PURPOSE This study aimed to analyze the differences in ground reaction forces (GRF) and pelvis and trunk kinematic patterns between groups based on ball speed during pitching. METHODS Twenty-nine males were recruited for this study. Participants were categorized based on ball speed into high (HG), medium (MG), and low (LG) ball speed groups. Statistical analysis was performed using one-dimensional statistical parametric mapping (SPM1D) one-way analysis of variance to compare GRF and pelvis and trunk kinematic patterns, followed by Bonferroni post-hoc tests. RESULTS Drive leg anterior and resultant GRF were greater in the HG than in the LG (p<0.001). The posterior GRF of the stride leg in the HG was greater than in the LG (p<0.008). Additionally, the vertical GRF of the stride leg was greater in the HG than in the LG (p<0.003), as was the resultant GRF of the stride leg (p<0.003). CONCLUSIONS The GRF of the drive and stride legs was significantly related to ball speed, indicating that a pitching strategy to maximize the GRF of the drive and stride legs is required.
PURPOSE This study analyzed the effect of dynamic lumbar kyphosis on the biomechnical factors affecting the lumbar joints during deep squats. METHODS Thirty adults in their 20s who had experienced weight training for more than one year participated in this study (age: 23.4±3.5years old, height: 175.3±4.3cm, weight: 75.8±6.5kg, squat single repetition maximum (1RM) weight: 115.3±19.5kg). Under both restricted dynamic lumbar kyphosis (RDLK) and dynamic lumbar kyphosis (DLK), subjects completed one repetition of deep squats at a load of 70% of their 1-RM weight. To verify the consistency of deep squat movements performed under DLK and RDLK conditions, intra-rater reliability was analyzed using intra-class correlation . The biomechnical variables of the lumbar joint were calculated during DLK and RDLK deep squats. Paired sample t-tests (IBM SPSS 27.0, Armonk, New York, USA) were used for statistical verification. RESULTS During the deep squat movement performed in DLK and RDLK conditions, the peak angles of the ankle, knee, and hip joints, the minimum height of the pelvis, and the time and tempo showed statistically high reliability, confirming the accuracy of the movement. The peak flexion angle and moment, left flexion moment, left rotation moment, and compression force factors of the lumbar joint during deep squat were significantly lower in RDLK than in DLK. CONCLUSIONS Restricting lumbar dynamic kyphosis during deep squats is essential for decreasing the risk of lumbar joint injury.
PURPOSE This study sought to analyze the velocity and asymmetry between bilateral lower extremity mechanics according to the load during walking. METHODS A total of 14 adults with right leg dominance participated in this study (Male=7, Female=7). We respectively applied 30% of body weight load carriage on the subjects. Gait characteristics were analyzed with 3-dimensional cinematography and ground reaction force (GRF) system consisted of a center of gravity (COG) velocity, center of pressure (COP) area, leg stiffness, and GRF components. RESULTS Change in velocity of the maximum-minimum COG showed statistically significant in the main effect of load. The 1st anterior-posterior GRF (braking force) and vertical GRF were statistically significant in the main effects of load and bilateral lower limbs. The 2nd anterior-posterior GRF (propulsive force) was statistically significant in the main effect of load. COP area and leg stiffness exhibited statistically significant differences in the main effects of load and bilateral lower limbs. Interaction was observed in the vertical GRF, COP area. Furthermore , one-way variance analysis revealed load main effect had a greater influence on the increase in the magnitude of the vertical GRF and COP area than the asymmetry of bilateral lower limbs. CONCLUSIONS This study revealed the differences in asymmetry between the dominant and non-dominant lower limbs according to the load during walking. These findings may explain the differences shock attenuation and stress mechanisms between the bilateral lower limbs.
PURPOSE This study aims to analyze the effects of injury prevention video feedback on kinetic variables of the knee joint during the cutting maneuver. METHODS Twenty-eight healthy men participated and motion and force data were collected using infrared cameras, a force plate, and a Witty timing system. Paired t-tests were employed for data evaluation using the SPSS 26.0 program. RESULTS Results showed increased abduction and lateral rotation angles of the knee joint at the lower height of the center of mass (COM) (p<. 05). The lateral rotation of the knee joint decreased at initial ground contact (p<.05). Flexion angular velocity increased at initial ground contact after video feedback (p<.05) and decreased at the lower height of COM (p<.05). Abduction angular velocity decreased at the lower height of COM (p<.05), and internal rotation angular velocity was increased on the initial ground contact (p<.05). Maximum ground reaction force for anterior-posterior and medial-lateral directions increased after video feedback (p<.05). Flexion and internal rotation moments increased, and adduction moment also increased (p<.05). CONCLUSIONS In conclusion , video feedback effectively reduced knee load during the cutting maneuver, contributing to injury prevention for the knee joint.
PURPOSE This study explores the factors influencing eco-friendly behavioral intentions during sports spectating and infers the causal structure linking each variable to eco-friendly behavioral intentions. METHODS A total of 364 sports fans participated in the survey that collected data on Knowledge of Climate Change (KCC), Awareness of Climate Change (ACC), Attitude of Climate Change (ATT), Subjective Norm of Climate Change (SN), Perceived Behavior Control of Climate Change (PBC), and Behavioral intention to Reduce Single-Use Plastic (INT) during sports spectating. The validity of the measurement was examined through confirmatory factor analysis. Based on the validated data, latent variables’ average scores were reconstructed as input variables for the Bayesian Network, along with demographic characteristics. RESULTS The results of Bayesian network learning indicated that ACC, ATT, SN, and PBC variables directly influence INT. ACC affects ATT and SN, while ACC is influenced by KCC and sex. Conversely, PBC influenced INT but showed no association with the other input variables. SN was found to have the greatest impact on INT during sports spectating, while the influence of PBC was relatively low. CONCLUSIONS The causal structure inferred in the current study using Bayesian network learning provides insights into the previously underexplored relationship structure explaining eco-friendly behavioral intentions of sports fans in the field of sports science. The findings of this study can serve as empirical evidence for sports-related organizations to develop strategies and decision-making processes to promote sustainable sports spectatorship.
PURPOSE This study aimed to compare body composition, physical fitness, maximum muscle strength, and blood lactate concentration according to the level of aerobic capacity in Keirin cyclists. METHODS Forty-four Keirin cyclists participated in this study and were divided into three groups: the top 20% VO2max group (TG, n=9), the middle 20% VO2max group (MG, n=9), and the low 20% VO2max group (LG, n=9). The study measured body composition, physical fitness, maximum muscle strength, and blood lactate concentration in Keirin cyclists. Differences between groups were determined using one-way ANOVA analysis. RESULTS Body weight, percentage of body fat, and body mass index were significantly higher in the LG than in the TG and MG. The vertical jump and maximum muscle strength were significantly higher in the TG and MG than in the LG. Additionally, blood lactate concentrations immediately after exhaustive exercise and during the 5-minute recovery periods were higher in the LG than in the TG and MG. Moreover, the time to exhaustion, HRmax and maximum power were the highest in the TG. CONCLUSIONS Our findings suggest new information that levels of aerobic capacity in male Keirin cyclists might be a crucial predictor of cycling performance and recovery ability.
PURPOSE This study aimed to verify the criterion validity of the two-minute step test in older Korean adults, develop an equation for predicting VO2max, and verify cross-validation. METHODS A submaximal exercise test and the two-minute walk test were performed on 150 older adults (74 males and 74 females) aged 65 years or older. Correlation analysis was performed to confirm criterion validity. An equation for estimating VO2max was developed through multiple regression analysis, and cross-validation was confirmed by performing a correlation analysis between measured and predicted values of VO2max. RESULTS The correlation coefficient between VO2max and the two-minute step test was 0.457 (p<.001). The adjusted R2 of the developed VO2max prediction equation was 0.430 (p<.001), and the explanatory variables finally selected were sex, age, number of steps in the two-minute step test, and percentage of body fat. The correlation coefficient between the measured VO2max (19.08±4.36) and the predicted VO2max (19.73±3.36) was 0.654 (p<.001). CONCLUSIONS This study confirmed the criterion validity of the two-minute step test in older Korean adults, and the cross-validation of the developed VO2max prediction formula was verified. The explanatory variables of the prediction equation will be easy to apply in the field, and more meaningful results will be derived if the validity of the prediction equation developed for a larger number of participants is verified.
PURPOSE The purpose of this study was to examine the effects of an eye movement exercise intervention on cognitive function and prefrontal cortex connectivity in the elderly with mild cognitive impairment. METHODS Ten older adults with mild cognitive impairment participated in eye movement exercise consisting of saccadic eye movement, pursuit eye movement, vestibular-ocular eye movement, and vergence eye movement for 4 weeks. Cognitive function (MoCA-K), reaction time during stroop task, and prefrontal cortex connectivity were measured using the functional near-infrared spectrometric analyzer (fNIRS) before and after the intervention. RESULTS First, cognitive function of the elderly with mild cognitive impairment showed significant improvement after the eye movement exercise (p < .05). Second, reaction time decreased significantly from 1.16 to 0.91 ms after eye movement exercise. Third, the strength of prefrontal cortex connectivity (left OFC - right FPC, right OFC - right FPC) increased after the intervention in the older adults with mild cognitive impairment. CONCLUSIONS The results of this study suggest that eye movement exercise is an effective intervention for improving cognitive function through improvement of brain functional connection in the elderly patients with mild cognitive impairment.
PURPOSE The purpose of this study was to identify the scoring patterns of male and female Korean judo athletes by weight class, based on major international competitions from 2016 to 2021. METHODS We analyzed 1,508 scoring techniques, consisting of penalty, Waza-ari, and Ippon connected techniques, from male and female Korean athletes who participated in the Grand Prix, Grand Slam, Masters, World Championships, and Olympics. Chi-squared tests were conducted to examine differences in rounds, time, results, techniques, and continent by weight class. RESULTS In terms of differences in rounds, statistically significant differences were found in the men's lightweight and women's heavyweight categories. Statistically significant differences were found in the following: regarding differences in match time, in the men's heavyweight category; regarding match results, in the men's heavyweight category; and regarding differences in technique type, in the men's middleweight and heavyweight categories and in the women's lightweight and heavyweight categories. Finally, in terms of opponent continents, significant differences were found in both men's and women's lightweight categories. CONCLUSIONS In conclusion, this study confirmed the differences in wins and losses of male and female Korean athletes according to their weight classes. Based on this, it is necessary to analyze and systematize the technology types of the world's top athletes, including Korean athletes, to improve their judo performance.
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.
