• Physical Therapy Korea
• /
• 제18권2호
• /
• pp.60-66
• /
• 2011

Foot posture is important in the development of the musculoskeletal structure in the lower limbs because it can change the mechanical alignment. Although foot orthotics are widely used for the correction of malalignments in the lower extremities, the biomechanical effects of wedges have not yet been cleared. The aim of this study was to investigate whether medial wedges affect the electromyographic (EMG) activity of the knee and hip joints in healthy adults that are performing one leg standing. Seventeen healthy volunteers performed the one leg standing under two foot conditions: A level surface, and a $15^{\circ}$ medial wedge. The subjects' EMG data for the gluteus maximus (Gmax), gluteus medius (Gmed), tensor fasciae latae (TFL), biceps femoris (BF), vastus lateralis (VL), and vastus medialis oblique (VMO) were recorded, along with the surface EMG, and all were analyzed. The EMG activity of the Gmed and TFL had significantly decreased under the medial wedge condition during one leg standing. Further study is needed in order to investigate whether medial wedges influence the EMG activity and kinematic data of the knee and hip joints as well as the ankle joints in adults with flexible flatfoot, while they are performing one leg standing.

• Korean Journal of Applied Biomechanics
• /
• 제13권3호
• /
• pp.163-180
• /
• 2003

This paper aims at collecting the guantitative data of kenematic variables by analysing the gait patterns of the normal adult men and the handicapped. The gait motions were taped with 4 video cameras, the cinematographic analyses were performed by the DLT technique of three dimensional image treatment. The following results were obtained in the analysis of the variables: 1. The ratio of stance time and swing time did not show any significant difference in the groups of the normal men and the handicapped when both foot of the former and the right feet of the latter were compared. The stride peeriod time of these two groups were 1.12 and 1.11 second, respectively. 2. In the handicapped group, the step width was wider, the step length and stride length were shorter, and especially, the step length of the right foot was shorter, 3. The small vertical displacement of left toes of the handicapped group showed that the heal contact and the left midstance are almost simultaneous. 4. The two groups have almost the same horizontal displacement of the center of gravity and the same vertical rate of extension. In view of the velocity of the center of gravity the normal adults showed the constant speed of movement. However, the handicapped adults were reduced from the right midstance to the right toe-off. 5. The handicapped showed prominently low angle on the left toe-off in the ankle joint angle, they also had the tendency to walk in the patterns of extended knee in the knee joint angle. Both the handicapped and the normal had the hyperextension on the toe-off in the hip joint angle. In the back and front angle of body, both showed the slightly back-sided walking positions. 6. Both groups had the abduction of both feet in foot placement angle, but the handicapped did not show serious abduction of left midstance.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• 제38권1호
• /
• pp.57-62
• /
• 2014

Most analytical models of the human body have focused on conscious responses. A patellar tendon reflex, a representative example of spinal reflexes, occurs without a neural command. Muscle forces and activation of the quadriceps femoris muscles in healthy adults during patellar tendon reflex are identified in this study. The model is assumed to move in the sagittal plane, and the thigh and the trunk are assumed to be fixed in a sitting position so that the shank can move similar to a pendulum. The knee joint is modeled as a revolute joint, and the ankle joint is modeled as a fixed joint so that the shank and the foot can be regarded as one rigid body. Muscle forces are calculated following the inverse dynamic approach. Kinematic data obtained from an experiment (Mamizuka, 2007) are used as input data. Muscle activations are identified using a Hill-type muscle model. The obtained simulation results are compared with experimental results for validating the model and the underlying assumptions.

• Journal of Korean Physical Therapy Science
• /
• 제8권2호
• /
• pp.961-965
• /
• 2001

The aim of this study is to present the basic reference data of age and specipic gait parameters for Korean Adult. The basic gait parameters were extracted from 20 Adult, 10 men and 10 women, 21 to 24 years of age using VICON 512 Motion Analyzer. The temporal gait parameters and kinematic parameters of Korean Adult similar to other western reference data. The results were as follows: 1) The mean Cadence of the male to the female were 113.5 steps/min to 117.6 steps/min. 2) The mean Walking Speed of the male to the female were 1.30 m/s, to 1.27 m/s. 3) The mean Stride Length of the male to the female were 1.35 m, to 1.30 m. 4) The mean maximal angles of pint on the pelvic tilt motion for different male to the female were $9.80^{\circ}$ to $7.75^{\circ}$. (p<0.05) 5) The mean maximal angles of pint on the hip flexion motion for different male to the female were $22.62^{\circ}$ to $27.65^{\circ}$. (p<0.05) 6) The mean maximal angles of pint on the knee flexion motion for different male to the female were $55.78^{\circ}$ to $55.49^{\circ}$. (p>0.05) 7) The mean maximal angles of pint on the ankle dorsiflexion motion for different male to the female were $12.47^{\circ}$ to $13.39^{\circ}$. (p>0.05).

• Journal of the Korea Safety Management & Science
• /
• 제12권1호
• /
• pp.51-57
• /
• 2010

Cycling that transform human energy into mechanical energy is one of the man-machine systems out of sports fields. Benchmarking means "improving ourselves by learning from others', therefore benchmarking toward dominant cyclist is necessary on field. The goals of this study were to provide important factors on multi-disciplines (kinematics, physiology, power, psychology) for a tailored-training program that is suitable to individual characteristics. Two cyclists participated in this study and gave consent to the experimental procedure. One was dominant cyclist (years: 21 yrs, height: 177 cm, mass: 70 kg), and the other was non-dominant cyclist (years: 21, height: 176, mass: 70). Kinematic data were recorded using six infrared cameras (240Hz) and QTM (software). Physiological data (VO2max, AT) were acquired according to graded exercising test with cycle ergometer and power with Wingate test used by Bar-Or et. al (1977) and to evaluate muscle function with Cybex. Psychological data were collected with competitive state anxiety inventory (CSAI-2) that was devised by Martens et. al (1990) and athletes' self-management questionnaire (ASMQ) of Huh (2003). It appears that the dominant's CV of ankle joint angle was higher than non-dominant's CV and dominant's pedaling pattern was consistent in biomechanics domain, which the dominant's values for all factors ware higher than non-dominant's values in physical, and physiological domain, and their values between cognitive anxiety and somatic anxiety were contrary to each other in psychology. Further research on multi-disciplines may lead to the development of tailored-optimal training programs applicable with key factors to enhance athletic performance by means of research including athlete, coach and parents.

• Korean Journal of Applied Biomechanics
• /
• 제20권3호
• /
• pp.267-275
• /
• 2010

The purpose of this study was to investigate the effects of balance ability improvement exercise program which applied to the elderly people for increasing balance, stability and range of motion. Ten elderly people and ten university students were recruited as the subjects. Kinematic data were collected by seven real-time infrared cameras while subjects walk stair descent as a pre-test. Korean folk dance exercise program was applied to the elderly for 12 weeks. Same experiment on stair descent walk was performed as post-test. Results indicated that CM movement and selected joint angle patterns of elderly group after treatment changed to the similar patterns of young group. However, ankle joint angle and vertical GRF of elderly group after treatment also increased compared to those of the elderly group before treatment. This might be explained by the fact that elderly used a different walking strategy which maximize support base for increasing stability. Overall, these results indicated that the exercise treatment may affect to adapt and improve the gait pattern of stair descent of elderly people.

• Physical Therapy Korea
• /
• 제9권3호
• /
• pp.77-91
• /
• 2002

Asymmetrical stance posture, balance, and gait disturbance are common problems in hemiplegic patients. Posterior leaf springs (PLS) are frequently prescribed to correct these problems. Recently, anterior leaf springs (ALS) have also been prescribed, but only limited studies have been performed to investigate the effects of ALS. The purpose of this study was to compare the effects of three conditions, i.e., wearing an ALS, wearing a PLS, and not wearing an AFO (ankle foot orthosis),: on 1) the distribution of weight bearing on the affected side, 2) standing balance, and 3) the gait patterns of hemiplegic patients. Eleven hemiplegic patients (10 men and 1 woman) participated in this study. The data were analyzed by the Friedman test. The results were as follows: 1) More weight bearing on the affected leg was observed in the ALS and PLS conditions than in the condition without an AFO. No significant difference between the ALS and PLS conditions was found. 2) There were statistically significant differences in the composite equilibrium scores (CES) among the three conditions. The CES in the PLS condition was significantly higher than in the ALS condition or the condition without an AFO. 3) Gait patterns improved significantly in the ALS and PLS conditions. No statistically significant difference between the ALS and PLS conditions was found. These results suggest that both ALS and PLS effectively improve the distribution of weight bearing on the affected side, standing balance, and gait patterns of hemiplegic patients. Further study using three-dimensional kinematic analysis and dynamic electromyography is needed to support these findings.

• Korean Journal of Applied Biomechanics
• /
• 제19권4호
• /
• pp.627-636
• /
• 2009

This study aims to provide a scientific basis for the abstract beauty of dance by analyzing the effects of controlling the breath during the walking motion of Korean dance. The objective of the study is to determine the significance of breathing during Korean dance, as it is externally expressed and technologically segmented, let alone the internal beauty of Korean dance. The results of this study show that the position of the body center and ASIS during the walking motion that uses breath was lower than that of the walking motion that does not use the breath. In addition, in each replacement of the knee joint and ankle joint, a narrow angle, in which bending is used a lot, appeared during the walking motion that uses the breath, but not during the walking gesture that does not use the breath. This occurred during the bending motion. In the first peak point, the vertical ground reaction force during the walking motion that uses the breath was higher than that during the walking motion that does not use the breath.

• Korean Journal of Applied Biomechanics
• /
• 제16권2호
• /
• pp.25-35
• /
• 2006

The purpose of this study was to investigate the shock attenuation mechanisms while varying the loads in a backpack during drop landing. Ten subjects (age: $22.8{\pm}3.6$, height: $173.5{\pm}4.3$, weight: $70.4{\pm}5.2$) performed drop landing under five varying loads (0, 5kg. 10kg. 20kg. 30kg). By employing two cameras (Sony VX2100) the following kinematic variables (phase time, joint rotational angle and velocity of ankle, knee and hip) were calculated by applying 2D motion analysis. Additional data, i.e. max vertical ground force (VGRF) and acceleration, was acquired by using two AMTI Force plates and a Noraxon Inline Accelerometer Sensor. Through analysing the power spectrum density (PSD), drop landing patterns were classified into four groups and each group was discovered to have a different shock attenuation mechanism. The first pattern that appeared at landing was that the right leg absorbed most of the shock attenuation. The second pattern to appear was that subject quickly transferred the load from the right leg to the left leg as quickly as possible. Thus, this illustrated that two shock attenuation mechanisms occurred during drop landing under varying load conditions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• 제35권11호
• /
• pp.1243-1248
• /
• 2011

The purposes of this study were to develop a dynamic model of a human and to investigate the effect of a walker on an elderly subject's motions, such as sit-to-stand (STS) motion and normal gait, by using this model. A human model consisting of 15 segments and 14 joints was developed, embedded in $RecurDyn^{TM}$, and connected through a Simulink$^{(R)}$ interface with collected motion data. The model was validated by comparisons between joint kinematic results from inverse dynamics (Matlab$^{(R)}$-based in-house program) and from $RecurDyn^{TM}$ simulation during walking. The results indicate that the elderly walker induced a longer movement time in walking, such that the speed of joint flexion/extension was slower than that during a normal gait. The results showed that the muscle activities of parts of the ankle and hamstring were altered by use of the elderly walker. The technique used in this study could be very helpful in applications to biomechanical fields.