• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.109-116
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• 2013

The purpose of this study was to provide fundamental information for the enhancement of performance through kinematic analysis of cornering according to the radius of curve course in short track speed skating. To perform this study, six skaters: three narrow radius players(N, body mass: $56.0{\pm}7.2$ kg, height: $163.7{\pm}5.1$ cm, age: $21.3{\pm}1.5$ yrs) and three wide radius players(W, body mass: $61.0{\pm}9.5$ kg, height: $169.0{\pm}4.4$ cm, age: $20.0{\pm}1.7$ yrs). Three-dimensional motion analysis was performed on the section from the forth block starting to show the change of radius to the sixth block using eight infrared cameras(sampling frequency of 100 Hz for N and W players). The time of push-off was greater for N than for W(p<.05) while the radius of center of mass was greater for W than for N(p<.05). The flexion and extension of knee and hip joint were greater for N than for W(p<.05). The external rotation of left knee joint was greater for N than for W(p<.05). Based on the findings, a small radius by increasing the range of the flexion and extension of knee and hip joint with greater external rotation of left knee joint would be related to more efficient run at curve. It is expected that these results will be useful in developing a training program for enhancing performance of short track speed skating athletes.

• Journal of the Korea Convergence Society
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• v.10 no.2
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• pp.301-307
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• 2019

The purpose of this study is to evaluate the lap time of K-1 sprint competition and compare the records of the best group and the other groups. Based on these data we are willing to provide them on pace control strategies for improving their performances. The analysis was conducted on 12 elite kayak players, measuring the lap time by every interval after dividing the entire 1,000-meter race into 10 sections of 100 meters. We divide the group A, B, C and D based on their final time records. Two-factor repeated measures ANOVA, One-way ANOVA, and correlation analysis were performed. There were no significant lap time differences in the section of first 200m and last 200m between A, B and C. But the C's lap time of 200m~600m were significantly later than group A and B. Non-superior athletes need to establish strategies to reduce lap time in the middle section.

• Korean Journal of Exercise Nutrition
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• v.24 no.4
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• pp.15-23
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• 2020

[Purpose] Lactate is a principal energy substrate for the brain during exercise. A single bout of high-intensity interval exercise (HIIE) can increase the blood lactate level, brain lactate uptake, and executive function (EF). However, repeated HIIE can attenuate exercise-induced increases in lactate level and EF. The lactate levels in the brain and blood are reported to be correlated with exercise-enhanced EF. However, research is yet to explain the cause-and-effect relationship between lactate and EF. This study examined whether lactate consumption improves the attenuated exercise-enhanced EF caused by repeated HIIE. [Methods] Eleven healthy men performed two sets of HIIE, and after each set, 30 min were given for rest and examination. In the 2^nd set, the subjects consumed experimental beverages containing (n = 6) and not containing (n = 5) lactate. Blood, cardiovascular, and psychological variables were measured, and EF was evaluated by the computerized color-word Stroop test. [Results] The lactate group had a higher EF (P < 0.05) and tended to have a higher blood lactate level (P = 0.082) than the control group in the 2^nd set of HIIE. Moreover, blood lactate concentration was correlated with the interference score (i.e., reverse score of EF) (r = -0.394; P < 0.05). [Conclusion] Our results suggest that the attenuated exercise-enhanced EF after repeated HIIE can be improved through lactate consumption. However, the role of lactate needs to be elucidated in future studies, as it can be used for improving athletes' performance and also in cognitive decline-related clinical studies.

• Korean Journal of Applied Biomechanics
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• v.33 no.3
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• pp.101-109
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• 2023

Objective: The aim of this study is to verify the differences in muscle characteristics of elite level swimmers before and after a 2-hour practice session. Method: The study was conducted on 15 elite swimmers. Preliminary measurements for each muscle (Anterior Deltoid, Triceps Brachii, Biceps Brachii, Flexor Carpi Ulnaris) were taken using the MyotonPRO device before training. After approximately 2 hours of training, the same muscle areas were measured again. The collected data was analyzed through descriptive statistics and two-way 2×2 RG·RM ANOVA, and all statistical significance levels were set at α=.05. Results: After analyzing the characteristics of the Flexor Carpi Ulnaris (FCU) before and after training in both proficiency level swimmers (excellent, non-excellent), it was found that the interaction effect of group X repetition in muscle tension (F), muscle stiffness (S), and body recovery time (R) was statistically significant. Secondly, in the analysis of the Biceps Brachii (BB), the main effect of repetition in muscle tension (F), muscle stiffness (S), and body recovery time (R) was statistically significant. Furthermore, the interaction effect of group X repetition in muscle stiffness (S) and body recovery time (R) was statistically significant. Conclusion: The efficient use of FCU and BB suggests that it is an important factor distinguishing the performance of excellent and non-excellent swimmers in swimming. Therefore, if we develop and apply measures to efficiently utilize FCU and BB during training, it can help improve the performance of the athletes.

• Sleep Medicine and Psychophysiology
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• v.21 no.2
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• pp.80-84
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• 2014

Introduction: Sleep has numerous important physiological and cognitive functions that may be particularly important to elite athletes. Sleep deprivation can have significant effects on athletic performance. However, there are few published data related to the amount of sleep obtained by elite athletes. We investigated sleep patterns of Korean women golfers using sleep-related questionnaires. Methods: For this study, 98 Korean university women golfers and 46 age- and sex-matched controls were recruited. All subjects were asked to complete the self-administered sleep questionnaire consisting of questions about habitual sleep patterns (sleep onset time, sleep latency, awakening time in the morning, day time napping time), exercise habits, Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISS), Pittsburgh Sleep Quality Index (PSQI), validation of the Perceived Stress Scale (PSS), and Beck Anxiety Inventory (BAI). Results: The sleep onset time was significantly earlier (pm 23 : $05{\pm}00$ : 52 and 00 : $14{\pm}00$ : 51 ; t = 5.287, p < 0.001), the waking time was later (am 07 : $21{\pm}01$ : 09 and 6 : $35{\pm}00$ : 32; t = -2.715, p = 0.008), the weekday total sleep time was greater ($417.77{\pm}78.18$ minute and $351.52{\pm}77.83$ minute ; t = 4.406, p = 0.001), and the daytime nap time was greater ($77.73{\pm}41.28$ minute and $20.22{\pm}33.03$ minute ; t = 7.623, p < 0.001) in the golf athletes compared to the controls. The PSQI scores were significantly lower, but estimated sleep latency and ESS, ISS, PSS, and BAI scores were not different among the two groups. Conclusion: This study suggests that Korean university women golfers have good sleep patterns resulting in no difference in sleep-related stress compared to age- and sex-matched control students.

• Journal of Korean Orthopaedic Sports Medicine
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• v.4 no.2
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• pp.109-115
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• 2005

Purpose: The purpose of this study was to evaluate the effectiveness of three functional performance tests and one-legged hop test and to establish the reference data of the three functional performance tests of the active young Korean men. Materials and methods: We performed five tests on 40 normal subjects such as one-legged hop test (single hop, triple hop) and the three functional performance tests (carioca test, co-contraction test, shuttle run test). The mean age was 28.4 years. The mean score of Tegner activity scale was 6.2 and Lysholm score 98.2 Mean value and standard deviation were obtained. The correlation of age, height and weight with the results, the relationship between FPT and one-legged hop test and the mean difference between dominant and non-dominant limbs were statistically calculated. Results: All data obtained were normally distributed and there were no significant relationship between age, height and weight. The paired t-test of one legged hop test showed no statistical significance between dominant and non-dominant limbs. The results of one legged hop test had strong relationship with functional performance test. Conclusion; The three functional performance tests can be a useful functional test in ACL-insufficient athletes. Our results can be used as normal reference data of the normal active Korean men.

• Journal of Life Science
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• v.33 no.5
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• pp.436-444
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• 2023

Scientific training, diet, and ergogenic aids are widely used to overcome the limits of humans' physical abilities and to achieve excellent sports records. The adoption of nutritional strategies is important for athletes to perform at their highest level, and one of the main factors determining endurance ability is increased fat metabolism. A ketogenic diet (high fat, low carbohydrates) has thus been proposed as an alternative strategy to maximize fatty acid oxidation during prolonged periods of exercise. However, studies have shown mixed results regarding the ergogenic value of a ketogenic diet. For this reason, exogenous ketone supplements (EKS, ingestible forms of ketone bodies, ketone esters, and/or salts) have been suggested to obtain nutritional ketosis, an acute transient increase in circulating acetoacetate (AcAc) and b-hydroxybutyrate (bHB) concentrations, without limiting carbohydrate intake. Some studies have suggested the beneficial effects of EKS on the performance of endurance exercises by providing an additional fuel substrate for peripheral tissues, such as cardiac and skeletal muscles, sparing carbohydrates/increasing fat oxidation and post-exercise recovery by increasing glycogen resynthesis in the liver/muscle, attenuating protein degradation, stimulating protein synthesis in the skeletal muscle, etc. However, many studies have failed to observe the beneficial effects of EKS as an ergogenic aid. As such, this review summarizes the theoretical basis of, as well as the proposed and proven effects of EKS on exercise performance and recovery to date.

• The Journal of the Korea Contents Association
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• v.8 no.10
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• pp.301-308
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• 2008

The purpose of this study was to investigate the change of physical fitness, MDA, SOD after short-term weight reduction through exercise, food restriction and exhalation of sweat among Taekwondo players. The subjects ten male collage Taekwondo players with excellent practical skills, and more than seven years of experiences. They were asked to reduce about 5% of their body weight in seven days. Physical fitness levels were analyzed through grip strength, muscle endurance, flexibility, power, agility, balance, reaction time and MDA and SOD through blood test. The results of this study were as follows; First, there was no significant change in physical fitness due to short-term weight reduction in muscle strength, muscle endurance, flexibility, power, agility, balance and reaction time. Second, The change of MDA and SOD, resulting from short-term weight reduction did not show significant difference statistically. Therefore, the results of this study indicate that the Taekwondo players' short-term weight reduction of 5% of their body weight did not influence on their athletic performance and physiological capacity. Therefore athletes and coaches should endeavor to take exercise, dietary, and dehydration into consideration when conducting 5% of their body weight reduction in a week.

• Journal of Digital Convergence
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• v.15 no.11
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• pp.497-511
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• 2017

The purpose of this study was to explore players' perception and emotional reaction toward referee's judgment. The participants of this study were six players (three male and three female) in 2016 national team. The results of this study are as follows: First, the differences in referee judgement were dependant on referees' subjective view point, rapid judging capability, qualification and experience. Second, we found that the a referee's judgement less affected match's results. The countermeasures against the adverse referee judgment include excitement, appeal, flow interruption, thought conversion, and concentration. Third, there were many opinions that both the degree of influence of the referee's judgement and the countermeasures was such that athletes were "not affected". In conclusion, the major determinant of players' performance were game strategy and accuracy of skill although the referee's judgement affected player's emotional reaction both in positive and negative ways.

• Journal of the Korea Convergence Society
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• v.11 no.4
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• pp.151-156
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• 2020

The purpose of this study is to design a process for developing wearable sports helmet devices by utilizing IoT server technology, focusing on sports where helmet wear is essential at sports sites. This enables customized training of athletes by continuously accumulating personal biometric information during training, checking players' condition based on data, and informing them of injury prevention and dangerous situations. In addition, the wearable device that can be useful when the training place is likely to damage the physical health due to heat waves or extremes can provide a foundation for improving the performance. Since such technology can be applied not only to the sports field but also to the society such as the industrial field or the underprivileged, it can be expected to be expandable.