• The Journal of Korean Physical Therapy
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• v.23 no.5
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• pp.1-5
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• 2011

Purpose: This study was designed to investigate the changes of postural sway and muscle activation while standing upright and performing a dual task. Methods: Nine healthy adults were recruited and provided their written informed consent. They performed a balance task with and without a cognitive task on a force flatform (Good balance, Metitur Ltd., Filand). Postural sway was measured as medio-lateral and anterior-posterior distance and the velocity of the center of pressure and muscle activations of the ankle dorsi- and plantar-muscle was measured. The recruits completed three trials and the data was analyzed by a paired t-test. Results: There were significant differences in the medio-lateral and anterior-posterior distance and the velocity of the center of pressure, and significant increases in the muscle activities of the tibialis anterior. Conclusion: These findings revealed that performing a dual task increases postural sway and muscle activation of the ankle when simultaneously maintaining balance and performing another cognitive task. Future studies should focus on balance training with a dual task for patients.

• Physical Therapy Korea
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• v.17 no.3
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• pp.20-30
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• 2010

This study examined whether any changes by mental task types on postural control in chronic stroke persons. Sixteen chronic stroke persons (mean age=53.75 yr) and sixteen age-and gender-matched healthy controls (mean age=54.44 yr) took part in this study. Participants randomly performed three different tasks on the stable and unstable surfaces. The no mental task was to stand while holding a 100 g weight in each hand, the arithmetic task (mental task) was to perform a silent 1-backwards counting while standing and holding a 100 g weight in each hand, and the simple task (mental task) was to stand and hold with both hands a tray (200 g) on which a glass filled with water has been placed. Sway path and sway velocity of the center of pressure (COP) were measured to assess standing postural control by task performance using the force platform. According to the results, in stroke group, total sway path and total sway velocity of COP was significantly decreased during arithmetic and simple task compared to no mental task on the stable surface (p<.05), and sway path (anteroposterior AP, mediolateral ML) of COP, total and sway velocity (AP, ML, total) of COP was significantly decreased during arithmetic and simple task compared to no mental task on the unstable surface (p<.05). Especially, sway path (AP, total) of COP and sway velocity (AP, ML, total) of COP was significantly decreased under the simple task when compared to the arithmetic task on the unstable surface (p<.05). In healthy control group, sway path (AP, ML, total) of COP and sway velocity (AP, ML, total) of COP was significantly decreased during arithmetic and simple task compared to no mental task on the stable and unstable surface (p<.05), and sway path (AP, total) of COP and sway velocity (AP, ML, total) of COP was significantly decreased under the simple task when compared to the arithmetic task on the unstable surface (p<.05). In conclusion, the findings of this study showed that arithmetic and simple task improved standing postural control for chronic stroke patients and the type of arithmetic and simple tasks were critical factor that reduced standing postural sway in dual-task conditions. Future research should determine whether dual-task conditions, including simple task, would be effective as a training program for standing postural control of stroke patients.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.3
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• pp.79-84
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• 2017

PURPOSE: The purpose of this study is to examine how task-oriented training focused on lower extremity strengthening can affect mobility function and postural stability. METHODS: The study's subjects included 10 children with cerebral palsy: 7 girls and 3 boys between the ages of 4 and 9 whose Gross Motor Functional Classification System (GMFCS) level was I or II. Their functional mobility was gauged using the Gross Motor Function Measurement (GMFM), and their postural stability was evaluated using a force platform. Participants received task-oriented training focused on lower extremity strengthening for 5 weeks. The study used a paired t-test to investigate the difference in mobility function and postural stability of children with cerebral palsy before and after the lower extremity strengthening exercise. RESULTS: The GMFM dimensions D (standing) (p<.02) and E (walking) (p<.001) improved significantly between the pre-test and post-test. A significant increase in the posturographic center of pressure (CoP) shift and surface area of the CoP were found overall between the pre-test and post-test (p<.001). CONCLUSION: The present study provides evidence that an 8-week task-oriented training focused on strengthening the lower extremities is an effective and feasible strategy for improving the mobility function and postural stability of children with cerebral palsy.

• Physical Therapy Korea
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• v.19 no.3
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• pp.61-71
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• 2012

In daily activities, people often perform two or more tasks simultaneously. This is referred to as dual-tasking or multi-tasking. The purpose of this study was to examine the effects of performing dual tasks while using a mobile phone on static and dynamic postural stability. Twenty-four subjects were asked to stand on a force plate and then instructed to perform a balance task only (BT), a balance task while listening to music (BTL), a balance task while talking on the mobile phone (BTT), and a balance task while sending text messages (BTS). We used the BioRescue$^{(R)}$ to measure postural sway and limit of stability for static and dynamic postural stability. Also the star excursion balance test (SEBT) was used to measure dynamic postural stability. A one-way ANOVA with repeated measures was used to compare the effects of the BT, BTL, BTT, and BTS. The Bonferroni's post hoc test was used to determine the differences among four tasks. Carrying out the BTS significantly decreased the limit of stability compared with carrying out the BT, BTL, and BTT (p<.05). In limit of stability, total surface area of BTT was more significantly decreased than that of BT and total surface area of BTS was more decreased than that of BT, BTL and BTT (p<.05). In the SEBT, the BTS displayed significantly smaller reach distance values compared with the BT or BTL (p<.05). These findings suggest that performing the balance task while sending text message on the mobile phone decreases dynamic postural stability, whereas performing the same task while listening to music using the mobile phone does not. Therefore, it requires more attention to maintain dynamic balance while sending text messages.

• Physical Therapy Korea
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• v.15 no.2
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• pp.11-19
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• 2008

Studies of attentional focus effects, have shown that the performer's attentional focus plays an important role in the performance and learning of motor tasks. We examined the influence of attentional focus on the performance of dual tasks (a postural task and a suprapostural task) and used electromyography (EMG) to examine whether the differences between external and internal focus were also manifest at the neuromuscular level. The subjects (n=40) stood on a balance board (postural task) and held a bar horizontally (suprapostural task). All of the subjects performed under different attentional focus conditions: external (balancer on balance board) or internal (feet) focus on the postural task, and external (balancer on bar) or internal (hand) focus on the suprapostural task. The mean displacement velocity of the bar and the percent reference voluntary contraction (%RVC) of the biceps brachii were reduced when the subjects adopted an external focus on the suprapostural task (p<.05). In addition, the mean displacement velocity of the balance board and %RVC of the tibialis anterior were reduced when the subjects adopted an external focus on the postural task (p<.05). When the subjects adopted an external focus on the suprapostural task, the mean displacement velocity of the balance board and %RVC of the tibialis anterior were also reduced (p<.05). When the subjects' attentional focus was on the postural task, there were no differences in the mean displacement and %RVC of the biceps brachii between attentional focuses. The performance of each task was enhanced when subjects focused on the respective task. The suprapostural task goals had a stronger influence on postural control than vice versa. These results reflect the propensity of the motor system to optimize control processes based on the environmental outcome, or movement effect, that the performer wants to achieve.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3555-3562
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• 2011

The purpose of this study was to investigate the effect of dual task training on postural stability and balance in chronic stroke patients. A total of 25 ambulatory hemiplegic stroke patients were recruited into this study and randomly assigned into two groups, the dual task training group (n=13) and control group (n=12). Both groups received general physical therapy for 30 minutes a day, 5 days a week during 6 weeks. In addition, dual task training group received dual task training programs for 50 minutes a day, 3 days a week during 6 weeks. The scores of Trunk Impairment Scale (TIS), Postural Assessment Scale for Stroke (PASS) and postural sway with eye opened and eye closed on the Force Plate were assessed before and after intervention. Postural stability and balance significantly improved after training in the dual task training group(p<0.05). The result suggests that dual task training is feasible and suitable for individual with chronic stroke.

• The Journal of Korean Physical Therapy
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• v.27 no.5
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• pp.292-298
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• 2015

Purpose: The purpose of this study was to examine the effects of dual tasks on balance and postural control during standing in patients with cerebellar ataxia (CA). It was hypothesized that CA patients would exhibit different sway characteristics of the center of mass (COM) depending on the complexity of the secondary cognitive tasks compared with normal control subjects. Methods: A total of 8 patients with CA and age-matched healthy control subjects participated in this study. They were instructed to perform two balance tasks (non-dual and dual movement) with 3 different complexity of dual tasks. Range, variability, and velocity of COMs were measured. Results: According to the results CA patients showed deficits in balance and postural control with increased dual-task complexity during the static balance task in saggital sway movements. However, there was no significant difference in static balance in frontal sway. With higher difficulty in the cognitive task, CA patients took longer to stabilize their body center, while normal control subjects showed no change between conditions. In addition, CA patients had a greater COM resultant velocity during recovery in the dual-task condition compared with the single-task condition. These findings indicate that CA patients had defendable compensatory strategies in performing dual tasks. Conclusion: In conclusion, CA patients appeared to manage the priority to balance and postural control. Particularly in a situation with a postural threat such as when potential consequences of the loss of stability increase, they appeared to prioritize the control of balance and posture over the performance of the secondary task.

• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.169-177
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• 2013

The purpose of this study is to investigate the effect of aging and dual tasking to the postural control during quiet standing. It was hypothesized that the center of pressure (COP) dynamics would be differently affected by aging and characteristics of the task. Total 60 adults (35 young adults and 25 older adults) participated in this study. They conducted two different standing tasks (dual vs. Nondual) twice in a random order. Variability, complexity, coupling and symmetric index from the left, right and overall COPs were measured by various parameters in nonlinear, linear and frequency analyses methods. Results demonstrated that older adults had worse performance in postural control with decreased complexity in overall sway movement, and increased coupling between left and right limb COP movement, even though there was no significant difference in symmetric index. These tendencies are generally clearer in nonlinear measures at the dual task condition. Results implied that older adults had compensatory strategy in dual tasking which results in simple and combined postural movement patterns.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.21-29
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• 2023

Purpose : Using a smartphone while walking districts attention and increases the risk of losing balance or falling. Ankle instability is caused by decreased muscle strength and decreased neuromuscular ability leading to postural control problems. Dual tasks increases the risk of falls by reducing postural control in adults with ankle instability. This study aimed to investigate the effect of performing a dual task on balance and muscle activity in adults with ankle instability using a smartphone. Methods : Forty-nine individuals with ankle instability participated in this study. A game of finding the wrong picture was performed using a smartphone in the dual task, and only looking at the blank screen of a smartphone was evaluated in the single task. The participants randomly performed single and dual task to evalutate balance and muscle atcitivy. Balance was evaluated using the Biodex balance system (BBS), and muscle activity was evaluated using surface EMG. Muscle activity of the gastrocnemius and tibialis anterior was measured at the same time as balance. Results : The results of this study showed that overall, anteior/posterior, and medial/lateral balance indices all showed significant differences when performing the dual task compared with those during the single task (p<.05). The muscle activity results showed a significant difference compared with that of the gastronemius muscle on the nondominant side during the dual task (p>.05). Conclusion : The results of this study showed that maintaining balance is more difficult when performing the dual task than during the single task, and only the muscle activity of the nondominant gastrocnemius muscle decreased. The dual task causes a decrease in concentration for postural control, which negatively affects postural stability. Individuals with ankle ankle instability should refrain from performing dual tasks, such as using smartphones, to prevent ankle damage.

• Journal of Biomedical Engineering Research
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• v.37 no.1
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• pp.15-20
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• 2016

Essential tremor is a neurological disorder with a tremor of the arms and hands. It is well known that essential tremor is characterized by the postural tremor and the action tremor. There has been no report on the quantitative difference in the characteristics of two tremor types. The purpose of this study was to investigate the possible difference in tremor characteristics of postural and action tremors. Seventeen patients with essential tremor ($68.9{\pm}7.9years$, 7 men, 10 women) participated in this study. Patients performed the tasks of postural maintenance (arms outstretched) and daily actions (spiral drawing). Three-axes (pitch, roll and yaw) gyro sensors were attached on index finger, back of hand and forearm, from which the segment and the joint angular velocities were calculated. Outcome measure was the tremor amplitude defined as the root-mean-square mean of the vector-sum angular velocity at segments and joints. Two-way ANOVA showed that task and joint had main factor on the tremor amplitude (p < 0.05). Post-hoc analysis revealed that tremor amplitude at the metacarpo-phalangeal joint was not affected by task (p > 0.05). However, tremor amplitude at the wrist joint differed among the tasks (p < 0.05), and it was greater in the action tasks than in postural task. Tremor was greater at finger segments than at hand and forearm and it increased in action tasks. The results of this study would be helpful for the understanding and task-specific treatments of the essential tremor.