달리기 시 일정한 속도에서 보폭 차이가 하지 관절의 3차원 힘과 모멘트에 미치는 영향

류지선 한국운동역학회 2002 한국운동역학회지 Vol.12 No.1

The Development of Rhythmic Balance Training Equipment and its Effect on Performance for Elderly

( Da Won Park ),( Cho Rong Won ),( Sung Ro Lee ),( Yang Sun Park ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: The aims of this study were 1) to develop easy-to-use rhythmic balance training equipment for the elderly and 2) to investigate the effect of training with the equipment on balance and physical function. Method: Twenty-one elderly individuals (age: 75.4±3.34 yrs, height: 152.07±4.81 cm, weight: 58.35±8.34 kg) participated in this study. Each participant underwent balance and physical function testing before and after 12 weeks of training with the equipment. Y-balance (i.e. dynamic balance) and one leg static balance tests were used for balance testing, and timed up- and-down-stairs and five times sit-to-stand tests were used for physical function testing. A paired t test was used to determine whether there was a significant pre- and post-training difference. Results: The rhythmic balance training equipment provided a fun and motivating training program with age-friendly music, dance movements for lower extremity strength training, and touch screen controls with simple features. Post-training left foot dynamic balance was significantly greater (p<.05), and static balance with eyes open was significantly improved (p<.05) compared to pre-training. Completion of the timed upand- down-stairs and the five times sit-to-stand tests was significantly shorter (p<.05) compared to pre training. Conclusion: Training using the equipment developed in this study improved balance and physical function in elderly participants.

Kinematical Analysis of Somersault with Twist in Men`s Vault: Focusing on the Lou Yun and Akopian Motions

( Kyu Chan Lim ),( Hyung Suh Park ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: The aim of this study was to determine the kinematical characteristics of somersault with twist in the Lou Yun and Akopian motions and to provide useful information to gymnastic athletes in men``s vault. Method: The study subjects were 12 male adult top athletes. After 12 trials (7 Lou Yun and 5 Akopian trials) filmed by using two digital high-speed camcorders set at 90 frames/sec, kinematical data were collected through the direct linear transformation (DLT) method. The mean differences in biomechanical variables were compared during the second flight upward phase. The kinematic characteristics of somersault with twist in the Lou Yun and Akopian motions were identified. Results: In Lou Yun motion, the vertical release velocity through horse breaking was not difficult to obtain, so the athletes had enough time to prepare for the twist. Therefore, the Lou Yun motion has an advantage to make a cat twist in the pike posture. In the Akopian motion, obtaining the horizontal velocity through horse pushing was so easy that the Akopian athletes attained a large angular impulse and angular momentum. Therefore, the Akopian motion has an advantage to making a tilt twist in the body tilting posture. Conclusion: This study suggests that gymnastic athletes should control their body segment movements in order to increase the twisting angular velocity of the whole body, which requires regulation of the longitudinal moment of inertia of the body. Moreover, athletes should prepare for the shoulder and hip twists early in order to make the landing position in advance.

Relationship between Dimensionless Leg Stiffness and Kinetic Variables during Gait Performance, and its Modulation with Body Weight

( Seung Hyun Hyun ),( Che Cheong Ryew ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: This purpose of this study was to analyze the relationship between dimensionless leg stiffness and kinetic variables during gait performance, and its modulation with body weight. Method: The study sample consisted of 10 young women divided into 2 groups (Control, n=5 and Obese, n=5). Four camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) and one force plate (AMTI., USA) were used to analyze the vertical ground reaction force (GRF) variables, center of pressure (COP), low limb joint angle, position of pelvis center and leg lengths during the stance phase of the gait cycle. Results: Our results revealed that the center of mass (COM) displacement velocity along the y axis was significantly higher in the obese group than that in control subjects. Displacement in the position of the center of the pelvis center (Z-axis) was also significantly higher in the obese group than that in control subjects. In addition, the peak vertical force (PVF) and dimensionless leg stiffness were also significantly higher in the obese group. However, when normalized to the body weight, the PVF did not show a significant betweengroup difference. When normalized to the leg length, the PVF and stiffness were both lower in the obese group than in control subjects. Conclusion: In the context of performance, we concluded that increased dimensionless leg stiffness during the gait cycle is associated with increased velocity of COM, PVF, and the change in leg lengths (%).

Effects of Prolonged Running-Induced Fatigue on the Periodicity of Shank-Foot Segment Coupling and Free Torque

( Ji Seon Ryu ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: The purpose of this study was to determine the periodicity of shank-foot segment coupling and free torque before and after fatigue induced by prolonged running. Method: Fifteen young healthy male participants with a rear-foot strike ran on instrumented dual belt treadmills at 70% of their maximum oxygen uptake for 65 min. Kinematic and ground reaction force data were collected for 20 continuous strides at 5 and 65 min (considered the fatigued condition). The approximate entropy tool was applied to assess the periodicity of the shank internal-external rotation, foot inversioneversion, shank-foot segment coupling, and free torque for the two running conditions. Results: The periodicity of all studied parameters, except foot inversion-eversion, decreased after 65 min of running (fatigued condition) for 80% of the participants in this study. Furthermore, 60% of the participants showed similarities in the change of periodicity pattern in shank internal-external rotation, coupling, and free torque. Conclusion: The findings indicated that the foot inversion-eversion motion may pose a higher risk of injury than the shank internal-external rotation, coupling, and free torque in the fatigued condition during prolonged running.

An Analysis of X-Factor, Triple X-Factor, and the Center of Pressure (COP) according to the Feel of the Golf Driver Swing

( Yong Seok Kim ),( Jae Moo So ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: The aim of this study was to analyze X-factor, triple X-factor, and the center of pressure (COP) according to the feel of golf driver swing. Method: For this research, 9 golfers from the Korea Professional Golfers`` Association (age: 30.11±2.98 yrs, height: 178.00±8.42 cm, weight: 76.22±8.42 kg, experience: 10.06±3.11 yrs) were recruited to participate in the experiment. Twelve Motion Analysis Eagle-4 cameras were installed and an image analysis was conducted by using the NLT (non-linear transformation) method, and 2 units of Kistler type 5233A dynamometer were used to measure ground reaction force. The sampling ratio was set at 1000 Hz. The golfers each took 10 swings by using their own driver, and chose the best and worse feel from among 10 shots. A paired-sample t-test was used to analyze the results. Results: In regard to feel, no change in head speed, X-factor, and the triple X-factor``s X factor stretch, hip rise, and head swivel, was observed (p>.05). Regarding ground reaction force, a difference was observed between the top of the backswing (p<.05) and impact (p<.05) in the vertical force of the left foot. For COP, a difference was also observed between the mid backswing (p<.001), late backswing (p<.001), and top of the backswing (p<.05) for the right foot X-axis and Y-axis mid follow through (p<.01). Conclusion: It can be reasoned that, irrespective of feel, the head speed, X-factor and triple X factor``s Xfactor stretch, hip rise and head swivel did not have an effect on drive distance for domestic golfers, and the vertical reaction force of the left foot and left-right movement span``s pressure dispersal of the right foot had an increasing effect on drive distance.

The Effects of Upper Limb, Trunk, and Pelvis Movements on Apkubi Momtong Baro Jireugi Velocity in Taekwondo

( Si Hyun Yoo ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: The purpose of this study was to investigate effects of upper limb, trunk, and pelvis kinematic variables on the velocity of Apkubi Momtong Baro Jireugi in Taekwondo. Method: Twenty Taekwondo Poomsae athletes (age: 20.8±2.2 years, height: 171.5±7.0 cm, body weight: 66.2 ±8.0 kg) participated in this study. The variables were upper limb velocity and acceleration; trunk angle, angular velocity, and angular acceleration; pelvis angle, angular velocity, and angular acceleration; and waist angle, angular velocity, and angular acceleration. Pearson``s correlation coefficient was calculated for Jireugi velocity and kinematic variables; multiple regression analysis was performed to investigate influence on Jireugi velocity. Results: Angular trunk acceleration and linear upper arm punching acceleration had significant effects on Jireugi velocity (p<.05). Conclusion: We affirmed that angular trunk acceleration and linear upper arm punching acceleration increase the Jireugi velocity.

The Effects of the Upright Body Type Exercise Program on Foot Plantar Pressure of Archers

( Dong Kuk Kim ),( Joong Sook Lee ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: This study collected data on muscle fatigue and ground reaction force during walking to provide a basis for development of custom-fitted outdoor walking shoes. The study analyzed an upright body exercise program using spine stabilization technique to determine the effect on foot plantar pressure in archers, demonstrate the effectiveness of upright body exercise, and develop a new, effective, and efficient training program. Method: A 12-week upright body exercise program was evaluated for the effect on plantar pressure in archers. Ten prize-winning archers (3 men, 7 women) in B metropolitan city, each with ≥10 years of experience, were given an explanation of the content and purpose of the program, and provided informed consent. Upright body exercise was performed 3 times a week for 12 weeks. A resistive pressure sensor was used to measure foot plantar pressure distribution and analyze quantitative information on variation in postural stability and weight shifting in dynamic balance during shooting, as well as plantar pressure in static balance with the eyes open and closed. Results: There were no significant differences in foot plantar pressure before and after participation in the exercise program. There was no statistically significant difference in foot plantar pressure in static balance with the eyes open or closed, or in foot plantar pressure in dynamic balance during shooting. Conclusion: An upright body exercise program had positive effects on foot plantar pressure in static and dynamic balance in archers by reducing body sway and physical imbalance during shooting and with eyes closed. This program is expected to help archers improve their posture and psychological state, and thereby improve performance.

Effects of Freezing of Gait and Visual Information on the Static Postural Control Ability in Patients with Parkinson`s Disease

( Jung Yee Kim ),( Min Ji Son ),( You Kyung Kim ),( Meoung Gon Lee ),( Jin Hee Kim ),( Chang Hong Youm ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.3

Objective: The purpose of this study was to analyze the effects of freezing of gait and visual information on the static postural control ability in patients with Parkinson``s Disease (PD) during the bipedal stance with feet together. Method: This study included a total of 36 patients with PD; the freezer group included 17 PD patients (age: 69.3±6.2 yrs, height: 159.6±9.0 cm, weight: 63.4±9.78 kg) and the nonfreezer group included 19 PD patients (age: 71.4±5.6 yrs, height: 155.8±7.1 cm, weight: 57.7±8.6 kg). Static postural control ability was analyzed using variables of center of pressure (COP) and dividing by mediolateral, anteroposterior, and integration factors during a bipedal stance with the eyes open and closed. Results: Freezers and nonfreezers showed increases in anteroposterior velocity, mediolateral velocity, averaged velocity, and mediolateral 95% edge frequency when visual information was blocked. Additionally, freezers had greater anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position than nonfreezers. Conclusion: Freezers and nonfreezers showed a reduction in static postural control ability when visual information was blocked. Additionally, the results of this study found a significant difference in static postural control ability between freezers and nonfreezers with PD. In particular, anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position might be used to distinguish between freezers and nonfreezers with PD.

Analysis of Lower Extremity Joint Moment and Power during Squat in Female Patients with Genu Varum

( Ji-man Jeong ),( Bee-oh Lim ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.4

Objective: The aim of this study was to analyze the net joint moment and joint power of the lower extremity during squat in female patients with genu varum. Method: Eight female patients with genu varum were asked to do regular squats, and their net joint moment and joint power were compared to those of another eight female participants with straight legs. Their video recordings and ground reaction force data were analyzed to be used as a theoretical evidence of squatting effectively for female patients with genu varum. Results: Squats had a higher impact on internal knee joint rotation and ankle joint flexion moments in the genu varum group than in the straight leg group due to their weak and short hip joint muscles. Conclusion: There is a need to develop a squat movement that is appropriate for women with genu varum in order to distribute overload efficiently among the hip, knee, and ankle joints and to strengthen the muscles in a balanced way.