The purpose of this research is to investigate the factors affecting the performance capability of lunge movements by performing lunge movements which are commonly used as a method of instant physical movement in sports with a kinetic analysis including an EMG analysis. This research targeted 14 skilled fencers and made the subjects perform kick-lunges which allow them to go farthest from their positions and performed an analysis on such, applying a 3D motion analysis system and an EMG system. The subjects performed kick-lunges in two movements; one with a preliminary movement and the other without it and those are performed with both dominant leg and non-dominant leg. The result of this research is as follows. The lunges with a preliminary movement showed higher performance capability than those without it. Furthermore, as the level of skills gets higher, the length of lunges gets longer, and it seemed that a tactical mechanism shortening exercise performance times was used as a mechanism to control the impulse coming from such lengthened lunges. In addition, a difference appeared in mechanical factors such as moment and power in a dominant leg movement and it seemed to result from a difference in an functional capability using muscles.
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 aimed to investigate the effect of an ankle strap on kinetic variables of the lower limb during forward jump landing. METHODS Twelve healthy adult men (mean age, 23.58±2.22 years; mean height, 177.83±5.37 cm; mean weight, 75.00±7.72 kg) participated. The participants stood barefoot on both legs at a horizontal distance of 40% of their body height from the center of the force plate, then jumped forward and landed on the force plate with their dominant or non-dominant leg over a 30-cm hurdle while wearing or not wearing an ankle strap. Joint angle, peak vertical force, loading rate, and leg stiffness were calculated. Paired t-test and repeated-measures two-way analysis of variance with Bonferroni’s post hoc tests were used to compare the characteristics of both lower limbs and the effect of wearing an ankle strap. The significance level was α < .05 RESULTS Our results showed significant differences in kinematic variables between the dominant and non-dominant legs without the ankle strap. With the ankle strap, the inversion angles at the ankle joints of both lower extremities were significantly decreased, and an interaction effect between both legs and the ankle strap occurred in the internal rotation angle of the ankle joint. Kinetic variables did not differ significantly. CONCLUSIONS The ankle strap did not completely compensate for ankle instability in the non-dominant leg, but it significantly reduced the angle of internal rotation at the ankle joint. Thus, we recommend that correct wearing of the ankle strap in sports since it reduces the possibility of lateral ankle sprains to some extent.
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.
The human foot is only part that directly contact between the body and the external environment, and is ideally positioned to provide sensory information to the Central Nervous System (CNS) during static and dynamic tasks. Through cutaneous mechanoreceptors located in the dermis, the foot is able to recognize touch pressure and vibration stimuli, which provide important feedback information used for the fine coordination of movements. The purpose of this study is to quantitatively examine the effect of changing the foot cutaneous sensory by temperature stimulus on maximal performance and muscle activation using wavelet technique. Sixteen healthy subjects volunteered to participate in this study (Male: Age 21.4±2.4years; Height 174.7±5.3츠; Weight 70.6±5.2kg; Female: Age 20.5±0.6years; Height 163.2±3.1cm; Weight 55.6±4.8kg). Sensory pressure thresholds were determined for the plantar surface of the foot using monofilament. Kinematic, kinetic and EMG data which relative to maximal performance were collected while squat jumping in each temperature condition(cool 12-15℃ normal 28-30℃ hot 45-48℃). Maximal jump height was significant higher in normal condition. Vertical GRF in normal condition showed higher peak value the other conditions. And then EMG signal were significant different between temperature conditions during maximal performance. By changed sensory feedback on temperature, one can alter maximal performance and muscle activation pattern. Cutaneous feedback is important in performance and neuromuscular control, and temperature changes significantly influence on lower extremity during maximal squat jump performance of healthy subjects.
PURPOSE The purpose of this study was to provide information for improving the performance and skills of 500 m speed skaters by analyzing the kinematic and kinetic changes in their slide board movements over time. METHODS The subjects were 10 male short-distance skaters in their 20s to 30s who were registered as professional athletes with the Korea Sports Council. The changes in joint angle, joint moment, and joint power over time in the subjects’ slide board motion were measured and analyzed. RESULTS It was found that during phase 2 of the skater’s slide board movement, there was an increase in plantar flexion and a decrease in flexion of the lower extremity joint and extension of the knee and hip joint, with decrease in positive power of the knee joint. CONCLUSIONS The results of this study are expected to provide practical information to skating coaches and athletes by quantifying the biomechanical factors observed over time during slide board movements. In addition, this study is expected to contribute to the field of speed skating by presenting scientific training methods and proposing new analysis techniques to improve performance in the future.
