 11 kinematic variables identified in this study. Pitchers with higher efficiency had distinct differences in arm position, trunk side tilt, and lead-knee extension range of motion in the delivery. Thus, pitchers and baseball organizations should focus on these factors to lower normalized elbow varus torque relative to ball velocity.

Physical Performance Indicators and Team Success in the German Soccer League

The aims of this study were (1) to determine the match running performance required by different teams based on their final ranking position and (2) to analyze the association between match running performance variables and team success at the end of the season. A total of 1,224 match observations from professional soccer teams competing during two consecutive seasons in the German Bundesliga were analyzed. In addition, the final league ranking position and the total of points obtained by each team at the end of the season were registered for the analysis of the association between team success and match running performance. The main findings were that high ranked teams covered the greatest total distance with ball possession, sprinting distance with ball possession, and completed the greatest number of sprinting actions with ball possession and maximal velocity. Moreover, total distance covered with possession of the ball and maximal velocity were the most important variables to predict the total of points obtained at the end of the season. Specifically, the relative contribution of total distance covered with ball possession to the total of points obtained was greater than maximal velocity. Training programs for professional soccer players should be focused on improving the sprint capacity and running with possession of the ball (e.g., transitional tasks and small-sided games). Moreover, this has implications for injury prevention, physical, psychological, and technical-tactical training since today’s soccer requires players to engage in repeated high-intensity actions, reach maximum speeds above 9 m/s, and develop technical-tactical coordination when running with the ball.

Hip and knee joint angle patterns and kicking velocity in female and male professional soccer players: A principal component analysis of waveforms approach

ABSTRACT This study used principal component analysis (PCA) of waveforms to extract movement patterns from hip and knee angle time-series data; and determined if the extracted movement patterns were predictors of ball velocity during a soccer kick. Twenty-three female and nineteen male professional soccer players performed maximal effort instep kicks while motion capture and post-impact ball velocities data were recorded. Three-dimensional hip and knee joint angle time-series data were calculated from the beginning of the kicking leg’s backswing phase until the end of the follow-through phase and entered into separate PCAs for females and males. Three principal components (PC) (i.e., movement patterns) were extracted and PC scores were calculated. Pearson correlation coefficients were calculated to establish correlations between hip and knee PC scores and kicking velocity. Results showed better kicking performance in male players was associated with a greater difference between the hip extension at the end of the backswing/beginning of the leg cocking phases and hip flexion at the end of the follow-through phase (r = −0.519, p = 0.023) and a delayed internal rotation of the hip (r = 0.475, p = 0.040). No significant correlations between ball velocity and hip and knee kinematics were found for female players.

The influence of excessive ipsilateral trunk tilt on upper-extremity throwing mechanics: a newly characterized parameter for biomechanical evaluation in high school and professional pitchers.

Although contralateral trunk tilt has been recognized, the phenomenon of excessive ipsilateral trunk tilt, often observed during earlier portions of the pitch, has not been explored as a potential correlate with throwing-arm kinetics among baseball pitchers. The purpose of this study was to evaluate kinetic and kinematic parameters among high school and professional pitchers related to excessive ipsilateral and contralateral trunk tilt. Professional and high school pitchers were assessed with a 3-dimensional motion capture system (480 Hz) while pitching. Pitchers were grouped as follows: excessive ipsilateral tilt at foot contact (FC), neutral, or excessive contralateral tilt at ball release (BR). Trunk and shoulder kinematics as well as throwing-arm kinetics were compared between subgroups via post hoc regression analysis. Professional pitchers (n=287) had significantly higher ipsilateral trunk tilt at FC (P<.001) than high school pitchers (n=59). High school pitchers with excessive contralateral trunk tilt at BR experienced significantly higher shoulder superior force (27.0%±7.4% body weight [BW] vs. 17.6%±5.1% BW, P<.001) and shoulder anterior force (39.6%±8.2% BW vs. 35.7%±5.4% BW, P<.001) compared with the ipsilateral trunk tilt cohort but had comparable ball velocity (30.2±3.2 m/s vs. 30.4±2.1 m/s, P=.633). For professionals, for every 10° increase in ipsilateral trunk tilt at FC, ball velocity increased by 0.2 m/s (B = 0.02, β = 0.07, standard error [SE] = 0.005, P= .010) whereas elbow varus torque decreased by 0.1% BW × height (B = -0.01, β = -0.08, SE = 0.002, P<.001) and shoulder internal rotation torque decreased by 0.1% BW × height (B = -0.01, β = -0.07, SE = 0.002, P= .005). High school and professional pitchers with excessive ipsilateral trunk tilt at FC consistently demonstrated significantly decreased throwing-arm kinetics (shoulder anterior force and shoulder superior force for high school pitchers and shoulder internal rotation torque and elbow varus torque for professional pitchers) compared with pitchers with excessive contralateral trunk tilt at BR, with equivalent ball velocity. In addition, professional pitchers appeared to engage in significantly greater ipsilateral trunk tilt during early portions of the pitch when compared with high school pitchers, which may represent a kinetically favorable method adopted by pitchers at higher playing levels to maintain adequate ball velocity while concomitantly minimizing throwing-arm kinetics.

Trail Leg Hip Power: Influence On Elbow Varus Torque In Baseball Pitchers

Although excessive elbow varus torque has been reported to contribute to ulnar collateral ligament (UCL) injury in baseball pitchers, contributing factors remain relatively unknown. The lower extremities generate power that is transferred up through the kinetic chain in pitching. Specifically, the trailing hip generates triplanar power during the stride phase. Diminished trailing hip power generation during pitching may necessitate compensatory power generation at the trunk and shoulder, potentially impacting elbow torque. PURPOSE: To determine the relationship between hip power and elbow varus torque during pitching. METHODS: Participants (n = 48) were high-school and collegiate baseball pitchers (17.6 ± 2.5 yrs, 1.85 ± 0.06 m, 84.7 ± 13.4 kg). Reflective markers were placed on the bilateral lower extremities (femoral condyles, malleoli, calcaneus, and distal foot), spine, scapulae and both upper extremities (acromia, humeral epicondyles, styloids of the wrist, and hand). Kinematics and kinetics (instrumented mound) were obtained from the trail limb during 3 maximal effort fastball pitches (36.9 ± 2.5 m/s). Ball velocity (m/s) was measured using an automated ball tracking system. Stride phase was defined as the time between peak stride knee height and stride foot contact. Elbow varus torque and hip power were quantified using inverse dynamics equations and normalized to body weight. Hip power was calculated as the resultant sum of X, Y and Z components expressed in the hip joint coordinate system. Linear regression was used to evaluate the relationship between peak elbow varus torque and hip power, using ball velocity as a covariate. Significance was set to 0.05. RESULTS: Peak hip power was found to be negatively associated with peak elbow varus torque (B = -0.02, p = 0.003, R2 = 11.2%). CONCLUSION: Lower hip power production is associated with higher elbow varus torque during the stride phase of pitching. Greater use of the trail hip during the stride phase may allow pitchers to decrease elbow torque while maintaining ball velocity. Future work should explore intermediate relationships in the pitching kinetic chain to establish a mechanism by which increased hip power may mitigate elbow varus torque in pitching.