• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.83-94
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• 2012

The purpose of this study was to analyse the effect of posture correction & stabilization according to horse rider's(n=10) skill levels of novice(0wk), mid-skill(12wk) & skill(24wk) in walk & trot. First, Mean posture of 3 times experiments; Anterior & posterior leaning posture of trunk showed rather unstable according to progress of the stages of TD1, TO, TD2 phase, and also shoulder & elbow angle, which effects to the distance from bit to rein, showed unstable riding posture. There was close relationship between shoulder and elbow Angle in walk and hip, knee & ankle angle in trot. Second, Posture correction & stabilization according to riding skill levels; Anterior & posterior leaning posture of trunk did not show significant difference statistically but showed approaching tendency to trunk's vertical line and showed significant difference(p<.05) according to improvement of skill levels in walk & trot horse riding. Hip angle showed significant difference according to progress of the stages of TD1, TO, TD2 phase(p<.05) and showed tendency maintaining the larger thigh flexion according to improvement of skill levels in walk & trot. Knee angle showed more stable posture by maintaining the larger flexion between thigh and shank according to improvement of skill levels in walk & trot(p<.05). Ankle angle also showed tendency maintaining the larger plantar flexion of foot according to improvement of skill levels in walk & trot. When considering the above, regular horse riding program could be useful in posture correction & stabilization according to improvement of skill levels of novice(0wk), mid-skill(12wk) & skill(24wk) in walk & trot.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.111-119
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• 2007

The purpose of this study was to investigate muscle activity and gait pattern in lower limb depending on the outsole of heel rockers. Fifteen healthy men volunteered for this experiment. Each subject performed totally three trails with two pairs of different heel rocker shoes and a pair of normal running shoes at speed of 1.33m/s for 1 minute during walking on a treadmill. Kinematic data gathered in 100Hz was recorded and analyzed by using the 3D motion capture system to measure the trunk tilt and joint angle of the right lower limb. And the lower extremity muscle activities were simultaneously recorded in 1000Hz and assessed by using EMG. The statistical analysis was the one-way ANOVA with the repeated measures to compare among the three kinds of shoes. The level of statistical significance for all tests was 0.05. Joint angle of lower limb was showed statistically significant different in MST(hip joint), LHS(ankle joint), and RTO(knee and ankle joint). Muscle activity of rectus femoris and biceps femoris was statistically increased in both heel rocker shoes during gait cycle on treadmill. The maximum peak time of tibialis anterior in the negative heel rocker showed the delay of approximately 23.8%time than normal shoes. Gait pattern variability of the negative heel rocker was increased in the first half of the stance phase and the variability of the positive heel rocker was increased in the terminal stance phase. In Conclusion, stability was decreased in between joints of lower limb on positive heel rocker than negative heel rocker. This study found that there were different joint angle, muscle activity, gait pattern and coordinate system of the lower limb in each kind of shoes. These unstability affected the lower extremity and the whole body. A further study has to be continued with study of rehabilitation and exercise for a long-term.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.433-441
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• 2016

Objective: The purpose of this study was to understand the injury mechanism and to provide quantitative data to use in prevention or posture correction training by conducting kinematic and kinetic analyses of risk factors of lower extremity joint injury depending on the change of direction at different angles after a landing motion. Method: This study included 11 men in their twenties (age: $24.6{\pm}1.7years$, height: $176.6{\pm}4.4cm$, weight: $71.3{\pm}8.0kg$) who were right-leg dominant. By using seven infrared cameras (Oqus 300, Qualisys, Sweden), one force platform (AMTI, USA), and an accelerometer (Noraxon, USA), single-leg drop landing was performed at a height of 30 cm. The joint range of motion (ROM) of the lower extremity, peak joint moment, peak joint power, peak vertical ground reaction force (GRF), and peak vertical acceleration were measured. For statistical analysis, one-way repeated-measures analysis of variance was conducted at a significance level of ${\alpha}$ <.05. Results: Ankle and knee joint ROM in the sagittal plane significantly differed, respectively (F = 3.145, p = .024; F = 14.183, p = .000), depending on the change of direction. However, no significant differences were observed in the ROM of ankle and knee joint in the transverse plane. Significant differences in peak joint moment were also observed but no statistically significant differences were found in negative joint power between the conditions. Peak vertical GRF was high in landing (LAD) and after landing, left $45^{\circ}$ cutting (LLC), with a significant difference (F = 9.363, p = .000). The peak vertical acceleration was relatively high in LAD and LLC compared with other conditions, but the difference was not significant. Conclusion: We conclude that moving in the left direction may expose athletes to greater injury risk in terms of joint kinetics than moving in the right direction. However, further investigation of joint injury mechanisms in sports would be required to confirm these findings.

• Korean Journal of Applied Biomechanics
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• v.29 no.2
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• pp.79-88
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• 2019

Objective: The aim of this study was to determine the peak torques of the knee and ankle joint and local stability of the lower extremity's joints, and muscle activation patterns of the lower extremity's muscles between fallers and non-fallers in the elderly women during walking. Method: Four elderly women (age: $74.5{\pm}5.2yrs.$; height: $152.1{\pm}5.6cm$; mass: $55.3{\pm}5.4kg$; preference walking speed: $1.19{\pm}0.06m/s$) who experienced falls within six months since experiment had been conducted (falls group) and thirty-six subjects ($74.2{\pm}3.09yrs.$; height: $153.6{\pm}4.9cm$; mass: $56.7{\pm}6.4kg$; preference walking speed: $1.24{\pm}0.10m/s$) who had no experience in falls (non-falls group) within this periods participated in this study. They were measured torque peaks of the knee and ankle joint using a Human Norm and while they were walking on a treadmill at their natural pace, kinematic variables and EMG signals were collected with using a 3-D motion capture system and a wireless EMG system, respectively. Lyapunov Exponent (LyE) was determined to observe the dynamic local stability of the lower extremity's joints, and muscles activation and their co-contraction index were also analysed from EMG signals. Hypotheses between falls and non-falls group were tested using paired t-test and Mann-Whitey. Level of significance was set at p<.05. Results: Local dynamic stability in the adduction-abduction movement of the knee joint was significantly lower in falling group than non-falling group (p<.05). Conclusion: In conclusion, muscles which act on the abduction-adduction movement of the knee joint need to be strengthened to prevent from potential falls during walking. However, a small number of samples for fallers make it difficult to generalize the results of this study.

• International journal of advanced smart convergence
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• v.9 no.4
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• pp.26-33
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• 2020

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.364-375
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• 2009

The purpose of this study is to offer basic data for the fall prevention by analyzing the kinematic difference between the lower limb joints and the lower extremities in elderly people's walking given the lower-limb resistance exercises. For this, three-dimensional image analysis was carried out by selecting 7 elderly women from over 70s to under 80 years old. To obtain the three-dimensional location coordinates in the lower limb joints and the lower extremities, it shot with 100Hz/s by using MCU(Qualisys, Sweden) camera. The shot image gained raw data on the location coordinates by using QTM(Qualisys, Sweden). As a result of calculating three-dimensional angle by using program of Matlab 6.5, the following conclusions were obtained. Flexion and extension in the thigh and the lower-leg extremities were indicated to be big in motion of flexion after exercising at E5. Foot segment indicated statistical difference while showing eversion at E4. Knee joints showed flexion at E4 after exercising. Ankle joints showed statistical difference while indicating motion in inversion at E3 and in eversion at E4(p<.05).

• Korean Journal of Applied Biomechanics
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• v.20 no.1
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• pp.33-39
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• 2010

The purpose of this study was to investigate the changes in walking pattern of the elderly during inclined walkway with uneven surfaces and level walking. 10 young($26.3{\pm}1.3$ years, $174.3{\pm}5.3\;cm$, $69.5{\pm}9.5\;kg$) and 13 elderly($72.4{\pm}5.2$ years, $164.5{\pm}5.4\;cm$, $66.1{\pm}9.6\;kg$) male subjects were participated in the experiment. Experiment consisted of 2 walking conditions: horizontal and inclined walkway with uneven surfaces. 3D motion capturing system were used to acquire and analyze walking motion data with sampling frequency of 120 Hz. To compare differences between conditions, kinematic variables(walking speed, stance-swing ratio, hip joint angle, knee joint angle, ankle joint angle, pelvic rotation angle) were used. Results showed that there were some changes of elderly walking pattern in inclined walkway with uneven surfaces: hip joint(adduction and rotation) and pelvic movement pattern. These changes by inclination and surface may affect gait pattern of young subjects as well as elderly subjects. However, in case of elderly it revealed more unstable gait than the young. Further study is necessary to clarify changes in walking pattern for elderly by considering various gait variables including head movement and various walkway conditions.

• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.51-61
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• 2020

Objective: The purpose of this study is to analyse and comparison the differences of kinematic variables for Fente skill in Fencing. Method: For this, 15 people were selected as 5 beginners with less than 2 years of experience, 5 intermediate-class people with more than 2 years and less than 4 years, and 5 experts-class people with more than 4 years. Through the comparison of Marche Fente motion according to proficiency, for the necessary time, travel distance, the kinematical factor of joint angle, oneway ANOVA was performed in order to identify differences according to variables by phase. Results: The time required for each phase was shown to be shorter for all phases experts than for beginners and intermediates. At the horizontal displacement of the foot, the right foot left out the last phase and the experts appeared long. The left foot showed short beginners in all phases. The angle of forward lean showed that the angle of forward lean was tilted forward by the experts of all phases. There was a difference between the left and right joint angles of the lower limb, both of the ankle, knee and hip joints. Conclusion: In overall, Beginners should quickly widen the distance of their feet when they make a Fente movement. The beginner shall tilt the upper body forward in order to increase the angle of forward lean. The beginner shall, in the last phase, have a smaller angle on the hip joint.

• Journal of the Korea Safety Management & Science
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• v.11 no.2
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• pp.103-110
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• 2009

The purpose of this study is to suggest a proper tread of stairs using kinematic factors and moments of the lower-limb joints in the stair decent with the 3 different treads with boimechanical method in ergonomics. 9 subjects (body masses; $59.41{\pm}7.49$, $64.03{\pm}6.65$, $67.26:{\pm}7.58$, heights; $160.50{\pm}6.35$ ages; $31.22{\pm}2.99$; parity; $1.67{\pm}0.71$) participated in three experiments that were divided by physiological symptoms (the early (0-15 weeks), middle (16-27 weeks) and last (18-39 weeks). and they walked at self-selected pace on 4 staircases 3 trials. As extending the pregnancy period, cadence was shorter but cycle time were longer more and more. As extending treads of stair decent during pregnancy, speed, stride lengths and cycle time were increased. As extending the treads of stair decent, hip and ankle moments increased but knee moments decreased in sagittal plane. There were increasing or decreasing of moments by means of treads. These changes may account for relation between the treads of stair and moments in pregnant women. The main changes of pregnant women were joint moments and kinematic factors during pregnancy period because pregnancy makes them physical changes. It is possible that joints have connection with compensation each other to maximize stability and to control gait motion. In conclusion, we suggest that the tread of stair is longer than 26cm tread. and exercise programs to improve muscle activity were necessary where joint moments were small.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.153-163
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• 2006

The purpose of this research was to analyze kinematic variables that appear during the instep shooting motion of female high school soccer players according to the angle of approach to find effective shooting motions. For this experiment, 5 female high school soccer players from the K city were participated in this study as the subject group, and as a through comparison and analysis of the resulting numbers of the variables, we came to the following conclusions. 1) Stride length and stride length/lower extremity length increased as the angle of approach increased. 2) As for C.O.G movement displacement, it was highest at an approach angle of $90^{\circ}$ during Right Foot Contact, at $135^{\circ}$ during Left Foot Contact, at $0^{\circ}$ during Rigth Toe Top, at $45^{\circ}$ during Impact, and at $0^{\circ}$ during Follow through. 3) The time required for each phase was longest at APP and shortest at BSP. The time required increased a little as the angle of approach increased, and the total time required also increased as the angle of approach increased. 4) The angle of the ankle joint was largest at an approach angle of $45^{\circ}$ for all events except Right Foot Contact. 5) The angle of the knee joint was largest at an approach angle of $135^{\circ}$ during Right Foot Contact, at $0^{\circ}$ during Left Foot Contact, at $45^{\circ}$ during Right Toe Top, at $135^{\circ}$ during Impact, and at $90^{\circ}$ during Follow through. 6) The angle of the hip joint was largest at an approach angle of $90^{\circ}$ during Right Foot Contact, at$0^{\circ}$ during Left Foot Contact, at $0^{\circ}$ during Right Toe Top, at $90^{\circ}$ during Impact, and at $0^{\circ}$ during Follow through.