PURPOSE The purpose of this study is to analyze the biomechanical variables involved in ballet dancers’ ankle muscle imbalance when performing relevé movements. METHODS The subjects of this study (n=14, age: 22.29±1.73 years old, height: 161.4±5.06cm, weight: 51.88±7.51kg) were 14 ballet dancers with 9 years of experience. Based on the reciprocal muscle strength ratio, the dancers were divided into the following groups: Close to the normal value (RMIS) and far from the normal value (RMIB) using the maximum values of plantar flexion and dorsiflexion of the ankle joint using an isokinetic measurement equipment (60°/sec). RMIB). The biomechanical variables, namely the ankle joint movement and ground reaction force, were subsequently measured. SPSS 26.0 was used for data analysis and independent t-test was used for statistical verification. RESULTS The ground reaction force in the Z (vertical) direction based on the ankle joint muscle strength imbalance of ballet dancers was significantly lower in the RMIB group. In addition, although it was not a statistically significant difference, the plantar flexion movement was lower in the RMIB group, and there was a significant difference in the generation of ankle joint movement in the Z direction. CONCLUSIONS In conclusion, in order for a ballet dancer to efficiently utilize the force generated from the supporting leg when performing a movement, ankle imbalance must be taken into consideration when training.
PURPOSE The purpose of this study was to compare the dynamic postural control of youth athletes with and without a history of lateral ankle sprains. METHODS Twenty-eight youth athletes (14 lateral ankle sprain, 14 healthy control) participated in this study. All participants answered the Foot and Ankle Ability Measure questionnaire and were subject to the Star Excursion Balance Test (SEBT) for dynamic postural control evaluation to collect the joint angles of the lower extremity, a center of pressure (COP) path, and COP velocity. Independent sample t-test or Mann-Whitney U-test were performed to analyze the difference between the groups. RESULTS The lateral ankle sprain group (LAS) was found to have a long experience in participating in sports, and low Foot and Ankle Ability Measure scores were identified when compared to the healthy control (CON; p<0.05). LAS was observed with a short reach distance, less hip flexion, and dorsiflexion angles during the anterior direction of SEBT when compared to CON (p<0.05). Furthermore, LAS showed a slower anteroposterior and mediolateral center of pressure velocities in the posteromedial aspect of SEBT and a slower anteroposterior COP velocity in the posterolateral aspect of SEBT when compared to that of CON (p<0.05). There were no differences between the groups with respect to the other variables (p>0.05). CONCLUSIONS Based on these results, decreased anterior reach distance of SEBT may be affected by changing the dynamic posture control strategy of the lower extremity joint on the sagittal plane in LAS.
PURPOSE The purpose of this study was to develop a period-based psychological support model for athletes and to establish a system after deducing a psychological support model foreach time period. METHODS In this study, 5 psychological support practitioners were selected as research participants to explore requirements and 4 athletes were selected for the field application of the psychological support model. The requirements for developing the psychological support model were collected through in-depth interviews by the psychological support practitioners. Literature reviews and interviews were conducted to develop the psychological support model. RESULTS The period-based psychological support model consists of orientation, problem exploration, problem clarification, intervention, effect evaluation, and termination. The period of psychological support for athletes was divided into the following: A single-session psychological support, brief psychological support, and seasonal psychological support. The system of period-based psychological support model for athletes is a flow chart that applies the period-based psychological support model from the initiation till the termination of psychological support. CONCLUSIONS The phase of the psychological support model is expected to contribute to the enhancement of the effectiveness of psychological support by establishing a psychological support system for athletes.
PURPOSE This study aimed to analyze the dynamic posture stabilization and kinematic variables between visual feedback and Y-balance training groups during jump-landing. METHODS Thirty-eight male players (age: 22.6 ± 1.12 years, height: 175 ± 3.54 cm, weight: 65.5 ± 5.11 kg) were included in this study, and chronic ankle instability was checked using Cumberland Ankle Instability Tool (CAIT) and Balance Error Scoring System (BESS). They were randomly assigned to the Visual biofeedback (Training group: TG, n = 19) and Y-balance groups (Control group: CG, n = 19) for four weeks. TG performed balance training using the Biodex balance system (BBS) and CG performed training using the Y-balance system. During jump landing, time to stabilization (TTS), force plate (COP, GRF); joint angle and moment were collected and analyzed. All analyses were performed with SPSS 21.0, and Bonferroni was used for repeated measured ANOVA and post-hoc. RESULTS The results indicated that there was an interaction between TG and CG in terms of AP and ML directions of TTS (p < 0.05). AP/ML TTS of the TG for the post-test was smaller than that for CG (AP: p = 0.000; ML: p = 0.046). ML TTS of the TG for post-test was smaller than at pre-test (p = 0.041), and AP TTS of the CG for ankle joint moment (p < 0.05). There was an interaction between TG and CG in terms of dorsiflexion (DF) and plantarflexion (PF) of joint moment (p < 0.05). Ankle moment of the CG for post-test decreased than at pre-test (DF: p = 0.040, PF: p = 0.032), and ankle dorsiflexion moment of the CG for post-test was decreased than at pre-test (p = 0.046). CONCLUSIONS Balance ability was achieved more effectively through visual biofeedback training than Y-balance training. Therefore, we recommend balanced training with visual feedback on chronic ankle instability.
PURPOSE The purpose of this study was to examine the effect of visual color perception on autonomic nervous activity and exercise capacity in healthy male college students. METHODS The subjects who were healthy male college student (n=10) were participated in 4 visual colors using by randomized crossover; clear color group (CG), red color group (RG), blue color group (BG) and green color group (GG). All subjects wore goggles for five minutes prior to the exercise to adjust to color, and they did not take off goggles until recovery after exercise. Significant differences between groups were determined by two-way repeated measures ANOVA. RESULTS As a result of this study, the low frequency (LF) was significantly higher in RG than those in GG. But the high frequency (HF) was significant higher in BG compared to GG. Exercise capacity such as maximum strength, muscle endurance, reaction time, power, agility and aerobic performance did not differ significantly between all groups. CONCLUSIONS Therefore, our findings suggested that perception of the visual color might be change autonomic nervous activity, while don’t influence exercise capacity.
PURPOSE This study aimed to identify the nature of human rights violations experienced by semi-professional athletes in semi-professional sports teams and explored the relevant cases. METHODS For this purpose, 35 semi-professional athletes (20 men and 15 women) from the semi-professional sports teams participated in the study, and data collection was conducted through in-depth interviews and focus group interviews (FGI). The collected data were analyzed using the phenomenological research method proposed by Colaizzi (1978). RESULTS The study summarized the results into five categories, 14 theme clusters and 41 themes. Its inherent structures include ‘first step to becoming a semi-professional athlete: disadvantageous contracts for players,’ ‘unavoidable absolute power: obedience to the coach,’ ‘forced training camp: autonomy and privacy infringement,’ ‘structural problems of the semi-professional sports federation: tyrannized power’ and ‘female players who are in male-oriented society: gender-focused than performance.’ CONCLUSIONS The results of this study provided an understanding of athletes’ human rights violations experienced in semi-professional sports teams. Understanding athletes in semi-professional sports teams through phenomenological research was conducted based on previous studies discussing practical and policy intervention measures.
PURPOSE The purpose of this study was to verify the mediated effect between self-presentation, stress coping, and competitive state anxiety among domestic elite athletes and to identify the intermediate effects of stress coping in the relationship between self-presentation and competitive state anxiety. METHODS The study was conducted with 259 elite athletes. The relationship between self-presentation, stress coping and competitive state anxiety was verified using the SPSS and AMOS. RESULTS The results of this study were as follows. First, Self-presentation affected positively on stress coping. Second, Stress coping affected positively on competitive state anxiety. Third, Self-presentation affected positively on competitive state. Lastly, stress coping mediated significantly the relationship between self-presentation and competitive state anxiety. CONCLUSIONS The result of this study shows that the competitive anxiety of elite athletes depends on the meaning of self-presentation, and the stress coping is deeply related to competitive state anxiety. In conclusion, it was determined that it provided basic data to understand the competitive state anxiety of players in various ways.
Purpose The purpose of this study was to examine the difference and consistency of kinematic variables for each athlete by selecting the official records of the world's elite female triple jumpers to evaluate the performance level. Methods Three athletes who won the prizes at the World Championships Daegu 2011 Women's Triple Jump were selected as the study subjects, and only the successful trials were used for analysis. Pearson's correlation analysis was conducted with the kinematic variables in the hop, step, and jump phase, respectively. Also, kinematic variables with statistically significant correlations between braking time and pushing time and related variables were described separately. The duty factor and support factor for the hop, step, and jump of support phases were calculated. Results The successful trials rate were 66.7% for Olha, 50% for Olga, and 83.3% for Caterine. In the last three stride distances of the approach run, Olha and Caterine had a “medium-long-short” pattern and Olga had a “long-short-medium” pattern. There was no difference in the duty factor value between hop and jump phases in the ‘hop-dominate’ technique type, but there was a difference in the jump phase in the ‘balance’ technique type, and the duty factor value in the step of both technique types was greater than that of hop and jump phases. As for the percentage of the support factor, Olha and Caterine had a characteristic that the percentage of braking time in step and jump phases was opposite. On the other hand, Olga had the same percentage for the hop and step phase, and a smaller percentage for the jump phase. Conclusion To increase the accuracy of the board touch-down, maintain a certain last stride(1SL) depending on the technique type. This consistency of the approach run increases reduces distance loss on the take-off board and increases the successful rate of each trial. The duty factor can judge both the performance level and the technique type of triple jump, and the support factor is a variable that can classify the technique types of hop, step, and jump phases. If both the relative time required for the triple jump and the variability of the support time(braking and pushing) for each phase are constant, the difference in records by trial will be small.
Purpose This study aimed to investigate the effects of acute cold stress (10℃, 0℃) compared with ordinary temperature (20℃) on exercise performance and physiological response at rest and during exercise. Methods A total of 10 healthy men (21.55 ± 2.16) were selected. In each environmental condition (20℃, 10℃, 0℃), the three testing order was randomly selected at crossover, and there was a week interval between the graded exercise test (GXT). On the testing day, they remained resting for 30 min in each environmental condition. Dependent variables (body temperature, energy metabolism parameters, skeletal muscle oxygenation profiles, and exercise performance parameters) were measured at rest and during GXT. Results In body temperature, at each environmental condition, there was a significant decrease (p<.05) at 10℃ and 0℃ compared with 20℃ after exercise, and in the difference depending on the environment at rest. After exercise, the body temperature significantly decreased (p<.05) in proportion to the decrease in temperature. There was no difference in heart rate and blood lactate level in energy metabolism, and the respiratory exchange ratio was significantly higher (p<.05) at 0℃ than 20℃. Minute ventilation (VE), oxygen uptake (VO2), and carbon dioxide excretion (VCO2) were significantly lower (p<.05) at 0℃ than 20℃ and 10℃ at various exercise load. All skeletal muscle oxygenation profiles did not show significant changes at rest and during exercise. In exercise performance, maximal oxygen uptake was significantly lower (p<.05) at 0℃ than 20℃, and exercise time to exhaustion was also significantly lower (p<.05) at 0℃ than 20℃ and 10℃. Conclusion Acute cold stress induces deterioration of exercise performance via a decreased body temperature and an increase in VE, VO2, and VCO2 during the same exercise load. In addition it was confirmed that this phenomenon was more prominent at 0°C than at 10°C when compared to 20°C.
Purpose This study was to analyze and compare series of muscle activities during plank exercises with use of togu-jumper. Methods Ten male subjects (age 26.9±1.7 yrs, height 172.2±5.7 cm, weight 66.5±7.5 kg) who have no musculoskeletal disorder with one's upper or lower limb were selected as subjects. To analyze and compare series of muscle activity, five of surface EMG electrodes were attached to the upper rectus abdominis (URA), lower rectus abdominis (LRA), external abdominal oblique (EO), erector spinae (ES) and gluteus maximus (GM). Each subject did plank exercise on stable support surfaces (normal surfaces) and unstable support surfaces with the togu-jumper. For each dependent variable, one-way ANOVA with repeated measures were performed with significance level p<.05. Contrasts were performed to execute post tests for results with statistical significance. Results The study showed that the average IEMG values of URA and LRA increased in Upper (Togu-jumper used upper limb) compared to normal surfaces. This is perhaps because the effects of URA more than any other muscles for body stability. Furthermore, the peak IEMG values of LRA increased in Upper and Lower (Togu-jumper used lower limb) compared to normal surfaces. In addition, peak IEMG values of EO increased in Upper compared to Normal. This may have resulted due to momentary strong muscle activity in LRA and EO to correct body posture and balance. Therefore, using Togu-jumper on upper limb maximizes the performance of core training in plank exercise. Conclusions The study may be further applied to a method for effective training. It is considered that research and analysis has to be further done on modified plank exercise. Additionally, it is necessary to analyze not only global muscle but also local muscle, as a comprehensive research, to suggest ideal method for plank exercise.
