PURPOSE This study analyzed differences in ball speed and kinematic, kinetic characteristics according to stride length. METHODS Forty participants recruited for the study were divided into two groups based on stride length: an over stride group (overstride, OS) and an under stride group (understride, US). Independent sample t-tests were conducted to analyze differences in pelvis and trunk kinematics, ground reaction forces (GRF), and timing of pitch between groups. RESULTS Significant differences were found between groups in drive leg GRF impulse, pelvis, trunk closed angle and pelvic angular velocity (p<.05). Furthermore, the OS had statistically later pitching timings than the US at stride foot contact, maximal external rotation, and ball release phases (p<.05). CONCLUSIONS The maximized drive leg GRF impulse created a wider stride, significantly increasing the pelvis and trunk’s opening angles. Additionally, the OS displayed characteristics of later pitching timings compared to the US. However, since no significant differences in ball speed were observed between groups based on stride length, perhaps stride length does not contribute directly to ball speed. Future research should investigate optimal stride length tailored to individual flexibility and physical characteristics.
PURPOSE This study compared the spatiotemporal gait parameters and kinetic variables of lower extremity joints during gait between normal and presarcopenia groups of middle-aged women. METHODS Middle-aged women participants (n=24) were divided into two groups based on the Appendicular Lean Mass Index (ALMI): a normal group (n=12) and a presarcopenia group (n=12). During walking by each group, spatio-temporal gait variables and the maximum moments and net joint power of the ankle, knee, and hip joints in different directions were calculated and compared using independent samples t-tests with IBM SPSS 27.0 software. RESULTS The normal group and the presarcopenia group showed no statistically significant differences in spatiotemporal gait variables. However, during the shock absorption phase of gait, the presarcopenia group showed significantly higher maximum knee abduction, maximum knee internal rotation, and maximum hip external rotation moments than the normal group. Additionally, the presarcopenia group exhibited significantly higher maximum net knee power during the shock absorption phase. Conversely, during the propulsion phase of gait, the normal group exhibited significantly higher maximum net ankle power than the presarcopenia group. CONCLUSIONS Middle-aged women with presarcopenia experienced higher knee joint loading and lower ankle joint propulsion during walking, indicating the need for training to improve lower limb strength.
PURPOSE This study investigated the correlation between anaerobic power and maximum muscle strength in relation to core muscle strength among Korean national golfers. METHODS A total of 96 national golfers (53 females and 43 males) participated in the study. Body composition was assessed using multi-frequency impedance devices, while core and lower extremity muscle strength (extension, flexion, flex/ex ratio) was measured using isokinetic strength tests. Anaerobic power was evaluated through peak power, average power, and power drop rate tests conducted on bicycle ergometers, along with one-repetition maximum (1RM) tests for squats and bench presses. Mean and standard deviation values were calculated for all variables, and linear regression analysis was performed to verify correlations, with statistical significance set at α=.05. RESULTS The comparison of physical characteristics between male and female national golfers revealed significant differences in age, height, body fat percentage, lean body mass, and weight. There was a strong correlation between core muscle strength and isokinetic lower extremity muscle strength. Additionally, a strong correlation was observed between core muscle strength and anaerobic power and between peak power and average power. Furthermore, there was a high correlation between core muscle strength and bench press and squat maximum muscle strength. CONCLUSIONS This study highlights the correlation between various professional physical fitness variables of Korean national golfers over the past decade. The findings are expected to provide valuable insights for coaches and players in developing future training programs.
PURPOSE This study aimed to investigate the occurrence of sports injuries among badminton national team candidates during training camps and to identify appropriate measures for players to effectively manage and respond to such injuries in the future. METHODS The participants consisted of 123 individuals who took part in national team candidate training camps for badminton in 2022 and 2023. Record sheets were utilized to document the athletes' thoughts and opinions related to exercise injuries during the training period. RESULTS Badminton national team candidates experienced exercise-related injuries in various areas, including the ankles, thighs, knees, hips, shoulders, and back. Female players had a higher incidence of lower body injuries compared to their male counterparts. Through interviews with players about these injuries, individualized approaches involving appropriate rest and training adjustments were found to be necessary; additionally, educating the players about rehabilitation strategies for exercise injuries is essential. CONCLUSIONS When conducting recreational training activities, it is important to avoid fostering excessive competitive attitudes. Additionally, if potential risks are present within the exercise environment, it is crucial to assess and address these with the utmost caution.
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.
