• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.1-6
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• 2020

Objective: The incidence rate of elbow ulnar collateral ligament injuries is dependent on the throwing speed or pitching type, especially in adolescent baseball players. However, mixed results have been reported due to a lack of controlled biomechanical analysis. Thus, the purpose of this study was to investigate the biomechanical analysis of the elbow in relation to throwing speed and pitching type. Method: Four overhead type high-school baseball players were recruited for this study. The participants were asked to throw balls with different types of pitch and speed. While the throwing speeds were measured, each pitching moment of the elbow was recorded. Descriptive statistics, frequency analysis, mean comparison analysis, and Pearson's correlation analysis were performed in order to examine differences in peak varus and valgus moment during pitching motion in the elbow in all throwing speed and pitching types. Results: There was no significant difference in physical characteristics, throwing speed, and momentum variability among all players. The mean varus moments were 44.38±1.55 Nm, 48.83±1.66 Nm, and 48.94±0.95 Nm, and the moment gaps between varus and valgus were 7.36±3.25 Nm, 7.44±2.02 Nm, and 7.36±2.62 Nm in fastball, curveball, and slider ball, respectively. The varus moment was higher in the curved and slider balls than in the fastballs, and there was no significant differences between the varus moments regarding the pitching type. However, the increase in valgus moment and decrease in moment gap according to throwing speed was significantly increased in the slider ball (r=0.718 and -0.591, respectively). Conclusion: The possibility of elbow injury caused by the valgus moment or moment gapincreases more rapidly in slider balls as the speed increases. Based on our results, appropriate pitching guidelines should be suggested to prevent ulnarligament injuries, especially in adolescent baseball players.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.442-447
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• 2017

The purpose of this study was to establish norm-referenced criteria for the isokinetic strength of the elbow joint in Korean high school baseball players. Two hundred and one high school baseball players participated in this study, none of whom had any medical problem with their upper limbs. The elbow flexion/extension test was conducted four times at a speed of $60^{\circ}/sec$. The HUMAC NORM (CSMI, USA) system was used to obtain the values of the peak torque and peak torque per body weight. The results were presented as norm-referenced criterion valuesusing the 5-point scale of Cajori which consists of five stages (6.06%, 24.17%, 38.30%, 24.17%, and 6.06%). In the results of this study, the peak torques of the elbow (flexor and extensor?) at an angular velocity of $60^{\circ}/sec$ were $37.88{\pm}8.14Nm$ and $44.59{\pm}11.79Nm$, and the peak torque per body weight of the elbow (flexor and extensor?) were $50.06{\pm}8.66Nm$ and $58.28{\pm}12.84Nm$, respectively. The reference values of the peak torque and peak torque per body weight of the elbow flexor and extensor were setat an angular velocity of $60^{\circ}/sec$. On the basis of the results analyzed in this study, the following conclusions were drawn. There is a lack of proper studies on the elbow joint strength, even though the most common injury in baseball players occurs in the elbow joint. Therefore, we need to establish a standard muscle strength in order to prevent elbow joint injuries and improve their performance. The criteria for the peak torque and peak torque per body weight established here in will provide useful information for high school baseball players, baseball coaches, athletic trainers and sports injury rehabilitation specialists in injury recovery and return to rehabilitation, which can beutilized as objective clinical assessment data.

• Journal of the Korea Convergence Society
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• v.12 no.10
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• pp.277-286
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• 2021

This study investigated the effect of a 12-week rehabilitation program on the range of motion (ROM) and muscle strength of high school baseball players with shoulder instability. We allocated 12 players with shoulder instability to the rehabilitation group and 13 players without shoulder instability to the normal exercise group. Covariate analysis (ANCOVA) was performed to assess the ROM of the internal (IR) and external (ER) rotational joints before and after participating in the 12 weeks of rehabilitation, and two-way ANOVA was performed to assess isokinetic muscle strength. The statistical significance level was set at p<.05. The IR ROM of the dominant (D) shoulder with instability and non-dominant (ND) shoulder was significantly increased before and after the rehabilitation program. The total ROM of the D shoulder with instability significantly increased after rehabilitation. IR isokinetic strength significantly improved at an angular velocity of 180°/s after rehabilitation. These results indicate that the rehabilitation program used in this study could be effective in improving ROM and muscle strength in patients with shoulder instability. However, due to the limited results, additional research on the premise of extending the rehabilitation period is necessary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.224-229
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• 2019

This study was undertaken to provide correct posture guidance and reference material for sports injury and injury prevention programs, by analyzing body alignment and plantar pressure distribution in high school baseball players. Totally, 32 subjects were enrolled for the study. Body alignment was measured from the trunk imbalance, kyphotic angle, lordotic angle, pelvic tilt, and pelvic torsion. Foot pressure was measured from the left maximum pressure, right maximum pressure, left weight, and right weight. The mean and standard deviation of the measured factors were calculated and tabulated, and the correlation between body alignment and foot pressure distribution was analyzed using Pearson's correlation analysis. All statistical significance levels were set at 0.05. Body alignment and foot pressure distribution show a positive correlation between the lordotic angle of lumbar spine and the left maximum pressure. There was no correlation between trunk imbalance, kyphotic angle, lordotic angle, pelvic tilt, pelvic torsion, and the left·right weight distribution and the left·right maximum pressure of each foot. Results of this study determined that the increase of the lordotic angle of lumbar spine results in more force on one side of the foot, thereby increasing the maximum pressure. We believe our data could be a reference for exercise programs on physical alignment and plantar pressure distribution of athletes.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.87-92
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• 2018

Objective: The purpose of this study was to investigate the factors affecting two kinds of bat swing behavior through kinematic analysis. Method: A total of 32 high school baseball players participated in this study. The ball was placed on the tee-ball in a position where the subject could easily swing and the standard bat swing was performed as quickly and as accurately as possible using aluminum bats and wooden bats. Results: The aluminum bat showed a rapid swing speed of about 1.79 m/sec compared to the wooden bat. The speed of the batted ball was found to be significantly greater for the aluminum bat than for the wooden bat. In addition, although the difference between the shoulder-pelvis rotation angle according to the type of bat was not indicated, there was a statistically significant difference between the aluminum bat and the wooden bat in terms of the rotational angular velocity. Conclusion: Even though the results can explain the difference between the bat swing speed and the speed of the batted ball depending on the bat's material, it is difficult to explain the difference depending on the type of bat at the shoulder-pelvis rotation angle. However, shoulder-pelvic rotation angular velocity appears to be higher for the aluminum bat, and the differences in the type of bat is considered to be related to the batting swing factor.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.405-411
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• 2017

The purpose of this study was to identify the color that you want the pitcher glove hit impact on the intensity of the other. The color of the glove pitcher was set to black, orange, beige three kinds analyzed the concentration of the batter accordingly. Subjects of this study were 15 people targeting high school baseball players in Daejeon, through a pre- test and vision test color blind players were selected with no visual problems. After the blow of the experiment was used to color the glove Nideffer is modified to fit and complement the six subscales B-TAIS. As a result, when wearing a colored glove that contrasts with the color of the ball, the batter's concentration was increased. Hopefully, research will take place using the ball skill and equipment of various pitchers.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.5 no.2
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• pp.81-88
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• 2012

Purpose: To evaluate the ultrasonographic (US) findings in both shoulders of asymptomatic high school overhead athletes and compare with healthy control. Materials and Methods: 33 individuals (age: $17.5{\pm}1.4$ years) participated in this study. We recruited two groups of high school male athletes, 13 baseball and 10 volleyball players without shoulder pain for recent 6 months as well as one control group of 10 untrained healthy high school students who were age-matched. Ultrasound measurements of thickness of biceps and supraspinatus tendon and acromio-humral distance (AHD) at 0o abduction were taken in dominant and nondominant shoulders. Results: On US examination, subacromial bursa effusion was observed in 5 of the dominant shoulders and in 1 of the nondominant shoulder of 23 overhead athletes and in none of the asymptomatic controls. The thickness of the biceps and supraspinatus tendons and AHD in both shoulders were significantly greater in the athletes than in the controls (P<0.05). We also found that the thickness of the biceps and supraspinatus tendon and AHD of the dominant shoulder were significantly greater than the non-dominant shoulder in overhead athletes (P<0.05), but there were no differences between baseball and volleyball players. Conclusion: Subacromial effusion could be found even in the asymptomatic stage overhead athlete and the thickness of the biceps and supraspinatus tendons and AHD were significantly greater in the overhead athletes than in the healthy controls. Our data is useful reference guide for the ultrasonographic diagnosis of shoulder pathologies occurring in overhead athletes.

• Clinics in Shoulder and Elbow
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• v.25 no.3
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• pp.188-194
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• 2022

Background: Medial elbow laxity develops in throwing athletes due to valgus forces. Medial elbow instability in professional, collegiate, and high school athletes is well documented; however, the medial elbow of young throwing athletes has received less attention. This study investigated the medial elbow and common flexor tendon during applied elbow valgus stress of youth baseball players. Methods: The study included 15 participants. The medial elbow width and thickness of the common flexor tendon were measured on ultrasound images. Results: No significant side differences in medial elbow width or common flexor tendon were found at rest or under applied valgus stress. At rest, the medial elbow joint width was 3.34±0.94 mm on the dominant side and 3.42±0.86 mm on the non-dominant side. The dominant side increased to 3.83±1.02 mm with applied valgus stress, and the non-dominant side increased to 3.96±1.04 mm. The mean flexor tendon thickness was 3.89±0.63 mm on the dominant side and 4.02±0.70 mm on the non-dominant side. Conclusions: These findings differ from similar studies in older throwing athletes, likely because of the lack of accumulated stress on the medial elbow of youth throwing athletes. Maintaining elbow stability in young throwing athletes is a vital step to preventing injury later in their careers.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.179-183
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• 2020

Seligman argues that an optimistic athlete wins based on a study of US professional baseball and professional basketball players.(trans. Choi, 2008). So, the purpose of this study was to investigate whether optimism can predict the performance of badminton youth representatives. 60 high school students were divided into two groups according to their performance. We used the revised Life Orientation Test (LOT-R) developed by Scheier, Carver and Bridges(1994) and translated into Korean version by Shin Hyun-sook(2005). For this study, the data were analyzed by frequency analysis, reliability analysis, and independent t - test. As a result, there was a statistically significant higher level of optimism in the excellent group than in the non-excellent group. So, in order to improve sports performance, we need psychological skills training that can improve optimism as well as physical training and skills training.