Ball Velocity Research Articles

Developmental differences of kinematic and muscular activation patterns in instep soccer kick

ABSTRACT Kinematic and neuromuscular activity differences amongst soccer players in different age groups were examined in this study. Thirty male soccer players evenly divided into three age groups (Group 1: age 12–13; Group 2: age 14–15; Group 3: age 16–17) were asked to perform instep kicks towards a target 11 m away. Their anthropometrics, instep kick kinematics, resultant ball velocities, both legs isokinetic strength, and electromyography (EMG) during kicking were compared amongst the three age groups. There were significant differences in height, body mass, body mass index, ball velocities, and isokinetic strength values amongst three age groups. Also, kicking kinematics including angular and linear velocities of hip, knee, ankle, and toe were significantly different (p < 0.05) amongst groups in several kicking phases. Furthermore, the activities of m. rectus femoris, m. vastus medialis, m. biceps femoris were significantly different amongst groups (p < 0.05). The ball velocities and leg strength parameters increased with age, neuromuscular activations, and kinematic parameters differed especially in leg-coking and forward swing phase of instep soccer kick. It should be concluded that an increase of resultant ball velocity of the instep kick is closely associated with chronical age, the development of leg muscle strength, and the neuromuscular activity of the kicking leg.

Influence of stride length on upper extremity joint moments and ball velocity in collegiate baseball pitchers

ABSTRACT The initial stride down the mound is an important aspect of the baseball pitch. Understanding the implications of stride length is essential to appropriately coach baseball pitchers. The purpose of this study was to determine the association between normalised stride length and the elbow varus and glenohumeral internal rotation moments, ball velocity, trunk and pelvic rotation and forward trunk tilt. Motion analysis data collected from 99 collegiate pitchers were analysed for this study. A random intercept, mixed-effects regression model was used to determine if there were statistically significant associations between normalised stride length and the variables of interest. Secondary analyses were conducted to determine if an optimal stride length existed in this cohort. No significant associations were found between normalised stride length, ball velocity, or upper extremity joint moments. Additionally, no optimal stride length was identified; however, trends indicate that stride lengths between 131%–137% of a pitcher’s leg length may be beneficial. Normalised stride length was associated with both trunk and pelvic rotation at foot contact (p < 0.001). Trunk and pelvic rotation has been previously shown to be associated with ball velocity and joint moments, indicating that stride length may have an indirect effect on ball velocity and joint moments.

Effects of soccer ball inflation pressure and velocity on peak linear and rotational accelerations of ball-to-head impacts

Exposure to head impacts is common in soccer and, in some cases, has been associated with neurocognitive and physiological consequences in soccer players. Ball-to-head impacts are particularly frequent, as soccer players regularly use their heads to pass, clear, and shoot the ball during game play and practice. The attenuation of head accelerations resulting from impact is of interest to promoting athlete brain health and numerical models have suggested that reducing soccer ball inflation pressure can lower head accelerations from ball-to-head impacts. The present study sought to test the effect of ball inflation pressure on peak linear acceleration and peak rotational acceleration of the head in a biomechanical reconstruction of ball-to-head impacts using an anthropomorphic testing device head and neck. Adult-sized soccer balls were inflated to five different pressures (34, 48, 55, 62, and 76 kPa), a range that spanned the lower bound on inflation pressure regulated by Federation Internationale de Football Association and the National Collegiate Athletic Association (60 kPa). Balls were then thrown via a ball launcher at the forehead of the anthropomorphic testing device at three different velocities (17.3, 19.7, and 22.2 m/s). Repeated-measures analyses of variance, with pressure and velocity as repeated measures, revealed an increase in peak linear acceleration (p = 0.001) and peak rotational acceleration (p = 0.002) with higher ball velocities, and a decrease in peak linear acceleration (p < 0.001) and peak rotational acceleration (p < 0.001) with lower ball pressures. Consistent with previous numerical models, the results of this study suggest that reducing soccer ball inflation pressure may reduce head accelerations of ball-to-head impacts.

Effect of football boot upper padding on shooting accuracy and velocity performance

Football boots are marketed with a specific performance feature focus, for example, power boots are marketed for optimal shooting performance. However, little evidence exists on the impact of boot design on shooting performance. This study assessed the effect of upper padding on shooting velocity and accuracy using a test–retest reliable test setup. Nine university level football players performed a protocol of shooting to: (1) maximise velocity; and (2) maximise accuracy in football boots with and without upper padding (Poron Memory foam). The protocol was completed twice; the non-padded boot results were used for test–retest validation, while the non-padded versus padding results were used to investigate the effect of padding. Velocity was assessed through actual ball velocity, percentage of maximum velocity and perceived velocity. Accuracy was assessed through radial offset, vertical offset, horizontal offset, success (goal/no goal), zonal offset and perceived accuracy. No significant differences between boots were observed in the velocity measures for either velocity or accuracy focused shots. Significant differences between boots were observed in vertical offset for both accuracy (without padding mean ± standard deviation − 0.02 ± 1.05 m, with padding 0.28 ± 0.87 m, P = 0.029) and velocity (without padding 0.04 ± 1.33 m, with padding 0.38 ± 0.86 m, P = 0.042) focused shots resulting in more missed shots above the goal for the padded boot (without padding 41–43% missed, with padding 56–72% missed). These findings suggest the addition of upper padding has a negative impact on shooting accuracy while not impacting shooting velocity.

Factors Associated with Ball Velocity and Low Back Pain During Kicking in Adolescent Soccer Players.

PurposeThe factors associated with low back pain (LBP) and the relationship between LBP and ball velocity during kicking motion of adolescent soccer players remain largely unknown. This study aims to clarify the relationship between increasing ball velocity and LBP in adolescent soccer players.Participants and MethodsAdolescent soccer players were divided into two groups according to the presence and absence of LBP (LBP group, n=38 and NBP (no back pain) group, n=29, respectively). Real-time kick motion was measured using a three-dimensional motion analysis system and the angle of the lumbar spine, hip, and center of mass (COM) were calculated. Regression analysis was used to identify factors associated with ball velocity and LBP. In addition, Pearson’s correlation coefficients were determined between the angle of the lumbar spine and hip, and ball velocity and position of COM in the extracted phase from regression analysis.ResultsThe major factor associated with increasing ball velocity was the rotation angle of both hips (Adjusted R2=0.244) and vertical position of COM during kicking (Adjusted R2=0.262). Furthermore, the factors associated with LBP were the flexion angle of kick-side hip (OR=1.126) and abduction angle of both hips (kick-side OR=1.124; support-side OR=0.872). The factors for ball velocity and LBP were related to the maximum hip extension phase. In the hip extension phase of kicking, compared with the NBP group, the LBP group showed lesser extension and external rotation of the kick-side hip angle. In the hip flexion phase of kicking, the ball velocity was correlated with vertical (r=0.56)/anterior (r=0.46) position of COM in the NBP group.ConclusionTo compensate for this restricted hip motion, the LBP group could extend and rotate their lumbar spine, which may likely cause stress to this region.

Biomechanical Analysis of an Overhead Baseball Throwing Movement Associated with a Cardiorespiratory Fatigue Effect

Background: Overhand pitching is a movement that requires the coordination of lower extremity, trunk, and upper extremity segments to effectively transfer force throughout the kinetic chain to project a baseball. Objective: The purpose of this study was to investigate the effect of cardiorespiratory fatigue on throwing ball velocity related to kinematics motion changes in baseball. Methods: The study samples included 12 male baseball athletes (19.3 ± 2.8 years old, height of 1.71.4 ± 3.1 m, and weight of 64.3 ± 3.6 kg). A descriptive quantitative method approach was used. The instruments included two high-resolution handycams (Sony HXR-MC2500, Japan), a high-speed camera (Fastec Imaging TS5-H, USA), a radar speed gun (Bushnell 101922, Germany), a 3D force platform (The AMTI Optima Series 20210, USA), 14 point manual markers, a motion capture system software (Frame DIAZ IV, Japan), and a heart rate sensor (Polar H10, Finland). Results: The results of this study showed that there were significant differences in the ball velocity (p= 0.042), stride length percentage height (p= 0.041), elbow flexion (p= 0.046), maximum shoulder horizontal adduction (p= 0.041), maximum elbow extension angular velocity (p= 0.035), maximum shoulder internal rotation (p= 0.029), and lateral trunk tilt (p= 0.029) when the pitchers were fatigued. Conclusion: Cardiorespiratory fatigue causes changes in the kinetic harmonization of upper and lower body motion, which results in a decrease in the ball velocity. These results are similar to those in previous studies conducted with the intervention of muscle fatigue during overhead baseball throwing, which causes a decrease in the performance and ball velocity.

The Immediate Effect of Spinal Manipulation on Ball Velocity and Neuromuscular Function During an Instep Kick in Former Varsity Soccer Players: A Feasibility Study.

Corso, M, Liang, L, Tran, S, Howitt, S, Srbely, J, and Mior, SA. The immediate effect of spinal manipulation on ball velocity and neuromuscular function during an instep kick in former Varsity soccer players: a feasibility study. J Strength Cond Res 36(9): 2558-2565, 2022-Spinal manipulation (SM) has been shown to increase ball velocity (BV) in soccer players. Evidence suggests that SM modulates responses at spinal or cortical levels to enhance force production in asymptomatic populations. No studies have explored the underlying neuromuscular mechanisms contributing to changes in BV post-SM in soccer players. We assessed the feasibility of measuring change in BV and neuromuscular function after SM in former Varsity level soccer players with a pre-post study design. Three to 5 maximal instep kicks were performed before and after SM at the L3-5 level. Ball velocity was measured using high-speed camera. Activation of lower limb and trunk musculature was recorded with electromyography. Outcomes included ease of recruitment, scheduling and data capture, as well as expectation and perception of SM effect and adverse events (AE). Fifteen potential subjects were recruited over 1.5 months. Eleven were scheduled (24-31 years; 8 females, 3 males). Two subjects reported mild AE after maximal voluntary isometric contraction testing. A significant increase in BV (mean change: 1.75 m·s -1 [95% confidence interval: 0.5-3.0]) and a trend to increased peak-activation of knee extensors (90.7%) were observed post-SM. Findings suggest that our recruitment strategy and methodology are feasible in a larger trial with some modifications. Our preliminary findings support previous research by suggesting that increased BV may be mediated through increased activation of knee extensors during the kick. Our findings may offer additional insight into the underlying neuromuscular mechanisms contributing to immediate change in BV post-SM.

Positive Relationships Between Golf Performance Variables and Upper Body Power Capabilities.

Sorbie GG, Glen J, and Richardson AK Positive relationships between golf performance variables and upper body power capabilities. J Strength Cond Res 35(12S): S97-S102, 2021-The importance of lower body and trunk strength and power, as well as upper body strength in golf is well documented; however, the relationship between upper body power and golf performance has yet to be determined. Therefore, the purpose of the study was to investigate the relationships between golf performance and upper body power. Thirteen golfers (mean ± SD: age: 30 ± 7 years and handicap: 6.1 ± 4.9) participated in the study. Club head velocity (CHV) and ball velocity were measured during the golf test. To assess upper body power, subjects completed a ballistic bench press and upper body Wingate test. Pearson product-moment correlations were used to assess the relationships between golf performance and upper body power. The results demonstrated that there were strong relationships between ballistic bench press and CHV and ball velocity when using the driver (r > 0.6-0.7), and moderate-to-strong relationships (r > 0.4-0.6) when using the 7-iron. Strong relationships were found between the upper body Wingate test and CHV and ball velocity (r > 0.5-0.8) when using the driver and 7-iron. As a result of the findings, strength and conditioning coaches may use both the ballistic bench press test and the Wingate test as a primary assessment to measure the effectiveness of upper body training interventions with the aim of improving golf performance. Although, when performing the golf swings at higher velocities (i.e., with the driver), the ballistic bench press may be more beneficial.

The Effects of Target Location Upon Throwing Velocity and Accuracy in Experienced Female Handball Players.

The purpose of this study was to investigate the effect on throwing performance (velocity and accuracy) of experienced female handball players when throwing at four different targets in a handball goal. Thirteen experienced female handball players (age 18.2 ± 1.7 years, height 1.7 ± 0.10 m, mass 68.1 ± 19.6 kg, and training experience 9.5 ± 3.7 years) performed 10 throws from a 7 m distance at each corner of the handball goal with maximal effort. Maximal ball velocity was recorded with a radar gun together with mean radial error, centroid error, and bivariate variable error, as measurements of accuracy. The main findings were that the ball velocity was higher when throwing at targets at the ipsilateral side, compared with the contralateral side, while throwing consistency (bivariate variable error) decreased when throwing at the contralateral side upper corner. No velocity-accuracy trade-off was found between the four targets. Based upon the findings, it is suggested that players throw to the (upper) ipsilateral side of the goal when performing a penalty throw, dependent on the goalkeepers’ position, since the ball velocity is the highest here, without losing accuracy. This gives the goalkeeper less time to react and stop the ball, thereby giving the player the highest chance of scoring.

Analysis of Kinematic and Anthropometric Variables of the Spike Execution Technique of Volleyball

The research aimed to analyzed the kinematic and anthropometric variables of the spike execution technique of volleyball. 36 junior India level players from all over India of 16 - 20 years, age group were to be selected as subjects for the study. Purposive sampling technique was used for the selection of subjects. Participants were required to deliver five relevant spiked execution attempts as well as the perfect trial used for the analysis. Elite coaches who were available during the evaluation for grading. The moment execution of the spike was measured based on certain criteria (10 point system). A Go Pro Hero 5 (camera) with a frequency of 240 frames per second was placed on the sagittal plane to measure kinematic parameters. Based on sequence photographs the scholar developed stick figures from which selected biomechanical variables were calculated. The stick figures, angle of different joints, the center of gravity were developed by kinovea version 0.8.27 software. Body segments (i.e., standing height, upper arm, lower arm, palm length, upper leg, and lower leg length) were measured by the anthropometric kit. The multiple regression analysis was to be used to find out the prediction of kinematic & anthropometric variables of the spike execution technique of volleyball at 0.05 level of significance. Results of this study shows the value of R2 is 0.883 in selected kinematic variables and 0.119 in selected anthropometric variables. It may be interpreted that all the four kinematic variables selected in the model namely, angle at right wrist, angle at right elbow, angle at right shoulder, and ball velocity and the anthropometric variable selected in the model name, palm length have significant predictability in estimating the value of the moment execution technique of spike in volleyball. The result concluded that the kinematic variables i.e., ball velocity, angle at right wrist, angle at right elbow, angle at right shoulder and palm length in anthropometric measurement are contributed in the moment execution to creat a maximum speed, force and accuracy in the spike technique of volleyball. This study also contributed in the best way to execute the technique of spike for performance enhancement of volleyball players. It is suggested that the results of this study provide useful information for coaches to training in upper body strength & flexibility levels for attempting to increase range of joint movement, hiting with accuracy of the spike technique and its helps in injury prevention of volleyball players.

SrAl2O4:Eu,Dy mechanoluminescent flexible film for impact sensors

The present work is devoted to make a mechanoluminescent film for making an impact sensor that is flexible, durable and non-destructive. For this, a flexible film of SrAl2O4:Eu,Dy phosphor is prepared by mixing SrAl2O4: Eu,Dy with polydimethylsiloxane (PDMS). The XRD patterns indicate the formation of a monoclinic phase of SrAl2O4: Eu,Dy phosphor. The SEM images reveal the surface morphology of the reported samples (powder and film). In order to measure the mechanoluminescence (ML) intensity, the flexible film is excited impulsively with a steel ball. Snapshots of ML patterns taken with cathode ray oscilloscope are presented to visualize the activity exactly. Variations in peak ML intensity and total ML intensity with time are discussed. The photoluminescence (PL) spectra are found to peak at 520 nm when excited with 365 nm wavelength. The broad green emission obtained from flexible film is attributed to 4f65 d1→4f7 transitions. The time corresponding to peak ML intensity (tm) does not change much with increasing impact velocity of the steel ball. The ML behaviour under cyclic loading is also recorded and analyzed. When SrAl2O4:Eu,Dy flexible ML film is rubbed with smooth glass rod, it produces the ML pulses of different intensities. These characteristics are useful for the development of the pressure and impact sensors.

The relationship between shoulder range of motion and elbow stress in college pitchers

College pitchers with increased external rotation gain (ERG) produce increased medial elbow torque (elbow stress)whereas those with reduced total rotational range of motion (ROM) have reduced medial elbow torqueduring pitching. Pitchers were recruited from 3 college baseball teams. Players with prior injury or on pitching restrictions because of pain were excluded. Players were evaluated within 2 weeks before their first game of the season. Pitchers completed an intake survey, and shoulder and arm measurements were taken. Pitchers were fitted with a baseball sleeve that included a sensor at the medial elbow. The sensor calculated elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. After adequate warm-up, pitchers threw 5 fastballs in a standardized manner off the mound at game-speed effort. The primary outcome evaluated the relationship between shoulder ROM and medial elbow torque. Additional outcomes evaluated pitcher characteristics and demographic characteristics in the context of shoulder ROM. Twenty-eight pitchers were included in the preseason analysis. The average age and playing experience were 20.1 years (standard deviation [SD], 1.3 years) and 15.3 years (SD, 1.8 years), respectively, with 2.5 years (SD, 1.2 years) playing at collegiate level. The dominant shoulder showed decreased internal rotation and increased external rotation (ER) relative to the nondominant side (P < .001). The average glenohumeral internal rotation deficitand ERG were 11.3° (SD, 9.87°) and 5.71° (SD, 8.8°), respectively. ERG ≥ 5° was a significant predictor of elbow stress during pitching (47.4 Nm [SD, 0.7 Nm] vs. 45.1 Nm [SD, 0.6 Nm], P = .014). Univariate associations showed that each additional degree of ER resulted in increased elbow torque (β estimate, 0.35± 0.06 Nm; P = .003). Conversely, decreased medial elbow torque was found in pitchers with reduced shoulder ROM (glenohumeral internal rotation deficit ≥ 20°: 43.5 Nm [SD, 1.1 Nm] vs. 46.6 Nm [SD, 0.5 Nm], P = .011; loss of total rotational ROM ≥ 5°: 43.6 Nm [SD, 1.1 Nm] vs. 46.6 Nm [SD, 0.5 Nm], P = .013)and in those with greater arm length (P < .05). College pitchers with increased ER produce greater medial elbow torque during the pitching movement. Each degree of increased ER was found to correlate with increased elbow torque and ball velocity. On the contrary, arm length and reduced shoulder ROM were associated with reduced medial elbow torque. This study suggests that increased ER in pitchers is associated with greater elbow stress during pitching.

The impact of distance and the crow hop on medial elbow stress during an interval throwing program

Objectives:Rehabilitation programs following ulnar collateral ligament reconstruction include an interval throwing program in order to gradually increase stress and prevent excessive elbow valgus loads. These programs often instruct players to use the crow hop, even at short distances, in order to reduce stress on the reconstructed ligament. The purpose of the study was to evaluate the impact of the crow hop on medial elbow stress at various distances of an interval throwing program.Methods:High school and college-aged baseball players were recruited for this study. Players threw at distances of 30, 45, 60, 90, 120, 150, and 180 feet. At each distance, participants made 3 throws while using a crow hop and 3 throws without using a crow hop with the instruction to throw on an arc. A wearable device recorded elbow torque, arm slot, arm speed, and shoulder rotation. Ball velocity was measured using radar gun.Results:A total of 20 players participated in this study. Overall elbow torque at each distance was 12.9, 20.5, 26.3, 31.9, 34.7, 36.1, and 37.1 Nm, respectively. There was no difference in elbow stress for throws with a crow hop compared to throws without a crow hop at any distance of throwing (p > 0.05). There was no difference in elbow torque for throws at 150 feet compared to 120 feet (p = 0.10) or 150 feet compared to 180 feet (p = 0.83); however, there were significant increases in elbow torque between every other throwing distance (p < 0.05).Conclusions:Medial elbow torque significantly increases at greater throwing distances of a standard interval throwing program, although the effect becomes less pronounced at longer distances as players maximize effort. The crow hop does not affect medial elbow torque at any distance of throwing.

Mechanism of migration and settlement for temporary plugging ball in shale gas horizontal wells

In order to determine the migration and settlement mechanism of temporary plugging balls in horizontal wells, the rules for distribution, migration and settlement of balls in different location were researched through calculation, coupling fracturing fluid and characteristics of movement based on CFD (computational fluid dynamics), DEM (discrete element method) and DDPM (dense discrete phase model), and the intensity, plane and spatial distribution of the microseismic events before and after ball-addition were analysed. The results showed that: First, the central flow core in the pipeline is the main migration carrier of the temporary plugging balls and proppants, low-viscosity liquid performs differences when inflowing at various perforation holes. The settlement and plugging in downstream cannot be effectively improved while the upstream without balls’ settlement. Second, due to the fluid resistance, the mean velocity of temporary plugging balls decreases and balls spread along the casing wall while the interaction force can be ignored. Under different displacement, the temporary plugging balls’ migration speed has a relatively stable value, the displacement of 5 m3/min is the critical value for the effective setting of temporary plugging balls. Thus, most of the micro-seismic events after ball-addition were concentrated in the upstream clusters, the impact scope of the micro-seismic events of 6-clusters is greater than that of 8-clusters perforation. After ball-addition in 6-clusters, the key effect is to improve the complexity of the microfracture network, while in 8-clusters to improve SRV (simulated reservoir volume) for the beginning first 4 clusters. So that is, increasing the number of clusters will lead to an inadequate microfracture length extension and only SRV (simulated reservoir volume) near the wellbore zone was improved.

An integral sliding mode control for the magnetic levitation system based on backstepping approach

Due to their reduced maintenance costs, increased power efficiency and reduced power consumption, the Magnetic Levitation (Maglev) system make a significant contribution to the industrial application. Maglev’s production of electricity (e.g. wind turbines), maglev trains and medical devices (e.g. artificial heart pump magnetically suspended) are typical applications. This paper suggests designing a nonlinear control for the Maglev system model which represented by a third-order model consists of the mechanical (ball position and velocity) and electrical (the current) subsystems. The controller is designed utilizing the Integral Sliding Mode Control (ISMC) and based on the Backstepping approach. The tracking accuracy of the ball position to the desired reference is determined by computing the ultimate boundedness as a function to the controller parameters and that using the Lyapunov function. The numerical simulation results showed the robustness and the efficiency of the proposed controller where the tracking error limited by the computed bound.

Physical Function Of Aged Population Is Predicted By Motor Competence And Physical Fitness

Fitness and cognitive status on aging has been widely studied and well reported on literature. Independence and functioning are decisive in elders life quality. Motor competence has been associated to children physical activity levels and healthy weight status. Whether or not Motor Competence has additional value in promoting physical function on aging is not well stablished. PURPOSE: to investigate the relationship and influence of motor competence, physical fitness and cognitive status on physical functioning, in aged population. METHODS: institutionalized participants were recruited as a convenience sample in three day-care centers (N=283, women N=184, mean age = 82.05±7.70 years). Physical functioning was assessed through self-report using a composite physical function scale. Physical fitness was evaluated with the Senior Fitness Test. Motor competence was evaluated as the proficiency in overarm throw a tennis ball, measuring the ball velocity, and standing long jump. Cognitive performance was assessed with Mini-Mental State Examination test. T test was used to test the difference between women and men in all variables. Pearson correlation between physical functioning, physical fitness and motor competence was performed. Stepwise regression was used to identify the predictor variables of physical functioning. Significance was set at p < 0.05. RESULTS: Men had significant better motor competence and physical fitness results than women. In women, the highest correlation were found between physical functioning and Chair stand (r=0.25), standing long jump (r=0.19) and 2-min step (r=0.19). In men, the highest correlation were found on 2-min step (r=0.30) and overarm throw (r=0.27). Stepwise regression retained the following variables: 2.44 m up-&-Go, standing long jump, and sex (F(3; 212) = 33.73; p < 0.001, R2 = 0.32). Men has an estimate of more 2.162 points in physical functioning than women. Physical functioning is estimate to increased 1 point for every -0.151 s in 2.44 m Up-&-Go, and 1 point for every 0.051 cm in standing long jump. CONCLUSION: Despite having found significant moderate to low correlations in both men and women, it seems that both Motor Competence and Fitness status has important influence on physical functioning.

Relationship Of Baseball Pitching Volume To Performance, Biometrics, And Reactive Hyperemia: A Pilot Study

We recently demonstrated body fat %, fast ball velocity, and RPE were significant predictors of valgus torque in NCAA baseball pitchers. Even though changes in hyperemic-induced limb volume are associated with acute, repetitive pitching performance, possibly indicating approaching dominant elbow soft-tissue risk, no investigation, to our knowledge, has examined relationships between performance, biometric, and throwing-limb volume in collegiate pitchers. PURPOSE: To quantify the relationship between pitching performance, subject biometrics, and hyperemic-induced changes in collegiate baseball pitchers during game-simulated pitching sessions of 40, 80, or 120 pitches. METHODS: Following informed consent, 5 male subjects (x̄ age = 18.8 ± 0.8 years; x̄ BMI = 27.6 ± 1.8; x̄ body fat % = 22.9 ± 6.2; x̄ throwing velocity = 80.4 ± 1.8 mph) were block-assigned to groups of 40, 80, or 120 pitches. Bouts consisted of 10 pitches (~20s between pitches) delivered from an artificial mound with 1-2 mins rest between bouts. HR and RPE were recorded immediately following each 10-pitch bout. A MOTUS sensor and compression sleeve measured elbow valgus torque. A Stalker Sport II Radar Gun measured fastball velocity. Pre-test and post-test upper- and lower-extremity limb girths were measured, signifying reactive hyperemia. Wilcoxon non-parametric testing determined pre- to post-test differences. Pearson correlation identified relationships between variables. Alpha was set at p ≤ 0.05. RESULTS: No group differences were found on any performance, biometric, demographic, or hemodynamic variable. HR (72.6 ± 8.3bpm vs. 97.6 ± 10.0bpm, p = 0.02) and dominant forearm limb girth (29.4 ± 1.5cm vs. 30.9 ± 1.5cm, p = 0.04) increased from pre-test to post-test for subjects combined. Significant correlations were found for: pitching volume & post-test HR (r = 0.90, p = 0.039); post-test dominant upper arm circumference & RPE (r = 0.89, p = 0.042), and; valgus torque % change & pitching volume (r = 0.91, p = 0.031). CONCLUSIONS: Forearm limb girth increased for subjects combined, and; given this metric’s indication of reactive hyperemia, future research focused on elucidating and quantifying the biological components of the tissue (compartments), as well as their contribution to performance- and/or injury-specific outcomes, is warranted.

The Relationship Between Shoulder Range of Motion and Arm Stress in College Pitchers: A MOTUS Baseball Study

Objectives:Overuse injuries in overhead athletes are becoming more prevalent, with an unclear relationship between shoulder biomechanics and medial elbow symptoms and injury. The purpose of this study was to investigate the relationship of shoulder range of motion to torque across the medial elbow in college pitchers using a validated MOTUS sensor baseball sleeve.Methods:Pitchers were recruited from three local university baseball teams. Exclusion criteria included injury or restricted activity due to pain. They were evaluated in the preseason, within two weeks before their first game of the season. Pitchers completed workload questionnaires and patient reported outcome measurement information system (PROMIS) pain interference (PI), physical function (PF), and upper extremity (UE) surveys. Shoulder range of motion and upper extremity lengths were measured bilaterally. After adequate warm-up, pitchers were fitted with a MOTUS sensor baseball sleeve (Motus Global, Massapequa, NY) and instructed to throw 5 fastballs in a standardized manner off the mound at game-speed effort. The sensor placed at the medial elbow reported elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. The primary outcome was to evaluate the relationship between shoulder range of motion and increased stress across the medial elbow. Additional outcomes evaluated pitcher characteristics, demographics, and outcome scores. Outcomes were assessed via a multivariable model, which controlled for possible covariates.Results:Twenty-eight pitchers were included in the preseason analysis with an average (SD) age of 20.1 (1.3) years and playing experience of 15.3 (1.8) years, 2.5 (1.2) of those years at collegiate level. The dominant shoulder demonstrated decreased internal rotation (54.5+/-10.6 vs 65.8+/-9.1) and increased external rotation (ER, 94.1+/-10.4 vs 88.4+/-9.2) relative to the non-dominant side (p < 0.001), while total rotational range of motion (TRROM) was significantly decreased in the dominant arm (148.6+/-12.4 vs 154.1+/-10.6, p < 0.001). The average glenohumeral internal rotation deficiency (GIRD) was 11.3 (9.87) and average external rotation gain (ERG) was 5.71 (8.8). External rotation was found to be a predictor of arm stress, with an increase in 0.35 Nm of elbow torque for every degree increase in ER (beta = 0.35+/-0.06, p = 0.003); there was moderate correlation between ER and arm stress (r = .45, P<.001). Pitchers demonstrated significantly greater arm stress with the following shoulder ROM measurements: GIRD < 20 as compared to greater than 20 degrees (46.6 +/- 0.5 versus 43.5 +/- 1.1, P=.011), ERG greater than 5 as compared to < 5 degrees (47.4 +/- 0.7 versus 45.1 +/- 0.6, P=.014), and loss of total rotational ROM less than 5 as compared to > 5 degrees (46.6 +/- 0.5 versus 43.6 +/- 1.1, P=.013). Multivariate analysis demonstrated significant predictors of PROMIS PF and UE scores were arm stress, ERG, and GIRD (p<0.05), while increased PROMIS PI scores were predicted by increased ERG and GIRD (p<0.05).Conclusion:We found medial elbow stress, arm speed, arm slot, and shoulder rotation as measured by the MOTUS baseball sensor sleeve were influenced by rotational adaptations of the pitching shoulder in collegiate throwing athletes prior to their season. Likewise, arm stress and shoulder rotational adaptations were reflected as predictors of PROMIS PF, UE, and PI scores.

Temporally Coupled Coordination of Eye and Body Movements in Baseball Batting for a Wide Range of Ball Speeds.

We investigated the visuomotor strategies of baseball batting, in particular, the relationship between eye and body (head and hip) movements during batting for a wide range of ball speeds. Nine college baseball players participated in the experiment and hit balls projected by a pitching machine operating at four different ball speeds (80, 100, 120, 140 km/h). Eye movements were measured with a wearable eye tracker, and body movements were measured with an optical motion capture system. In the early period of the ball's flight, batters foveated the ball with overshooting head movements in the direction of the ball's flight while compensating for the overshooting head movements with eye movements for the two slower ball speeds (80 and 100 km/h) and only head rotations for the two faster ball speeds (120 and 140 km/h). After that, batters made a predictive saccade and a quick head rotation to the future ball position before the angular velocity of the ball drastically increased. We also found that regardless of the ball speed, the onsets of the predictive saccade and the quick head movement were temporally aligned with the bat-ball contact and rotation of the hip (swing motion), but were not correlated with the elapsed time from the ball's release or the ball's location. These results indicate that the gaze movements in baseball batting are not solely driven by external visual information (ball position or velocity) but are determined in relation to other body movements.

Time analysis of throwing motions to second base by baseball catchers: Comparison of three throwing motions

The purpose of this study was to investigate a baseball catcher’s throwing time to second base using three throwing motion types. The subjects were professional ( n = 4) and college ( n = 12) baseball catchers. Two high-speed cameras were set to capture the throwing motion, while one was set to capture the net on second base. The throwing time of quick throw (throwing motion to release the ball immediately after catching the ball rather than usual throwing motion) was significantly shorter than those of usual throw (throwing motion used during games and practice) and fast ball throw (throwing motion to increase the ball velocity than usual throwing motion). From this result, it became clear that quick throw is the optimal throwing motion when judged by time. Thus, with respect to correlations between variables, there were significant positive correlations between throwing and motion times (usual throw: r = 0.760; fast ball throw: r = 0.719; quick throw: r = 0.767), and between throwing and airborne times (usual throw: r = 0.784; fast ball throw: r = 0.744; quick throw: r = 0.806), for all three throwing motions. However, negative correlations were shown between throwing and release times in usual throw and fast ball throw. The results suggest that, to shorten the throwing time, it is necessary to shorten the hold and stride times and to improve the ability to throw the ball as fast as possible with a shorter motion time.