• The Journal of Korean Physical Therapy
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• v.33 no.6
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• pp.265-271
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• 2021

Purpose: We aimed to analyze the reliability of the test for choice stepping reaction time (CSRT) under an unstable surface and determine whether there were differences in CSRT between support surface conditions (stable vs. unstable conditions) and between age groups (young adults vs. community-dwelling older adults). Methods: Twenty healthy community-dwelling older adults and twenty young adults performed the stepping task under an unstable condition over two visits. The mean of the two trials measured for each visit was used for the analysis. The test-retest reliability was analyzed using intra-class correlation coefficient (ICC) with a 95% confidence interval, standard error of measurement (SEM), and minimal detectable change (MDC). Differences in CSRT between support surface conditions and age groups were analyzed using the independent t-test with Bonferroni correction. Results: Excellent consistency was observed for ICC >0.90 in both groups. Moreover, the SEM and MDC values of the CSRT in older and young adults were 0.03 and 0.09 and 0.01 and 0.04, respectively. There was a significant difference in the CSRT between the age groups under stable (p<0.001) and unstable conditions (p<0.001). Conclusion: The findings demonstrated that the test for CSRT under an unstable condition had reliable results in both groups. Although older adults demonstrated longer reaction times than younger adults in all surface conditions, increasing the balance control demand by implementing a choice stepping task concomitant with a balance task had no influence on the reaction time in both age groups.

• Physical Therapy Korea
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• v.21 no.2
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• pp.28-36
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• 2014

The purpose of this study was to evaluate the changes in the electromyographic (EMG) activity of the trunk and the lower limb muscles during quiet standing on an unstable surface while wearing low-heeled shoes (3 cm), high-heeled shoes (7 cm) and without footwear (0 cm) in 20 young healthy women. The subjects stood on an unstable surface for 30 seconds. We examined the differences in the EMG data of the erector spinae, rectus abdominis, biceps femoris, rectus femoris, tibialis anterior, and the gastrocnemius medialis muscle. A one-way repeated analysis of variance was used to compare the effects of shoe heel height on the EMG activity with the level of significance set at ${\alpha}=.05$. The EMG activity of the erector spinae and the rectus femoris were significantly increased (p<.05) in the subjects who wore elevated heel height, while the tibialis anterior and the gastrocnemius medialis were significantly decreased (p<.05). However, the rectus abdominis and the biceps femoris exhibited no significant difference among the three conditions. The above results indicate that wearing high-heeled shoes may change the postural strategy. The findings of this study suggest that excessive heel height could contribute to an increased fall risk during quiet standing.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.3
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• pp.9-16
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• 2015

Purpose : The purpose of this study was to demonstrate the effects of lumbar stabilization exercise on static and dynamic balance performance with unstable supporting surface and an even surface. Methods : The subjects of this experimental study were 30 patients among hospitalized stroke patients. They were randomly divided into two groups: unstable supporting surface group(USS; n=15) and an even surface group(ES; n=15). The lumbar stabilization exercise program for patients in two groups went through 40 minute exercise sessions three times a week for 8 weeks. To analyze the effects of a variety of supporting surface, Functional reaching test(FRT), Berg's balance scale(BBS), and Overall stability index(static balance) were measured before and after the exercise. The paired t-test was used to compare mean differences between before and after exercis and the independent t-test was used to compare mean differences between groups. Results : After 8 weeks exercise program, there were significant differences between before and after exercise in FRT, BBS, and static balance. But there were not significant differences in balance between two groups. Conclusion : This study suggest that lumbar stabilization exercise on unstable supporting surface and an even surface can improve FRT, BBS, and a static balance.

• Physical Therapy Rehabilitation Science
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• v.5 no.4
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• pp.210-214
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• 2016

Objective: The aim of this study was to measure the muscle architectural parameters of abdominal muscles in healthy individuals by rehabilitative ultrasound imaging (RUSI) and to investigate their changes after bridging exercise in various environments. Design: Cross-sectional study. Methods: The study included 40 healthy participants (19 men, 21 women). Subjects were randomly allocated to a stable surface group (SG, n=20) or an unstable surface group (UG, n=20). The participants assumed three positions in rest, bridging exercise with knee flexion $60^{\circ}$, and bridging exercise with knee flexion $90^{\circ}$ for the measurement of abdominal muscle thickness by RUSI. For the resting position, the participants held the head neutral in a hook-lying position and the dominant side was measured. For contraction, the participants performed the bridging exercise with the knee joint in $60^{\circ}$ and $90^{\circ}$ of flexion for 10 seconds each. Results: For transversus abdominis, external oblique muscle thickness, within the stable surface group and the unstable surface group, no significant contraction difference was observed in both the $60^{\circ}$ and $90^{\circ}$ bridge exercise conditions. Contraction difference of internal oblique muscle was significantly larger at $90^{\circ}$ than at $60^{\circ}$ within the SG (p<0.05). But within the UG, no significant contraction difference was shown. There was no significant contraction difference between the surface group and the unstable SG at $60^{\circ}$ condition and at $90^{\circ}$ condition in all measured muscles. Conclusions: The contraction difference is different for each muscle during bridge exercise with knee flexion $60^{\circ}$ and bridging exercise with knee flexion $90^{\circ}$. Muscle contraction difference is generally large when exercised on an unstable surface than a stable surface, but these are not statistically significant when bridging exercise is performed using dynamic air cushion for unstable surface.

• Physical Therapy Korea
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• v.20 no.3
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• pp.1-8
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• 2013

The purpose of this study was to determine the effectiveness of sit-to-stand training on unstable surfaces in individuals with stroke. Nineteen subjects with chronic stroke were divided into two groups: an experimental group (10 subjects) and a control group (9 subjects). They received 30 minutes of Neuro-developmental therapy (NDT) treatment, and sit-to-stand exercise for 15 minutes three times a week for four weeks. During the sit-to-stand training, the experimental group performed on an unstable AIREX balance pad, but the control group performed on a stable surface. Balance ability and weight-bearing distribution during quiet standing were measured before and after training period using the 7-item Berg balance scale-3P (BBS-3P) and the Five-times-sit-to-stand test (FTSST). In addition, the muscle strength of the knee extensor was evaluated before and after the training period. The results were as follows: 1) The weight-bearing distribution forward of the affected leg, increased significantly in the experimental group after the four-week intervention (p<.05), 2) The 7-item BBS-3P and FTSST increased significantly in the experimental group after the four-week intervention (p<.05), 3) The knee extensor muscle strength in both groups increased significantly after the four-week intervention (p<.05). In conclusion, the results of this study did not show that the sit-to-stand training on an unstable surface was more effective than on a stable surface. However, the results suggested that sit-to-stand training is effective in the balance training of stroke patients.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.1
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• pp.85-92
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• 2022

PURPOSE: This study aimed to analyze the effects of task exercise on an unstable surface on the involuntary arm and leg movement and balance in stroke patients. METHODS: 20 stroke patients were clinically sampled and randomly assigned to two groups of 10 patients each. Experimental group I received task exercise intervention on an unstable surface and experimental group II received task exercise intervention. The interventions were carried out 3 times a week for 4 weeks (30 minutes per session). The global synkinesis (GS) and Berg Balance Scale (BBS) of the patients were evaluated as pre-tests prior to intervention, and then the post-tests were re-measured in the same manner as the pre-tests after a 4-week intervention period. RESULTS: In the experimental group I, there were statistically significant differences in the changes in the arm and leg GS (p < .01) and in the BBS (p < .05). On the other hand, in the experimental group II, there were statistically significant differences in the changes only in the arm GS (p < .01) and in the BBS (p < .05). Also, in the comparison of the changes between the two groups, there was a statistically significant difference in the changes in the leg GS only (p < .05). CONCLUSION: In the experimental group I, the arm and leg GS were statistically significantly reduced, but the balance ability was statistically significantly improved. The reason was that in the experimental group I, similar movements of the paralyzed arm were promoted due to the double-task exercise on the unstable surface, and sensory feedback and posture strategies were well utilized in the legs, which was found to be effective in reducing the GS and improving the balance ability. Therefore, based on these results, the double-task exercise on an unstable surface should be fully utilized for the rapid rehabilitation of stroke patients.

• The Journal of Korean Physical Therapy
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• v.24 no.5
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• pp.300-305
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• 2012

Purpose: This study examined the muscle activity of the trunk muscles during weight shifting exercises on a stable and unstable surface. Methods: Ten healthy young subjects (4 males, 6 females) with no medical history of lower-extremity or lumbar spine disease were enrolled in this study. The muscle activity was recorded using surface electromyography (EMG) electrodes from the both sides of the external obliques and erector spinae muscles. Results: The EMG activities of the both rectus abdominalis, both external obliques and erector spinae muscles were significantly higher when the weight shifting exercise was performed on a firm surface than when a balance pad with a balance ball was used. In weight shifting exercises, the EMG activity of the contralateral external obliques and erector spinae muscles was significantly higher than that of the ipsilateral external obliques and erector spinae muscles under all three support surface conditions. Conclusion: Performing weight shifting exercise using an unstable surface is a useful method for facilitating the trunk-muscle strength and trunk stability.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2852-2854
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• 2005

In this paper, we propose a method to a synchronization of chaotic mobile robots that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a VDP (Van der Pol) equation with an unstable limit cycle. The proposed methods are assumed that if one of two chaotic mobile robot receives the synchronization command, the other robot also follows the same trajectory during the chaotic robot search on the arbitrary surface.

• PNF and Movement
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• v.12 no.4
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• pp.233-241
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• 2014

Purpose: The purpose of this study is to investigate the effects of exercising on a stable and unstable surface for a period of six weeks on the arms of female university students in their twenties. Methods: The subjects consisted of 20 female university students. The experimental group consisted of ten individuals who exercised on an unstable surface, and the control group consisted of ten individuals who exercised on a stable surface. The exercise program was composed of aerobic exercises (i.e. Back and forth movements for clapping and raising cross with both arms) and muscle-strengthening exercises (i.e. Push-ups and raising arms). We measured the subjects before the experiment and after the exercise program using the following measurements tool: a ruler and T-scan plus. The same person measured changes in arm size with a ruler three times and calculated the average to minimize any errors in measurement. We controlled the subjects to measure the amount of arm muscle with a T-scan plus. Twelve hours before the measurements were taken subjects were not permitted to exercise, and four hours before the measurements were taken subjects were not permitted to eat anything. Results: The two groups had no significant difference, but each group felt the effect of the exercise program. Conclusion: There was no difference between the experimental group and the control group. However, it was determined that the exercise had a greater effect on an unstable surface than a stable surface.

• PNF and Movement
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• v.20 no.1
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• pp.67-72
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• 2022

Purpose: The aim of this study was to compare trunk and lower extremity muscle activity during deadlift on stable - and unstable surfaces. Methods: Twenty healthy men participated in this study. The participants performed deadlift exercise on both a stable surface and an unstable surface. During the deadlift, the activities of the trunk and lower extremity muscle were collected by using electromyography. Results: The results showed that the electromyographic activity of the gluteus maximus significantly increased during deadlift on an unstable surface compared to on a stable surface (p <0.05). However, in the electromyographic activities of the rectus femoris, biceps femoris, and erector spinae, there were no significant differences (p >0.05). Conclusion: The finding that the electromyographic activity of the gluteus maximus increases significantly during deadlift on an unstable surface compared to stable one could be used to develop an efficient exercise program.