• Journal of the Ergonomics Society of Korea
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• v.23 no.4
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• pp.1-8
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• 2004

The objective of this study is to identify the effects of material position and physical fatigue on postural stability. Ten male subjects participated in this study. After bicycling exercises, their centers of pressure (COPs) were measured under four material handling positions and four excercise levels. The measured COPs were then utilized to calculate postural sway length in each experimental condition. Subjects' postural stability was quantified using the sway length. Results showed that the effect of different material handling position was significant on the postural sway length in both the posterior-anterior axis and the medio-lateral axis. Results also showed that the postural sway length was increased as physical fatigue accumulated, significantly in subject's posterior-anterior axis. The results imply that bearing a material on the back or front with both hands appeared to cause least sway length and instability.

• Journal of Korean Physical Therapy Science
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• v.17 no.1_2
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• pp.67-76
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• 2010

Background: The purpose of this study was to evaluate the influence of ankle strategy exercise on balance ability in the women of octogenarians. Methods: Ankle strategy exercise group(n=14), leg strengthening exercise group(n=14) were measured an balance ability by Berg Balance Scale(BBS) scores and Balance Performance Monitor(BPM) at pre-intervention and post-intervention in 6weeks. Results: This study were summarized as follows : 1. The BBS scores, sway area, sway path length, sway maximum velocity of ankle strategy exercise group and leg strengthening exercise group were significantly different among the intervention period(p<.05). 2. The improvement of BBS scores, sway area, sway path length, sway maximum velocity were significantly different between ankle strategy exercise group and leg strengthening exercise group at in 6weeks(p<.05). Conclusion: Learned from the ankle strategy exercise could improve BBS scores, sway area, sway path length, sway maximum velocity and a balance for the women of octogenarians. Ankle strategy exercise need to be applied clinically for balance ability of the women of octogenarians.

• PNF and Movement
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• v.16 no.2
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• pp.267-273
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• 2018

Purpose: Leg length discrepancy (LLD) is one of the risk factors for postural imbalance. This study aimed to investigate the effect of induced leg length discrepancy on the limitation of stability (LOS) and static postural balance. Methods: Thirteen adults (males, 7; females 6) participated in this study. The LOS and static postural balance [sway length, sway area, and sway velocity of center of gravity (COG) displacement] were measured by the balance trainer system. The subjects were asked to move the COG for the anterior, posterior, and left and right directions maximally and to keep standing on the platform with and without induced LLD for 30 s in the open and closed eyes conditions, respectively. The LLD was artificially induced to 2 cm using insole. Wilcoxon test was used to compare the LOS and the static postural balance between with and without induced LLD. Results: The anterior and posterior LOS significantly decreased in induced LLD (p<0.05), and the left and right LOS were not significantly different between with and without LLD (p>0.05). Sway length, sway area, and sway velocity of the COG displacement significantly decreased in induced LLD (p<0.05). Conclusion: This study suggests that induced LLD could decease the antero-posterior LOS and increased the static postural balance. Therefore, the LLD could disturb the postural balance.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.2
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• pp.39-47
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• 2020

Postural stability can reduce the likelihood of critical slip and fall accidents in workplaces. The present study aimed to analyze the effect of shoes type on the ability of postural control during quiet standing. The effect of workload on the body balance was also of primary concern. Thirteen healthy male undergraduate students participated voluntarily in the experimental study. Standing on a force plate with wearing slippers, sports shoes, or safety shoes, two-axis coordinate on subjects' center of pressures (COP) was obtained in the two levels, rest and workload. For the workload level, subjects performed treadmill exercise to reach the predetermined level of physical workload. By converting the position coordinates of COPs, the postural sway length in both anterior-posterior (AP) axis and medio-lateral (ML) axis was assessed. ANOVA results showed that, in AP direction, wearing slippers significantly increased the postural sway length compared to wearing sports shoes or safety shoes. No significant difference in the mean sway length in AP axis was observed between sports shoes and safety shoes. In ML direction, both the workload and the shoes type did not significantly affect the mean length of postural sway. However, the postural sway length increased marginally with the slippers especially during the workload condition. This study explains wearing slippers may interfere with the ability of postural control during quiet standing. Physical workload decreases the ability of postural stability further.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.4
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• pp.38-44
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• 2010

We investigated the effects of trunk twist on postural stability during manually handling flat ties. Ten male subjects participated in this study. While handling 5kgf and 10kgf bundles of flat ties respectively, their centers of pressure (COPs) were measured under two levels of body position (twisted and fixed), two levels of direction (left and right), and three levels of object position ($30^{\circ}$, $45^{\circ}$, and $60^{\circ}$). Subjects' postural stability was quantified by calculating the sway length. Results showed that the effect of different object position was significant on postural sway length in subject's medio-lateral axis. Post-hoc multiple comparions revealed that, under the 5kgf load condition, the sway length was increased significantly as the object position increased to $45^{\circ}$. Under the 10kgf load condition, however, the sway length was increased significantly at the object position of $60^{\circ}$. Actual or potential applications of this research include guidelines for the design of working posture evaluation techniques.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.16-23
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• 2018

Postural instability can increase the likelihood of hazardous slip and fall accidents in workplaces. The present study intended to extend understanding of the effect of abnormal neck posture on postural control during quiet standing. The effect of body fatigue on the postural control was also of primary concern. Twelve healthy undergraduate students volunteered to participate in the experiment. Standing on a force platform with the neck neutral, flexed, extended, or rotated, subjects' center of pressures (COP) were measured under the two levels of body fatigue. For the fatigue condition, Subjects exercised in a treadmill to meet the predetermined level of body fatigue. Analyzing the position coordinates of COPs, the length of postural sway path was assessed in both medio-lateral (ML) axis and anterior-posterior (AP) axis. Results showed that, in AP direction, neck extension or rotation significantly increased the sway length as compared with neck neutral. Neck extension led to greater sway length compared to neck rotation. Neck flexion did not differ from neck neutral. The sway length in the AP direction also became significantly larger as the body fatigue accumulated after treadmill exercise. In ML direction, as compared to neutral posture, the neck extension, flexion, or rotation did not significantly affect the length of postural sway path. However, the sway length seemed to increase marginally with the neck extended during the fatigued condition. This study demonstrates that abnormal neck posture may interfere with postural control during standing. The ability to maintain postural stability decreases significantly with the neck extended or rotated. Body fatigue leads to postural instability further.

• Journal of the Ergonomics Society of Korea
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• v.25 no.3
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• pp.1-15
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• 2006

Loss of postural balance can possibly lead to increased risk of slips and falls in work places. Present study was performed to investigate the effects of noisy environments on postural stability during standing. It is known that a sound is characterized by the frequency and pressure level of the sound. Therefore, effects of the frequency and pressure level on postural stability were of primary concern. Ten male subjects participated in the experiment. Subject's center of pressure(COP) position was collected on a force plate while they were exposed to different frequency and pressure levels of the sound. Measured COP was then converted into the length of postural sway path in both anterior-posterior(AP) and medio-lateral(ML) axis. Results showed that the length of sway path in AP axis was significantly affected by the frequency of sound. The length of sway path was lowest at frequency level of 2000Hz and increased below and above this frequency range. The sound pressure level, however, did not significantly affect the postural sway length in both AP and ML axis. The results imply that industrial workers in noisy environments should be aware that their abilities of postural balance can be disturbed significantly.

• The Journal of Korean Physical Therapy
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• v.31 no.5
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• pp.273-278
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• 2019

Purpose: The purpose of this study was to investigate the effects of three-dimensional virtual reality horse riding simulator training using a head-mounted display on gait and balance in children with cerebral palsy. Methods: Ten children with cerebral palsy were randomly assigned to the horse riding simulator (HRS) group (n=5) or the horse riding simulator with virtual reality (HRSVR) group (n=5). To evaluate balance, center of gravity (COG) sway velocity and total sway distance of each group were assessed using the Wii balance board, and gait speed and stride length of each group were assessed using a gait analysis system. Results: Intra-group comparisons between pre- and post-intervention measures revealed that there were significant changes in all gait and balance variables such as stride length, gait velocity, COG sway velocity and COG sway distance in the HRSVR group (p<0.05). In the HRS group, there were significant changes in all variables except stride length (p<0.05). In addition, inter-group comparisons showed significant differences between the two groups in stride length, gait velocity and COG sway distance except COG sway velocity (p<0.05). Conclusion: The findings of this study suggest that horse riding simulator training combined with 3D virtual reality can be a new positive therapeutic approach for improving functional performance in children with cerebral palsy.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.4
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• pp.1631-1635
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• 2018

Stroke can cause leg weakness, sensory abnormalities, and balance disorders. The purpose of this study was to investigate the effect of elastic taping on postural sway in patients with stroke. This study randomly applied elastic taping to 20 patients with stroke in two ways. The center of pressure (COP) distribution was measured before and after the elastic taping. The measurement variables were COP area and length, and measurements were performed immediately after taping. The elastic taping on tibialis anterior muscle showed a significant decrease in COP area and length compared to that without elastic taping. The elastic taping on gastrocnemius muscles showed a significant decrease in COP area and length compared to that without elastic taping. There was no significant difference in COP area and length between the elastic taping on tibialis anterior muscle and gastrocnemius muscles. Our results suggested that applying elastic taping on the ankle joints is effective in decreasing postural sway after in patients with stroke.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.4
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• pp.146-152
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• 2008

This study was aimed to understand the effects of perturbed floor surface on human postural stability while standing. Ten subjects were asked to stand quietly on the surface with two angles of inclination ($0^{\circ}$ and $5^{\circ}$), two contamination conditions (dry and oil-contaminated), and three commercial floor materials (ceramic tile, coated wood, and vinyl tile). During each trial, a force plate with data acquisition systems was used to collect subject's center of pressure (COP) position. Measured COPs were then converted into the length of postural sway path in both subject's anterior-posterior (AP) and medio-lateral (ML) axis. Results showed that the length of sway path in ML axis was significantly affected by the angle of inclination and the type of floor material. The sway length was increased significantly at the inclination angle of $5^{\circ}$ and on the vinyl tile, respectively. The contamination condition, however, did not significantly affect the postural sway length in both AP and ML axis. The results imply that a proper treatment of floor surface and material is critical to preserving postural balance while standing.