• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.133-140
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• 2017

Objective: The purpose of this study was to determine the relationship between center of pressure (CoP) and local stability of the lower joints, which was calculated based on approximate entropy (ApEn) during walking in elderly women. Method: Eighteen elderly women were recruited (age: $66.4{\pm}1.2yrs$; mass: $55.4{\pm}8.3kg$; height: $1.56{\pm}0.04m$) for this study. Before collecting data, reflective marker triads composed of 3 non-collinear spheres were attached to the lateral surface of the thigh and shank near the mid-segment to measure motion of the thigh and shank segments. To measure foot motion, reflective markers were placed on the shoe at the heel, head of the fifth metatarsal, and lateral malleolus, and were also placed on the right anterior-superior iliac spine, left anterior-superior iliac spine, and sacrum to observe pelvic motion. During treadmill walking, kinematic data were recorded using 6 infrared cameras (Oqus 300, Qualisys, Sweden) with a 100 Hz sampling frequency and kinetic data were collected from a treadmill (Instrumented Treadmill, Bertec, USA) for 20 strides. From kinematic data, 3D angles of the lower extremity's joint were calculated using Cardan technique and then ApEn were computed for their angles to evaluate local stability. Range of CoP was determined from the kinetic data. Pearson product-moment and Spearman rank correlation coefficient were applied to find relationship between CoP and ApEn. The level of significance was determined at p<.05. Results: There was a negative linear correlation between CoP and ApEn of hip joint adduction-abduction motion (p<.05), but ApEn of other joint motion did not affect the CoP. Conclusion: It was conjectured that ApEn, local stability index, for adduction/abduction of the hip joint during walking could be useful as a fall predictor.

• Physical Therapy Korea
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• v.26 no.2
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• pp.1-7
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• 2019

Background: In previous studies, changes in postural alignment were found when the slope was changed during walking. Downhill walking straightens the trunk by shifting the line of gravity backward. Objects: This study investigated the effect of the downhill treadmill walking exercise (DTWE) on thoracic angle and thoracic erector spinae (TES) activation in subjects with thoracic kyphosis. Methods: A total of 20 subjects with thoracic kyphosis were recruited for this study. All the subjects performed the DTWE for 30 minutes. A surface EMG and 3D motion capture system were used to measure TES activation and thoracic angle before and after the DTWE. Paired t-tests were used to confirm the effect of the DTWE (p<.05). Results: Both the thoracic angle and TES activation had significantly increased after the DTWE compared to the baseline (p<.05). An increase in the thoracic angle indicates a decrease in kyphosis. Conclusion: The DTWE is effective for thoracic kyphosis patients as it decreases their kyphotic posture and increases the TES activation. Future longitudinal studies are required to investigate the long-term effects of the DTWE.

• Korean Journal of Applied Biomechanics
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• v.28 no.3
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• pp.165-173
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• 2018

Objective: The purpose of this study is to provide biomechanical basis data for the analysis of the maximum vertical ground reaction force, the maximum plantar pressure, the average plantar pressure, and the contact area according to the type of the insole through the insole insertion type foot pressure gauge. Method: In the treadmill, the slope was set at 10%, the first type A was worn at a walking speed of 3.5 km / h, and then walking was carried out using B, C, and D types. Data from 20 boots with consistent walking were extracted and plantar pressure data were collected and analyzed. Results: Functional insole was more effective than conventional insole for maximum vertical ground reaction force, maximum plantar pressure, average plantar pressure, and contact area at 10% of treadmill ramps. Conclusion: In this study, D-type insole supports the cushion in the middle part and supports the heel cup with hardness in the hind part, so that it is the most effective insole by lowering the plantar pressure and dispersing it more widely.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.4
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• pp.440-454
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• 2014

This study examined the wearing effect of 3D compression suits on quantitative electroencephalogram (EEG) during walking and rest. Ten males in their 20s wore three types of experimental clothing, a loose-fit wear (BS), a 3D compression suit (3D CS), and a power film welded on CS (3D WCS); in addition, EEG signals were measured during resting, walking, after walking, and after sit-ups. The results showed that a higher pressure (due to 3D CS and 3D WCS) increased the 'Concentration' level and the 'Cognitive load' of brain waves during treadmill walking due to a higher cortex activity level when walking. Differentiation was shown between two compression suits and BS was enhanced during walking on a treadmill; however, the brain waves of 'Relaxation' between two compression suits were significantly different after walking, i.e., 'Relaxation' level of 3D WCS was the highest. Rigorous exercise such as sit-ups was inefficient to distinguish the effect of compression suits on EEG. Participants perceived a higher pressure due to compression suits; however, the wear comfort of two compression suits was maintained. Two compression suits were rated as supportive and helpful during walking. Various EEG parameters such as the indices of 'Relaxation', 'Concentration' and 'Cognitive load' were effective to observe the effect of 3D compression suits on wearers' brain waves during and after walking.

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.221-228
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• 2016

Objective: The purpose of this study was to investigate differences in gait parameters and symmetry between walking speed by using the Froude number and preferred walking speed. Method: Fifty adults (age: $21.0{\pm}1.7years$, body weight: $71.0{\pm}9.2kg$, height: $1.75{\pm}0.07m$, leg length: $0.89{\pm}0.05m$) participated in this study. Leg length-applied walking speed was calculated by using the Froude number, defined as Fr = ${\upsilon}^2$/gL, where v is the velocity, g is the gravitational acceleration, and L is the leg length. Video data were collected by using eight infrared cameras (Oqus 300, Qualysis, Sweden) and the Qualisys Track Manager software (Qualisys, Sweden), with a 200-Hz sampling frequency during two-speed walking (preferred walking speed [PS] and leg length-applied walking speed [LS]) on a treadmill (Instrumented Treadmill, Bertec, USA). The step length, stride length, support percentage, cadence, lower joint angle, range of motion (ROM), and symmetry index were then calculated by using the Matlab R2009a software. Results: Step and stride lengths were greater in LS than in PS (p < 0.05). The right single-support percentage was greater in LS than in PS (p < 0.05). The hip joint angle at heel contact and toe-off were greater in LS than in PS (p < 0.05). The hip and knee joint ROM were greater in LS than in PS (p < 0.05). Conclusion: Based on our findings, we suggest that increased walking speed had a significant effect on step length, stride length, support percentage, and lower joint ROM.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.1
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• pp.29-34
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• 2011

Purpose : The purpose of this study was to determine the effect of book bag handling styles and types of footwear on muscle activation of erector spine muscles and calf muscles. Methods : Ten participants took off their book bags and used sneakers to walk on a treadmill for 30 minutes. The following day, 10 participants put on their backpack with 10% of the weight and used sneakers to walk on the treadmill for 30 minutes. On the last day, 10 participants put on their backpack with 10% of the weight and used formal shoes to walk on the treadmill for 30 minutes. After walking on the treadmill at 3 mph for thirty minutes, we measured muscle activation in erector spine muscles and calf muscles. Results : The results of this study showed the activation of the erector spine muscles and the calf muscles significantly increased when walking with a book bag and the activation of the erector spine muscles and the calf muscles significantly increased when walking in formal shoes. Conclusion : Using a backpack and formal shoes increase muscle activity of erector spine muscles and calf muscles. The results of this study indicate that not using a backpack and wearing sneakers are more beneficial than that using a backpack weighted 10% and wearing formal shoes and can be recommended to adult women by clinicians.

• PNF and Movement
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• v.18 no.2
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• pp.215-222
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• 2020

Purpose: The study investigated the effect on chronic stroke patients' balance of a weight shift to the affected side using an insole on the less affected side during treadmill walking training. Methods: The subjects were 7 patients who had been diagnosed with stroke 6-24 months prior to the study. In each case, an insole was applied on the patient's less affected side during treadmill walking training. Each training session lasted 30 minutes and was undertaken 5 times per week for 4 weeks. Biorescue equipment that measures shifts in center of pressure was used to assess balance ability as measured by the Korea-Berg balance scale (K-BBS) before and after each training intervention. The Wilcoxon signed-rank test was used to evaluate within-group effects. Results: The results revealed statistically significant before and after differences in area, pressure, length, and mean velocity of the balance test and on K-BBS (p < 0.05). Conclusion: In chronic stroke patients, using an insole to adjust the height of the shoe on the less affected side is an effective means of increasing weight-shifting on the paralyzed side during treadmill gait training.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.155-176
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• 2005

There is some evidence that one of major factors to produce plantar fasciitis depends on the magnitude of the foot arch strain. The orthotics that can reduce the foot arch strain during locomotion may be effective to prevent or treat plantar fasciitis. Therefore, the purpose of this study was to investigate the effect of control condition and three types of foot orthotics on 3-dimensional foot arch strain that can produce plantar fasciitis during treadmill level and uphill walking and running. Sixteen male subjects are recruited and the arch length and height strain according to three types of foot orthotics with respect to control condition were measured by using two digital video cameras. The first hypothesis which the comfort of foot orthotics would be increased from arch pad, half length orthotics to full length orthotics was mostly accepted. It suggested that the types of the foot orthotics could be properly prescribed according foot regions that is pain or abnormal. The second hypothesis which the foot arch strain can be reduced by foot orthotics during level heel-toe walking and running and the third hypothesis which the foot arch strain can be reduced by foot orthotics during uphill heel-toe walking and running were rejected. The foot arch length and height strain during walking and running showed small and subject-specific characteristics and could not be optimal biomechanical variable to prove the overall comfort. The forth hypothesis which the foot arch strain cannot be reduced by foot orthotics during uphill toe walking and running was accepted. With the foot arch length and height strain during uphill toe walking and running the windlass mechanism suggested by Hicks can be explained successfully and excessive uphill toe walking and running can be one of cause of plantar fasciitis. The dynamic investigation on the foot arch such as walking and running should be carefully observed with integrated insights considering ligaments and foot bones as well as plantar fascia, extrinsic muscles and tendons, and intrinsic muscles and tendons.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.503-515
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• 2011

We developed a walking-assistance robot for walking rehabilitation and assessed the kinematic characteristics of a prototype. The walking-assistance robot is composed of hip, knee, and ankle joints, and each joint is driven by a motor with a decelerator. The equations of angular displacement while walking were derived by theoretically analyzing human locomotion, and the calculated angular displacements were then applied to the robot controller. The output angular displacement of each joint was measured and compared with its input angular displacement in walking experiments on a treadmill at various walking speeds and strides. The differences between the input and output angular displacements are 5.22% for the hip and 2.97% for the knee joints, and it has been confirmed that the walking-assistance robot works well.

• Journal of Korean Physical Therapy Science
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• v.24 no.3
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• pp.1-11
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• 2017

Purpose: The purpose of this study was to investigate the effects of virtual reality based treadmill training on muscle architecture of gastrocnemius in chronic stroke patients. Methods: Thirty chronic stroke patients were randomly assigned to either the virtual reality based treadmill training (VRTT) group (n=15) or treadmill training (TT) group (n=15). Both groups participated in a standard rehabilitation program; in addition, the VRTT group participated in virtual reality based treadmill training for 30 minutes per day, three times per week, for 6 weeks, and TT group participated in treadmill walking training for 30 minutes per day, three times per week, for 6 weeks. Ultrasound image was used for measurement of pennation angle and muscle thickness of the medial gastrocnemius muscle at rest and during maximum voluntary contraction. Results: In the paretic side medial gastrocnemius muscle, greater improvement on the pennation angle and muscle thickness while resting and maximal voluntary contraction were observed in the VRTT group compared with the TT group. Conclusion: Findings of this study demonstrated that the virtual reality based treadmill training has an effect on muscle architecture of medial gastrocnemius in chronic stroke patients.