• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.127-133
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• 2020

PURPOSE: The study examined the relationship between the knee function score and knee strength and muscular endurance of an elite female handball athletes according to their position in the team. METHODS: Thirty handball athletes participated on the study: 12 front positions, 12 back positions, and five goalkeepers. The knee function score consisted of symptoms, pain, daily activity, sports and recreation, and quality of life. In addition, CSMI (Cybex, USA) was used to measure the strength and muscular endurance of the knee. The muscular strength and muscular endurance were measured at an angular velocity of 60°/s and 180°/s, respectively. RESULTS: The overall items of the knee function score showed a significant difference (p = .017), and goalkeepers had significantly higher scores than the back positions. In addition, significant differences were observed in all five items depending on the position (p ≤ .05). On the other hand, both the flexor and extensor muscles of the knee strength and muscular endurance were not significant. Moreover, there was no correlation between the knee function score and the knee strength and muscle endurance. CONCLUSION: Elite female handball athletes have different knee functions score depending on their position in the team, but the, strength and muscular endurance of the knee were similar for each position. Furthermore, the knee function score showed no correlateion with the strength and muscular endurance of the knee.

• Korean Journal of Applied Biomechanics
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• v.34 no.1
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• pp.34-44
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• 2024

Objective: This study aimed to investigate how the movements occurring during the follow-through phase after releasing an arrow among elite compound archers, are associated with the arrow impact points on the target. Method: Nine elite archers performed consecutive compound archery shooting under conditions identical to actual competitions using their own bows and equipment. Motion capture system and force platform were utilized to record the changes in joint positions and center of pressure, respectively. Principal component analysis was employed to identify the patterns in which multidimensional joint positions and COP changes were organized with horizontal and vertical coordinates of arrow impact points. Subsequently, correlation analysis quantified the relationship between individual variables and the coordinates of arrow impacts on the target. Results: We found a common organizational pattern in which the two axes of the impact point coordinates were grouped into the first two principal components. The movements of the upper and lower limbs following release exhibited opposite patterns in the anterior-posterior axis, with significant correlations observed between the arrow impact points of the horizontal axis and the left shoulder, right elbow, left hip, and both knees. Additionally, the lateral movements induced by the reaction force upon arrow release showed significant associations with the vertical coordinates of the impact points. Particularly, the correlations between the movements of the left shoulder and elbow, as well as the bilateral hip and right knee, were consistently observed among all participants. Conclusion: These findings implied that the post-release movements could significantly influence the trajectory and impact points of the arrows in compound archery. We suggest that a consistent and controlled movement during the follow-through phase may be more beneficial for optimizing shooting accuracy and precision rather than minimizing movements.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.191-202
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• 2004

The batting performance in baseball is a repetitive movement. In order to make the stabilization of posture and the efficient shift of body weight, both the range of stance and stride are important. The previous studies explained that the consistent stride which included the amount of time, stance, and direction were needed. However, the batting performance is frequently changed according to the several speed of ball. Therefore, this study was to analyze the reaction time, the range of stance, the change of stride, and the change of GRF during the batting movement in three kinds of ball speed (120km/h, 130km/h, & 140km/h). Seven elite players are participated in this study. 1. The reaction time of the stride phase was short whereas the time of the swing phase was long according to the increasing ball speed. 2. The range of the stance was wide and the mediolateral direction of the stride was decreased according to the increasing ball speed. 3. In the three kinds of ball speed, the change of body weight was transferred to the center, the rear foot, and the front foot directions. The ball speed of 130km/h showed the high frequency of the suitable batting. At this ball speed, the movement of the body weight was shifted smoothly and the value of the Ground Reaction Force was large enough.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.1-9
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• 2014

The purpose of this study was to investigate the muscle mechanical properties of the pelvic axial pre-rotational movement for the Jireugi in the Taekwondo Juchumseogi stance. Eleven elite Taekwondo Poomsae athletes participated. Each participant performed 5 right hand Jireugi in Juchumseogi stance as fast and strong as possible while their motion was recorded by a 3D motion analysis system and the ground reaction forces by two force plates. The power and work of the muscular group surrounding the waist were analyzed to verify the effect of the stretch-shortening cycle (SSC) theory. The cause of the greater power seems to be the application of the SSC by the muscles surrounding the waist during the preparation phase of the pre-rotation group. For the none pre-rotation group, they only used the concentric contraction of the muscles surrounding the waist. Because the pre-rotation group used the SSC theory, they had the effect of shortening of the range of movement, creating a fast and more powerful rotation, thus anticipating the increase the magnitude of impact.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.11-18
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• 2014

The purposes of this study were to analyze the kinematics and electromyographic variables of the upper extremity for the backhand clear motion according to the type of hitting in badminton. Seven elite male university players were selected as the subjects. Four digital video cameras and Noraxon Telemyo 2400 were used to collect the 3D kinematics and electromyographic data. The results were as follows: 1) in the phase of impact, the time of motion for the overhead backhand clear was the longest, 2) in the event of impact, the distance of step toward X direction was the longest and the distance of step toward Y direction was the shortest for the overhead backhand clear, 3) in the event of backswing, the rotation angles of shoulder and pelvis and the flexion angle of shoulder for the overhead backhand clear were the biggest, 4) the maximum flexion angular velocity of shoulder and the maximum extension angular velocity of elbow for the overhead backhand clear were the biggest, and 5) in the phase of impact, mean EMG of the wrist flexor, triceps, and trapezius muscle for the overhead backhand clear was bigger than that for the underhand stroke and in the phase of follow-through, mean EMG of the wrist flexor and extensor, biceps, triceps, and trapezius muscle for the overhead backhand clear was the biggest.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.165-169
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• 2017

Objective: The Star Excursion Balance Test (SEBT) and Y-Balance Test (YBT) have been commonly applied to measure dynamic postural stability ability. These two tests are utilized interchangeably in various settings. However, they could in fact require different movements to assess dynamic postural stability, as one uses a platform and different measuring techniques than the other. The purpose of this study was to determine if there was a significant difference in the kinematic patterns in physically active population while performing the SEBT and the YBT. Method: Seventy participants performed in the Anterior (AN), Posteromedial (PM), and Posterolateral (PL) directions of the SEBT and the YBT. The kinematics of hip, knee, and ankle in sagittal plane was calculated and analyzed. Paired-sample t-tests were performed to compare joint angular displacement in the ankle, knee, and hip between the SEBT and the YBT. Results: Significant differences in angular displacement at the hip, knee, and ankle joints in the sagittal plane between performance on the SEBT and on the YBT were observed. Conclusion: Clinicians and researchers should not apply these dynamic postural control tasks interchangeably from one task to another. There appear to be kinematic pattern differences between tests in healthy physical active population.

• IMMUNE NETWORK
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• v.5 no.2
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• pp.117-123
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• 2005

The immune response to any stimulus is complex, requiring coordinated action by several types of cells in a tightly regulated sequence. Thus, a physical stress such as exercise may act at any number of points in the complex sequence of events collectively termed the immune response. Although exercise causes many propound changes in parameters of immune function, the nature and magnitude of such changes rely on several factors including the immune parameters of interest; type, intensity, and duration of exercise; fitness level or exercise history of the subject; environmental factors such as ambient temperature and humidity. Although regular moderate exercise appears to be important factor for increasing immunity, Athletes are susceptible to illness, in particular upper respiratory track infection, during periods of intense training and after competition. In addition, in elite athletes, frequent illness is associated with overtraining syndrome, a neuroendocrine disorder resulting from excessive training. Through this paper, we want to investigate the effects of exercise on the immunosuppression such as exercise induced lymphopenia, asthma, anaphylaxis, URT (upper respiratory track), and TB (tuberculosis) infection. and also, we want to suggest a direct mechanism, protection and therapy of exercise induced immunosuppression.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.27-46
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• 2003

The purposes of this study were to determine the functions of actions of the limbs during each of the three support phases of the triple jump and their relationships with the performance of the triple jump. Four elite male triple jumpers were participated as subjects. The statistical analyses used were the Pearson product moment correlation coefficient for establishing relationships and simple regression analyses to determine and compare the relationships between the change of the horizontal velocity and the change of the vertical velocity during different support phases. A level of significance at p<.05 was set. The actions of the arms were responsible for about 25%, 25%, and 30% of the decrease in the horizontal velocity of the whole body center of gravity during the support phases of the hop, step, and jump, respectively. The change in the velocities of the whole body center of gravity due to the actions of the free limbs were significantly related with the whole body center of gravity during each support phase. The action of the support leg was associated with the decrease in the horizontal velocity and the increase in the vertical velocity of the whole body center of gravity during each support phase.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.15-26
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• 2003

This study was conducted to investigate the performance times, CM position and CM speed, pole chord length and pole chord angle, whole body angular momentum(X axis), and grip width in pole vault event according to the event and phase; touch down, pole plant, take-off, maximum pole bending pole straight, pole release, peak height, and foot contact, pole contact, free flight. The pole vaulting of four male elite vaulters including six trial were filmed using two video digital cameras at 60 Hz at 56th national athletic match, and data were collected through the DLT method of three dimensional cinematography. In general the better jumper is, the longer the performance time is. And the greater CM speed is, and the better his transformation ability of CM horizontal speed into vertical speed is. As he uses a longer pole, his grip is higher, and it is a enough for him to rock back his body, so that he pulls and pushes the pole well keeping his hips close to. An greater maximum angular momentum and early positioning of the hips parallel to the bar makes his body far side of the bar and his bar clearance easier. Specially our national jumper needs to have more powerful braking force during foot contact phase, and take his body on the pole after maximum pole bending, and pull and push the pole strongly keeping his hips close to. Also he needs to have stronger muscular strength in order to control the longer pole and use the pole of proper tension more efficiently.

• Korean Journal of Community Nutrition
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• v.3 no.1
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• pp.94-106
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• 1998

Nutrient supplements are often used by athletes as ergogenic aids. This study was done to investigate the use of nutrient supplements, nutritional knowledge and nutrient intakes of athletes. Subjects of this survey consisted of 195 national team athletes. The prevalence of nutrient supplement use among all subjects was 30.3%, and the frequency of use, by decreasing order, was weight lifting, taekwondo and badminton athletes. Sport drinks were the type of nutrition supplement used most frequently and vitamin C was the second one. Major reasons for nutrient supplement use were to improve training performance and to recover from fatigue, to supplement fluid and to control weight. The average score of nutritional knowledge was $19.9\pm{2.5}$ for nutrient supplement users, and $19.8\pm{3.6}$ for nutrient supplement nonusers. Intakes of protein, calcium and niacin of the user were higher than those of the nonuser. This information provided by this study can help sport nutritionists identify nutrient supplement most often consumed by national elite athletes and can aid counselors as they guide athletes towards more healthful nutrition practices.