University Players Research Articles

Cavum Septum Pellucidum in Former American Football Players: Findings From the DIAGNOSE CTE Research Project.

Exposure to repetitive head impacts (RHI) is linked to the development of chronic traumatic encephalopathy (CTE), which can only be diagnosed at post-mortem. The presence of a cavum septum pellucidum (CSP) is a common finding in post-mortem studies of confirmed CTE and in neuroimaging studies of individuals exposed to RHI. This study examines CSP in living former American football players, investigating its association with RHI exposure, traumatic encephalopathy syndrome (TES) diagnosis, and provisional levels of certainty for CTE pathology. Data from the DIAGNOSE CTE Research Project were used to compare the presence and ratio of CSP in former American football players (n = 175), consisting of former college (n = 58) and former professional players (n = 117), and asymptomatic unexposed controls without RHI exposure (n = 55). We further evaluated potential associations between CSP measures and cumulative head impact index (CHII) measures (frequency, linear acceleration, and rotational force), a TES diagnosis (yes/no), and a provisional level of certainty for CTE pathology (suggestive, possible, and probable). Former American football players exhibited a higher CSP presence and ratio than unexposed asymptomatic controls. Among player subgroups, professional players showed a greater CSP ratio than former college players and unexposed asymptomatic controls. Among all football players, CHII rotational forces correlated with an increased CSP ratio. No significant associations were found between CSP measures and diagnosis of TES or provisional levels of certainty for CTE pathology. This study confirms previous findings, highlighting a greater prevalence of CSP and a greater CSP ratio in former American football players compared with unexposed asymptomatic controls. In addition, former professional players showed a greater CSP ratio than college players. Moreover, the relationship between estimates of CHII rotational forces and CSP measures suggests that cumulative frequency and strength of rotational forces experienced in football are associated with CSP. However, CSP does not directly correlate with TES diagnosis or provisional levels of certainty for CTE, indicating that it may be a consequence of RHI associated with rotational forces. Further research, especially longitudinal studies, is needed for confirmation and to explore changes over time.

Mechanisms of speed-accuracy trade-off in tennis topspin forehand of college players

ABSTRACT This study aimed to elucidate the mechanisms underlying the speed-accuracy relationship in a tennis topspin single-handed forehand groundstroke. Groundstrokes at three different speeds by nine college players were captured, with the variability of the ball landing position evaluated as indices of accuracy. Variabilities of ball launch variables (speed, launch angle, spin, etc.) and conversion ratios from these variabilities to the variability of the ball landing position were quantified. These variabilities and their conversion ratios could be influenced by different efforts exerted to generate ball speeds and different ball trajectories required to hit a target at each speed, respectively. The speed-accuracy trade-off was observed only in the hitting direction. While the variability of the spin axis increased, it had minimal influence on the ball landing position. Conversely, the conversion ratio in the hitting direction of the velocity elevation angle significantly increased, while its variability remained unchanged. Consequently, the geometrical requirements of ball trajectories can be responsible for the speed-accuracy trade-off. Therefore, even skilled players capable of maintaining consistent ball launch variables regardless of the shot speed should deliberately choose a moderately slower ball speed to avoid an inevitable increase in the variability of the ball landing position due to geometrical requirements.

Comparison of physical fitness level among different competition categories in women's basketball

Acquiring good levels of physical fitness in women's basketball is crucial for success in this complex sport. Thus, the objective of the research is to compare the level of physical fitness in women's basketball between different competitive categories through a systematic review. For this purpose, four databases were consulted (Google Scholar, PubMed, Scielo and LILACS) in Portuguese, Spanish and/or English, in which 32 primary scientific articles were found on physical fitness in women's basketball in the competitive categories and 51 manuscripts complementary secondary about the theme. Physical fitness indicators are divided into anthropometric, metabolic and neuromuscular. Each indicator has a series of variables whose sum will allow us to understand the athlete's actual physical fitness status. The physical training of female players follows the same guidelines as male athletes, but three aspects deserve attention when prescribing programs: menstrual cycle, eating disorders and bone mineral loss. In addition, cardiovascular and neuromuscular characteristics distinguish genders and interfere with physical fitness gains. In general results, professional basketball players presented better averages in the group of indicators (63.1%), followed by formative (21.0%), college (10.5%) and semi-professional (5.26%) players. Finally, it was evident that as female players progress in chronological age, they mature biologically and acquire training support, advancing between the competitive categories. In this way, your physical fitness comes to denote improvement. However, there is a large individual biological variability that impacts the average numbers between the indicators.

A multivariate regression analysis of a comprehensive rehabilitation program and performance improvement in young female volleyball players

Purpose: This study aimed to investigate the efficacy of a comprehensive rehabilitation program tailored for college female volleyball players in India, specifically focusing on its impact on vertical jump performance. Material and Methods: Twenty-seven female college volleyball players participated in the study, undergoing a preseason rehabilitation program comprising various exercises targeting strength, power, stability, agility, and flexibility. Pre- and post-rehabilitation assessments were conducted to evaluate changes in vertical jump height using a Vertec vertical jump measuring device. Statistical analysis included multivariate regression analysis and paired t-tests. Results: The multivariate regression analysis revealed significant positive associations between several rehabilitation components, including squats, depth jumps, and plyometric circuits, and improved vertical jump height (p < 0.01). Paired t-test results indicated a significant increase in vertical jump height post-rehabilitation (p < 0.0001), with a mean difference of 4.863 cm. Strong positive correlations were observed between baseline and post-rehabilitation vertical jump measurements (r = 0.9629). Conclusions: The findings demonstrate the effectiveness of the comprehensive rehabilitation program in enhancing vertical jump performance among college female volleyball players in India. By targeting multiple facets of physical fitness and movement quality, the program facilitated significant improvements in explosive lower body strength and power, essential for volleyball performance. These results underscore the importance of tailored rehabilitation interventions in optimizing athlete capabilities and achieving success on the volleyball court.

Poster 397: Orthopaedic Injury Analysis Among Male and Female High School and Collegiate Aged Soccer Players Presenting to United States Emergency Departments

Objectives: Soccer is the second most played sport in America by participation, with upwards of 12 million players nationally in 2018. A majority of those athletes are adolescents and young adults, with 71% of players falling between the ages of 6 and 24. This study aimed to determine if any injury profile differences exist in the intra- and post-COVID eras between male and female soccer players in both high school and college. Methods: Deidentified Emergency Department data for the years 2020-2022 were queried using the Consumer Product Safety Commission's National Electronic Injury Surveillance System (CPSC NEISS). The raw data was further stratified for a high school age range of 13-17 and a college age range of 18-24. Each of these age ranges were filtered for diagnosis codes 52, 55, 57, and 64 correlating with concussions, dislocations, fractures, and sprains/strains, respectively. The location filter was set to code 9 for a location of sports and recreation. Using the narrative filter, the resultant cases were limited to those that mentioned “soccer”. The identified patient data for each year was collated for total case counts. A Test of Equal Proportions with a Yates Continuity Correction was performed to compare the rate of individual and categorized injuries by sex within each age range and within the same sex between age groups. Results: There were 693, 1371, and 1524 injuries in 2020, 2021, and 2022 respectively, for a total of 3588 injuries. Using statistical weights, this translated to a national estimate of 88,576 soccer-related injuries over that timeframe. Categorically, in each of the three years, males had a higher proportion of fractures when compared to females in the 13-17 age range (p<0.001), while the high school aged females sustained a significantly higher proportion of concussions and sprains/strains (p<0.001). Per specific injury, males experienced a greater rate of clavicular, isolated radial, wrist, nonspecific forearm, finger, and nonspecific lower leg fractures than females aged 13-17 (p<0.001, p<0.027, p<0.001, p<0.001, p<0.025, p<0.029). Conversely, high school aged females were diagnosed with knee and ankle sprains/strains at a higher rate than their male counterparts (p<0.012, p<0.001). There were no significant injury profile differences between college aged male and female soccer athletes. When comparing high school versus college aged males, those in the 13-17 group experienced a larger rate of fractures and concussions, while those in the 18-24 group experienced a greater proportion of dislocations and sprains/strains (p<0.001, p<0.037, p<0.004, p<0.001). College aged males were diagnosed with higher rates of shoulder dislocations, skull fractures, finger fractures, knee sprains/strains, and ankle sprains/strains when compared to their younger counterparts (p<0.001, p<0.007, p<0.001, p<0.001, p<0.05). On the other hand, high school aged male soccer players proportionally sustained more isolated radial, nonspecific forearm, wrist, and pelvic fractures (p<0.001, p<0.001, p<0.002, p<0.002). The only significant difference between high school and college aged females were higher rates of concussions in the 13-17 age group, whereas 18-24 year olds experienced a larger proportion of skull fractures (p<0.01, p<0.01). Conclusions: Since 2020, high school aged males experienced a significantly higher rate of fractures, whereas their female counterparts sustained a larger proportion of concussions and sprains/strains. Within males across all age ranges, higher rates of concussions and fractures were found in adolescents, whereas college males were more often diagnosed with dislocations and sprains/strains. Within females across all ages, high school soccer players experienced a larger proportion of concussions, while college players were diagnosed with a higher rate of skull fractures. Injury profiles between males and females soccer players in college showed no significant differences. Current literature surrounding age and skill-level based soccer injury profiling is limited, with most data reflective of the previous two decades. Our findings allow for insight on the intra- and post-COVID athlete, highlighting potential areas for injury prevention based on sex and age, while underscoring injuries of high clinical suspicion commonly seen in soccer players presenting to US emergency departments.

Team trust as a predictor of collective efficacy in female rugby players

According to Bandura’s (1997) social cognitive theory, “the higher the sense of collective efficacy, the better the team performance”. Bandura also states that collective efficacy is greater than the sum of its individual self-efficacies due to it being influenced by other cognitive factors, including trust (1986, 1997, J Cog Psychother, 13, 158-166). Therefore, the purpose of this study was to investigate the influence of team trust on the construct of collective efficacy within a sport context. It is proposed that team trust is an important cognitive factor that may precede the relationship between collective efficacy and group performance. With institute ethical approval (BREO:33249-A-Nov/2023-47988-1), 21 female college rugby players voluntarily completed the four factor Team Trust Scale (Costa & Anderson, 2011. Eur J Work Org Psych, 20, 119-154) and the five factor Collective Efficacy Questionnaire for Sport (Short, Sullivan. & Feltz, 2005, Meas Phys Ed Ex Sci, 9, 181-202) to measure the correlation between levels of team trust and collective efficacy and determine if team trust is indeed a valid predictor of collective efficacy. Linear regression analyses were conducted and correlation coefficients calculated using Pearson’s correlation. It was predicted that a positive correlation would be shown between the two constructs and that team trust is a significant predictor of collective efficacy. Assuming a positive hypothesis, the study recommends that rugby teams and interdependent sport teams, generally, should develop a high-quality environment of trust both on and off the pitch, given its relationship with collective efficacy and subsequent impact on performance. Relatively little research has been carried out into the effect of intrateam trust within sport and, therefore, this study serves to widen the exploration of this construct and its impact on other social constructs such as collective efficacy and their impact on team performance.

Differences in shoulder function among badminton players broken down by age and sex

BackgroundImproving the understanding of shoulder function for badminton players would develop injury preventive programs. However, no studies on shoulder function reference parameters of badminton players when controlling for age and sex have been found. ObjectivesTo examine the differences in shoulder function between elementary school-age badminton players and university badminton players using shoulder range of motion. DesignCross-sectional study. SettingTesting at elementary school and university. Participants67 players (7-12 year-old players and 18-22 year-old players) without shoulder injury experience. Main outcome measuresShoulder range of motion (ROM) included internal rotation (IR), external rotation (ER), and total ROM (TROM). ResultsSignificant differences in shoulder IR of both sides (dominant: 97.67° vs 77.78°, p < 0.001; nondominant:104.70° vs 88.89°, p < 0.001), dominant ER (126.30° vs 115.98°, p = 0.013), TROM of both sides (dominant: 222.97° vs 193.76°, p < 0.001; nondominant: 222.90° vs 200.10°, p = 0.001), and TROM loss (-0.06° vs 6.34°, p = 0.047) existed between elementary school-age and university players. Significant differences in IR of both sides existed between male elementary school-age and university players (dominant: 98.38° vs 72.50°, p < 0.001; nondominant: 106.72° vs 83.99°, p < 0.001) as well as in female players (dominant: 95.25° vs 82.84°, p = 0.007; nondominant: 103.01° vs 93.57°, p = 0.035). Additionally, significant differences in IR of both sides (dominant: 72.50° vs 82.84°, p = 0.016; nondominant: 83.99° vs 93.57°, p = 0.012) and TROM of both sides (dominant: 188.24° vs 199.05°, p = 0.025; nondominant: 192.43° vs 207.44°, p = 0.002) existed between male and female university players. ConclusionsCompared with university badminton players, elementary school-age badminton players showed significantly greater shoulder IR and TROM of both sides and dominant ER while significantly smaller TROM loss. However, regardless of sex, no significant differences of bilateral deficit for glenohumeral rotation existed between elementary school-age and university badminton players.

Psychological Impact and Posttraumatic Stress Disorder Symptomatology After Ulnar Collateral Ligament Injuries in Baseball Players.

Significant psychological impact and prevalence of posttraumatic stress disorder (PTSD) have been well documented in patients sustaining anterior cruciate ligament injury. To examine PTSD symptomatology in baseball players after sustaining elbow ulnar collateral ligament (UCL) injury. Cross-sectional study; Level of evidence, 3. Male baseball players of various competition levels (high school through Minor League Baseball [MiLB]) who underwent surgery for a UCL injury between April 2019 and June 2022 participated in the study. Before surgery, patients completed the Impact of Event Scale-Revised (IES-R) to assess PTSD symptomatology. Subgroup analysis was conducted according to level of play and player position. A total of 104 male baseball players with a mean age of 19.4 years (range, 15-29 years) were included in the study; 32 players (30.8%) were in high school, 65 (62.5%) were in college, and 7 (6.7%) were in MiLB. There were 64 (61.5%) pitchers, 18 (17.3%) position players, and 22 (21.2%) 2-way players (both pitching and playing on the field). A total of 30 (28.8%) patients scored high enough on the IES-R to support PTSD as a probable diagnosis, and another 22 patients (21.2%) scored high enough to support PTSD as a clinical concern. Nineteen patients (18.3%) had potentially severe PTSD. Only 4 players (3.8%) were completely asymptomatic. Subgroup analysis revealed college players as significantly more symptomatic than high school players (P = .02), and 2-way players were found to be significantly less susceptible to developing symptoms of PTSD compared with pitchers (P = .04). Nearly 30% of baseball players who sustained a UCL injury qualified for a probable diagnosis of PTSD based on the IES-R. Pitchers and college athletes were at increased risk for PTSD after UCL injury compared with 2-way players and high school athletes, respectively.

Biomechanical Analyses of Scoop in Field Hockey

Field hockey is an Olympic sport played all over the world. Hockey is played with a stick where one requires endurance, agility, balance coordination, and high skill to convert the shot. There are various kinds of skills i.e. hitting, dribbling, scooping, tackling etc. Only scoop was selected for the study in different phases (stance phase, execution phase, follow through phase). Field hockey scoop is the aerial passing by lifting the ball from the ground inserting head of hockey stick under the ball. Scoop plays vital role in competitive field hockey games. The aim of the study was to find out the kinematic difference in the elbow joint, knee joint, and ankle joint. The objective of the study was to find out the angular differences of elbow joint, knee joint, and ankle joint in different phases of delivery of field hockey scoop shot. Researchers hypothesised that there are significance differences in elbow joint angle, knee joint angle, and ankle joint angle during delivering of field hockey scoop shot. Six males inter university players aged from 20-24 years were selected for the study and at least they represented at inter university games /national level. Set of the camera is at 1.10 m in height and 3.70 meters. The focal length is 5.6, the resolution is 1080, and the frame rate is 100 per sec. A Sony FRD-AX700 camera was placed 3.7 meters apart on the right side of the hockey player. Angle of elbow joint, angle of knee joint, angle ankle joint, cadence, stride length, and numbers of frames were analysed using Kinovea 0.9.5 software. This research will help the players to execute scoop after knowing elbow joint angle, knee joint angle, and ankle joint angle. Key Words: Field Hockey, Scoop, Elbow, Ankle, Knee.

Sabermetrics by the sea: Evaluating college players with the Cape Cod Baseball League

From the dawn of the “Moneyball” system of searching for players with undervalued skills, an increasing proportion of players chosen in the Major League draft has come from the collegiate ranks, and while every professional team has an analytics department, the draft remains the last frontier for identifying and acquiring the best prospective players. Thus, it has become more important in recent years to evaluate college players properly, and while players’ statistics during the college season can vary wildly due to differing levels of competition, it is necessary to find a more objective metric for measuring college players’ skills. We propose that the most effective metric for doing so comes from observing players’ performances during the summer, when the variable of strength of schedule can be directly controlled, as players of the same skill level compete against each other. Our study focuses on the Cape Cod Baseball League (CCBL), a prestigious summer league that attracts the most talented college players, from which many players are drafted into the Majors every year. Our reasons for choosing the CCBL are the aforementioned homogeneity of talent; the lack of effects of travel fatigue, as the teams all play in a concentrated geographical area; and the league’s built-in replacement level, as temporary players often fill roster spots for players who had been selected the previous autumn, but whose college teams have advanced to the College World Series or who play on a national team during part of the CCBL season. This replacement level is used to calculate a metric of Wins Above Replacement, which we call cWAR.1

Clinical Outcomes and Tau Pathology in Retired Football Players: Associations With Diagnosed and Witnessed Sleep Apnea.

Obstructive sleep apnea (SA) is common in older men and a contributor to negative cognitive, psychiatric, and brain health outcomes. Little is known about SA in those who played contact sports and are at increased risk of neurodegenerative disease(s) and other neuropathologies associated with repetitive head impacts (RHI). In this study, we investigated the frequency of diagnosed and witnessed SA and its contribution to clinical symptoms and tau pathology using PET imaging among male former college and former professional American football players. The sample included 120 former National Football League (NFL) players, 60 former college players, and 60 asymptomatic men without exposure to RHI (i.e., controls). Diagnosed SA was self-reported, and all participants completed the Mayo Sleep Questionnaire (MSQ, informant version), the Epworth Sleepiness Scale (ESS), neuropsychological testing, and tau (flortaucipir) PET imaging. Associations between sleep indices (diagnosed SA, MSQ items, and the ESS) and derived neuropsychological factor scores, self-reported depression (Beck Depression Inventory-II [BDI-II]), informant-reported neurobehavioral dysregulation (Behavior Rating Inventory of Executive Function-Adult Version [BRIEF-A] Behavioral Regulation Index [BRI]), and tau PET uptake, were tested. Approximately 36.7% of NFL players had diagnosed SA compared with 30% of the former college football players and 16.7% of the controls. Former NFL players and college football players also had higher ESS scores compared with the controls. Years of football play was not associated with any of the sleep metrics. Among the former NFL players, diagnosed SA was associated with worse Executive Function and Psychomotor Speed factor scores, greater BDI-II scores, and higher flortaucipir PET standard uptake value ratios, independent of age, race, body mass index, and APOE ε4 gene carrier status. Higher ESS scores correlated with higher BDI-II and BRIEF-A BRI scores. Continuous positive airway pressure use mitigated all of the abovementioned associations. Among the former college football players, witnessed apnea and higher ESS scores were associated with higher BRIEF-A BRI and BDI-II scores, respectively. No other associations were observed in this subgroup. Former elite American football players are at risk of SA. Our findings suggest that SA might contribute to cognitive, neuropsychiatric, and tau outcomes in this population. Like all neurodegenerative diseases, this study emphasizes the multifactorial contributions to negative brain health outcomes and the importance of sleep for optimal brain health.

Brain morphometry in former American football players: findings from the DIAGNOSE CTE research project.

Exposure to repetitive head impacts in contact sports is associated with neurodegenerative disorders including chronic traumatic encephalopathy (CTE), which currently can be diagnosed only at post-mortem. American football players are at higher risk of developing CTE given their exposure to repetitive head impacts. One promising approach for diagnosing CTE in vivo is to explore known neuropathological abnormalities at post-mortem in living individuals using structural MRI. MRI brain morphometry was evaluated in 170 male former American football players ages 45-74 years (n = 114 professional; n = 56 college) and 54 same-age unexposed asymptomatic male controls (n = 54, age range 45-74). Cortical thickness and volume of regions of interest were selected based on established CTE pathology findings and were assessed using FreeSurfer. Group differences and interactions with age and exposure factors were evaluated using a generalized least squares model. A separate logistic regression and independent multinomial model were performed to predict each traumatic encephalopathy syndrome (TES) diagnosis, core clinical features and provisional level of certainty for CTE pathology using brain regions of interest. Former college and professional American football players (combined) showed significant cortical thickness and/or volume reductions compared to unexposed asymptomatic controls in the hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus, insula, temporal pole and superior frontal gyrus. Post hoc analyses identified group-level differences between former professional players and unexposed asymptomatic controls in the hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus, insula and superior frontal gyrus. Former college players showed significant volume reductions in the hippocampus, amygdala and superior frontal gyrus compared to the unexposed asymptomatic controls. We did not observe Age × Group interactions for brain morphometric measures. Interactions between morphometry and exposure measures were limited to a single significant positive association between the age of first exposure to organized tackle football and right insular volume. We found no significant relationship between brain morphometric measures and the TES diagnosis core clinical features and provisional level of certainty for CTE pathology outcomes. These findings suggested that MRI morphometrics detect abnormalities in individuals with a history of repetitive head impact exposure that resemble the anatomic distribution of pathological findings from post-mortem CTE studies. The lack of findings associating MRI measures with exposure metrics (except for one significant relationship) or TES diagnosis and core clinical features suggested that brain morphometry must be complemented by other types of measures to characterize individuals with repetitive head impacts.

On the Value of a Premium College Football Player: Evaluating the Literature

Over the past decade, the issue of player compensation in college sports has been the subject of several successful legal challenges. Athletes contend that the compensation they receive falls significantly short of the value they generate, attributing this gap to unlawful National Collegiate Athletic Association restrictions. Numerous tools exist in the sports economic literature that estimate the value of college athletes, with an emphasized focus toward premium college football players. In addition to providing updated estimate of player marginal revenue product (MRP), we review past and contemporary methodologies for estimating college player MRPs. We contend that, while presenting some evidence that restrictions on player compensation resulted in the extraction of the majority of the value generated by top college athletes, existing methods leave considerable uncertainty over the magnitude of exploitation.

The enhancement of explosive power contributes to the development of anaerobic capacity: A comparison of autoregulatory progressive resistance exercise and velocity-based resistance training

Background/ObjectivesDue to the character of the taekwondo, the adenosine triphosphate–phosphocreatine system provides the energy for each kick, the glycolytic system supports the repeated execution of kicks, and the aerobic system promotes recovery between these movements and the bout. Therefore, taekwondo athletes require high explosive power and anaerobic capacity in order to carry out sustained and powerful attacks. So, the purpose of this study is to compare the effects of APRE and VBRT on lower-limb explosive power and anaerobic capacity in college taekwondo players. MethodsA total of 30 taekwondo players completed an 8-week training intervention with autoregulatory progressive resistance exercise (APRE; n = 15) and velocity-based resistance training (VBRT; n = 15). Testing included the one-repetition maximum squat, countermovement jump (CMJ), taekwondo anaerobic intermittent kick test (TAIKT), and 30-s Wingate anaerobic test (WAnT). Results(1) Intragroup comparisons revealed significant effects for one-repetition maximum squat, peak power of CMJ (CMJPP), relative peak power of CMJ (CMJRPP), and total number of TAIKT (TAIKTTN) in both the APRE and VBRT groups. The VBRT group exhibited small effect sizes for time at peak power of WAnT (WAnTPPT) and moderate effect sizes for peak power of WAnT (WAnTPP), relative peak power of WAnT (WAnTRPP), and fatigue index of TAIKT (TAIKTFI), whereas the APRE group exhibited small effect sizes for TAIKTFI. (2) Intergroup comparisons revealed no significant effects in any of the results. However, VBRT demonstrated a moderate advantage in WAnTPP and WAnTRPP, whereas APRE had a small advantage in CMJPP and CMJRPP. ConclusionsThese findings suggest that APRE improved explosive power (CMJPP and CMJRPP) more, whereas VBRT improved anaerobic power output (WAnTPP and WAnTRPP) more. Both methods were found to have similar effects in improving the anaerobic endurance (WAnTPPT and TAIKTTN) and fatigue index (power drop of WAnT and TAIKTFI).

The Effects of Scapular Stability Training on Serve Speed and Accuracy in College Tennis Players from the Perspective of the Kinetic Chain

Background and Aim: In the tennis serve, the scapula serves as the bony connection between the core, spine, and shoulder. It is the main fulcrum of the body's dynamic chain transmission and plays a very important role in the energy transfer process of the upper limb movement. The objective of this research was to study the effect of scapular stability training in the service kinetic chain on the speed and accuracy of the tennis serve. Materials and Methods: 16 college tennis players from Guangzhou Polytechnic of Sports were randomly selected for this study as a sample group, and divided into an experimental group and a control group, with 8 students for each group (4 males and 4 females). The period of training was 8 weeks. After the tennis training class, only the experimental group will perform scapula stability training twice a week (Monday and Wednesday) for 60 minutes each time. This research used literature methods, expert interviews, experiments, and mathematical statistics to conduct experimental research and theoretical analysis on the effects of scapula stability training on the serving speed and accuracy of college tennis players Results: The results showed that 8 weeks of scapula stability training had a significant effect on improving the stability of athletes' scapula. The scapula stability of the control group (6.81±1.09) and the scapula stability of the experimental group (9.45±1.33). Scapula stability training has a significant effect on the serving accuracy of college tennis players. The serving accuracy of the control group (30.38±5.34) and the serving accuracy of the experimental group (35.50±2.67). Scapula stability training has no significant effect on the serve speed of college tennis players. The serve speed of the control group (136.80±23.89) and the serve speed of the experimental group (122.12±35.71). Conclusion: The results showed that scapular stability and serve accuracy in the experimental group were significantly higher than in the control group (p &lt; 0.05). In terms of serving speed, there was no significant difference between the experimental group and the control group (p&gt;.05). Within the experimental group, there were significant improvements in scapular stability, serve accuracy, and serve speed before and after the experiment (p &lt; 0.05).

Should I Stay or Should I Go Pro? Early NFL Draft Entry by NCAA FBS Underclassmen

Some college players face the tradeoff between continuing their education and entering the draft and forfeiting college eligibility. Little empirical research focuses on this “stay or go pro” decision. We analyze early draft entry decisions made by college football underclassmen with remaining eligibility over the 2007/08-2018/19 seasons. Regression results support both the human capital explanation for early draft entry in that players acquiring more human capital in the previous season by playing in more games increases the likelihood of early entry and the option value perspective in that playing on a more successful team increases the likelihood of early entry.

The validity and reliability of the My Jump 2 app for measuring vertical stiffness in male college players.

Vertical stiffness (Kvert) can be used to evaluate sports performance and injury risk in players. The My Jump 2 smartphone application (App), is increasingly being used by researchers, coaches, and players in the competitive sports field. We aimed to analyze the reliability and concurrent validity of the My Jump 2 app for measuring Kvert in male college players. Twenty male college players (10 soccer players, 10 basketball players; age, 20.2 ± 1.3 years old; weight, 76.4 ± 6.0 kg; height, 178.3 ± 4.7 cm) volunteered to take part in this study. Three drop jumps were performed by participants from 30 cm to 40 cm on a force platform and retested after three days. All the jumps were recorded by both the Force platform and the My Jump 2 app. Data obtained from the above two devices were compared using the paired t tests, intraclass correlation coefficient (ICC), coefficient of variation (CV), Pearson product moment correlation coefficient (r), Bland-Altman plots, and one-way regression. There was almost perfect agreement between measurement instruments for the Kvert value (ICC > 0.972, 95% CI = 0.954-0.992, P < 0.01). Almost perfect agreement was observed between evaluators (ICC > 0.989, 95% CI = 0.981-0.997, P < 0.05). Also, the My Jump 2 app showed excellent intra-rater reliability in all participants (ICC = 1.000, 95% CI = 1.000-1.000, P < 0.001). The My Jump 2 showed good variability when measuring Kvert at T1 30 cm (CV = 5.4%), T1 40 cm (CV = 6.7%), T2 30 cm (CV = 5.0%), and T2 40 cm (CV = 10.3%). The test-retest reliability of My Jump 2 was moderate to good at 30 cm (ICC = 0.708, 95% CI = 0.509-0.827); however, it was lower to moderate at 40 cm (ICC = 0.445, 95% CI = 0.222-0.625). Very large correlations were observed between the force platform and the My Jump 2 for Kvert (r > 0.9655, P < 0.001). The My Jump 2 smartphone application showed excellent reliability and intra-rater consistency in measuring Kvert in male college players. While demonstrating excellent intra-rater consistency and strong agreement with force platform measurements, it showed slightly lower reliability at higher jump heights. Overall, the My Jump 2 app is a valid tool for evaluating Kvert in college players with careful consideration of its limitations, particularly at higher jump heights.

A biomechanics-based study of stroke technique in student tennis players

Abstract Studying the hitting technique of student tennis players is of great significance in improving the technical and tactical level of student tennis and promoting the popularization and scientificization of tennis. Since the performance of tennis hitting action recognition depends on the representation of the action, this study utilizes the Gaussian mixture distribution as a statistical distribution of human action data to provide a more accurate description of tennis hitting action. This paper presents the LM skeletal point coordinate fitting method to enhance the structure of the Gaussian mixture distribution-based Hidden Markov Model to capture the act of hitting the ball. In the end, the biomechanical properties of the tennis hitting technique were examined by analyzing the motion images of forehand and backhand hitting techniques of college tennis players. The mean values of the angle between the racket surface and the ground during the forehand stroke and the topspin stroke were 82.96° and 35.95°, respectively, and the speed of the grip point and wrist joint was faster than that of the flat stroke during the topspin stroke. The angles and velocities of the knee, hip, and ankle joints of the lower limbs were faster than those of the open backhand stroke in the closed backhand stroke. The angle and speed are smaller than that of the open backhand stroke, while the angle of the shoulder and elbow joints is larger than that of the open backhand stroke. The tennis action recognition model and algorithm designed in this paper can effectively acquire and analyze the technical characteristics of tennis hitting.

The Effects of a Short Virtual Reality Training Program on Dynamic Balance in Tennis Players.

This study aimed to analyze the effects of a 5 min virtual reality training program (VR) on dynamic balance in tennis players. Fifty-eight college tennis players (mean age 22.9 ± 3.1 years, weight 73.9 ± 10.8 kg, height 176.6 ± 8.4 cm) were allocated to either the control group (placebo) (CG, n = 20) or the right-handed experimental group (RTG, n = 20) and left-handed experimental group (LTG, n = 18), both of which took part in the 5 min VR intervention program. Pre-tests included anthropometric measures and the Y Balance Test (YBT), and the post-test was the Y Balance Test (YBT). Three YBT trials were performed in anterior (ANT), posterolateral (PL), and posteromedial (PM) directions. After the training intervention, in the right-handed experimental group (RTG), significant differences were observed for two variables: anterior reach (right foot) (p = 0.00) and posterior medial reach (right foot) (p = 0.03). In other analyzed variables, there were no significant differences. Additionally, the effect size was small. In the left-handed experimental group (LTG), statistically significant improvements were identified in five out of six analyzed variables: anterior reach (left foot) (p = 0.00), posterior medial reach (left foot) (p = 0.00), posterior lateral reach (left foot) (p = 0.00), posterior medial reach (right foot) (p = 0.00), and posterior lateral reach (right foot) (p = 0.00). The effect size ranged between small and medium. No significant changes were observed in the control group (CG) after the training intervention. Moreover, for all variables, the time*group interaction is determined. Anterior reach (left foot), posterior medial reach (left foot), posterior medial reach (right foot), and posterior lateral reach (right foot) showed significant interactions (F = 3.04, p = 0.05; F = 3.50, p = 0.03; F = 6.08, p = 0.00; and F = 4.69, p = 0.01). The outcome of this study leads us to a further understanding that if a player were to partake in VR activity, it could show a positive effect on their dynamic balance performance.

Shoulder kinetic during pitching in baseball players with scapular dyskinesis

IntroductionShoulder injuries in baseball players cause excessive shoulder load during pitching and scapular dyskinesis (SD). However, the characteristics of pitching kinetics in the shoulder joint with SD are unclear. This study aimed to investigate the effect of SD on pitching kinetics in the shoulder joint of baseball players. MethodSeventy-two college and independent league baseball players participated in the study. The pitching motion was measured using an 18–camera motion-capture system. SD was classified into four types (I–IV) using the scapular dyskinesis test (SDT). The pitching kinetics data were analyzed. ResultsThe agreement of SD in this study was 56/72 (77.8%). SD were classified into 31 abnormal group (type I–Ⅲ) and 25 control group (type Ⅳ). Three participants with measurement failure during the pitching motion analysis were excluded from the analysis. The abnormal group showed a larger maximum value of the glenohumeral normalized anterior joint force than the control group. ConclusionsThese results suggest that an increase in GH anterior force during pitching causes an excessive increase in external rotation of the GH with an insufficient posterior tilt of the scapula with SD. Therefore, baseball pitching with SD may involve shoulder injuries owing to excessive shoulder load during pitching.