• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.101-113
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• 2016

Objective: The purpose of this study was to investigate the effect of leg length discrepancy (LLD) on the human body during gait and standing posture. Methods: The study group comprised of 17 adult participants with LLDs of <1 cm. LLDs were artificially induced to 0, 1, 2, and 3 cm. The proportion of weight distribution, shift of the mean center of pressure, and Cobb's angle were measured in the standing position. Kinematic variables such as walking and striding width and time, and the proportion of stance phase for single- and double-limb gait were measured as well. The participants were required to either stand or walk on a treadmill (Zebris FDM) with a pressure plate, and the Cobb's angle measurements were obtained from radiographs. Results: A discrepancy of 3 cm in leg length resulted in a statistically significant shift of the center of pressure in the standing position. Moreover, the Cobb angle increased as the discrepancy became larger. The step length and width of the longer (left) leg during gait statistically significantly increased when the discrepancy was 2 cm. In addition, step time was statistically significant when the discrepancy between the longer (right) and shorter (left) legs was more than 2 cm. The proportion of single-limb stance phase was statistically significant as the discrepancy became larger, especially when the discrepancy was >2 cm for the longer (right) leg and 1 cm for the shorter (right) leg. Conclusion: The study showed that LLD influenced deformations of the human body and walking.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.2
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• pp.1-8
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• 2021

PURPOSE: This study examined the effects of changes in the head direction (forward, upward 10° and downward 10°) on the quadriceps, center of pressure (COP), and foot pressure during squat exercises. The aim was to determine if the head direction could better activate the quadriceps muscle and provide a safer and stable squat posture during squat exercise. METHODS: Fifteen healthy college students were asked to stand on a Zebris, and three electrodes for sEMG were attached to their vastus medialis oblique (VMO), vastus lateralis (VL), and rectus femoris (RF) muscles. The participants then performed squatting exercises under three head directions (forward, upward 10°, and downward 10°). Surface electrodes were then used to record the EMG data during exercise. The Zebris FDM-SX was used to measure the foot pressure and COP of the participants. RESULTS: In squat exercise, the upward head direction group showed significantly higher VL activation than the downward head direction group (p < .05). The upward head direction group showed a significant backward change in the deviation of the COP than the downward and forward groups (p < .05). The upward head direction group showed a significant decrease in forefoot pressure than the downward and forward groups (p < .05) and an increase in the hindfoot pressure compared to the downward and forward groups (p < .05). CONCLUSION: The head direction upward in squat exercise has a positive effect on the quadriceps.

• Physical Therapy Korea
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• v.31 no.1
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• pp.40-47
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• 2024

Background: Single-leg squat (SLS)s are commonly used as assessment tool and closed kinetic exercises are useful for assessing performance of the lower extremities. Pronated feet are associated with foot pressure distribution (FPD) during daily activities. Objects: To compare the FPD during SLSs between groups with pronated and normal feet. Methods: This cross-sectional study included 30 participants (15 each in the pronated foot and control groups) are recruited in this study. The foot posture index was used to distinguish between the pronated foot and control groups. The Zebris FDM (Zebris Medical GmbH) stance analysis system was used to measure the FPD on the dominant side during a SLS, which was divided into three phases. A two-way mixed-model ANOVA was used to identify significant differences in FPD between and within the two groups. Results: In the hallux, the results of the two-way mixed-model ANOVAs revealed a significant difference between the group and across different phases (p < 0.05). The hallux, and central forefoot were significantly different between the group (p < 0.05). Moreover, significant differences across different phases were observed in the hallux, medial forefoot, central forefoot, lateral forefoot, and rearfoot (p < 0.05). The post hoc t-tests were conducted for the hallux and forefoot central regions. In participants with pronated foot, the mean pressure was significantly greater in hallux and significantly lower, in the central forefoot during the descent and holding phases. Conclusion: SLSs are widely used as screening tests and exercises. These findings suggest that individuals with pronated feet should be cautious to avoid excessive pressure on the hallux during the descent-to-hold phase of a SLS.

• The Journal of the Korea Contents Association
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• v.16 no.1
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• pp.734-742
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• 2016

Purpose : The present study was aimed at investigating the plantar pressure on dynamic balance of subjects with functional ankle instability following fatigue of lower leg. Methods : The subjects(30 university students) were divided into 2 groups ; functional ankle instability group(7males and 7females) and ankle stable group(9males & 7females) who could evaluate questionnaire. All the participants were evaluated muscle fatigue of lower leg by Biodex system III and distribution of plantar pressure by Zebris FDM-S system, The dynamic balance was tested by single-leg jump landing. This study were to measure of plantar pressure on dynamic balance with the difference between FAIG and control group following muscle fatigue. Results : In functional ankle instability group(FAIG), the post-fatigue was significantly higher than pre-fatigue in forefoot(p2,p3,p4) of plantar pressure on dynamic balance(p<0.05). The FAIG was significantly higher than the ASG in forefoot(p2, p3, p4) & lat midfoot(p6) of plantar pressure after fatigue in dynamic balance(p<0.05). The FAIG was significantly longer than the ASG in anteroposterior(AP) & mediolateral(ML) distance on center of pressure(CoP) after fatigue in dynamic balance(p<0.05). Conclusion : This study showed that FAIG were effected plantar pressure and center of pressure(CoP) by dynamic balance following muscle fatigue. Further study is needed to measure various age & work with ankle instability for clinical application.

• PNF and Movement
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• v.17 no.3
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• pp.353-368
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• 2019

Purpose: This study investigated the effects of trunk exercise using less-affected extremities on gait and balance in chronic stroke patients. Methods: Thirty subjects with chronic stroke disease were divided into two groups: a trunk exercise group that used less-affected extremities (n=15) and a general trunk exercise group (n=15). All interventions were conducted 30 min a day, 6 times per week, for 3 weeks. Gait parameters were measured before and after the intervention using Zebris FDM-1.5. In addition, all subjects were evaluated using the Trunk Impairment Scale, the Berg Balance Scale, and the Functional Gait Assessment before and after the intervention. Results: Both groups showed improvements on all outcome measured pre- to post-intervention (p<0.05). The groups exhibited significant differences for TIS, BBS, FGA, gait speed, step length, and cadence at post-intervention (p<0.05). Conclusion: This study showed that trunk exercise using less-affected extremities has therapeutic benefits on gait and balance in individuals with chronic stroke disease.

• Journal of Korean Physical Therapy Science
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• v.31 no.1
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• pp.70-87
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• 2024

Background: This study aimed to investigate the effect of Y-balance exercise on spatio-temporal gait parameters in subjects with chronic ankle instability. Design: Randomized Controlled Trial. Method: A study was conducted on 43 people with chronic ankle instability. Subjects performed modified Y-balance exercise 3 times a week for 50 minutes, 4 weeks. Gait parameters were measured using a gait analysis treadmill before exercise, 2 weeks after exercise, and 4 weeks after exercise. A gait analysis treadmill (FDM-T AP1171, Zebris, Germany) was used to measure gait parameters. Mean values were compared using Repeated measured two-way ANOVA. Result:: When comparing the results of three measurements taken before exercise, 2 weeks after exercise, and 4 weeks after exercise, there were significant differences in the qualitative and quantitative aspects of gait in gait variables such as step distance, step time, step ratio, and sway ratio. Conclusions: These results suggest that the Y-balance exercise and various exercises combining balance and proprioception are effective for subjects with chronic ankle instability.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.2
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• pp.63-72
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• 2015

Purpose: The purpose of this study was to investigate the foot pressure of subjects with hallux valgus following conservative management. Methods: The subjects (20 females) were divided into 2 groups; Hallux valgus group (10) and Control group (10) who could evaluate questionnaire & weight bearing X-ray. All the participants were evaluated distribution of foot pressure by Zebris FDM-S system with conservative management (taping therapy and hallux valgus device) during single-limb stance. Results: The Hallux valgus group (HVG) was significantly different than Control group (CG) in hallux valgus angle(p<0.05). The Hallux valgus group with Foot Device (HVG-FD), Hallux valgus group with Taping (HVG-Tp) and Hallux valgus group with Foot device and Taping (HVG-FD&Tp) was not significantly different than CG in hallux valgus angle (p<0.05). The HVG was not significantly different than CG in forefoot (p1, p2, p3), significantly different than CG in rearfoot (p7) about foot pressure during single-limb stance (p<0.05). The HVG-FO and HVG-FO and TP was significantly different than HVG in forefoot (p1, p2, p3), on significantly different than HVG in rearfoot (p7) about foot pressure during single-limb stance (p<0.05). There was significantly correlation HVG-FO and HVG-FO & TP in forefoot (p1, p2, p3) was negative correlation (p<0.05) and in rearfoot (p7) was positive correlation (p<0.05). Conclusion: This study showed that hallux valgus were effected hallux valgus angle and foot pressure by various treatment methods during single-limb stance. Further study is needed to measure various age and work with hallux valgus for clinical application.

• Physical Therapy Rehabilitation Science
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• v.5 no.1
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• pp.34-39
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• 2016

Objective: Hip abductors play a role in providing stability and movement to the lower limbs. The purpose of this study was to examine the effects of hip abductor fatigue on static balance and gait in the general population. Design: One group pre-test post-test design. Methods: Thirteen university students in their twenties volunteered for the study and had underwent a functional assessment. To induce fatigue, the subjects were instructed to raise their dominant lower extremity up against a load of 50% of 1 repetition maximum while producing hip abduction in a side-lying position. Subjects were instructed to maintain an abduction speed of 30 repetitions per minute to induce fatigue. Muscle fatigue was considered to be established when subjects were unable to perform hip abduction three consecutive times along with the metronome. A post-test of balance and gait was performed immediately in order to prevent fatigue recovery. The center of pressure (COP) distance area was measured using the Zebris FDM-S Multifunction Force measuring plate. Gait performance was analyzed using the GAITRite. Results: The COP distance was increased after fatigue was induced. There was a significant increase in the standard deviation of the medio-lateral and antero-posteror distance (p<0.05). Although there was no significant difference in gait parameters, there was a significant decrease in single support time after fatigue was induced (p<0.05). Conclusions: There was an increase in static balance instability and a significant decrease in single support time during gait due to hip abductor muscle fatigue.

• Physical Therapy Korea
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• v.27 no.1
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• pp.78-86
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• 2020

Background: Flat-footed persons with collapsed medial longitudinal arch lose flexibility after skeletal maturity, resulting in several deformities and soft tissue injuries. Although arch support taping is usually applied in the clinic to support the collapsed arch, research on the use of different types of tape for more efficient arch support in flat-footed persons is lacking. Objects: The purpose of this study was to examine three conditions (barefoot, kinesio tape, and dynamic tape) and compare their effects on static and dynamic balance in persons with asymptomatic flexible flatfoot. Methods: Twenty-two subjects (9 females and 13 males) with asymptomatic flexible flatfoot participated in this study. The subjects performed the Y-balance test to measure the composite reach score. The subjects also performed a 30-second standing test to measure the center of pressure (COP) path length and a walking test to measure anteroposterior and lateral variability using the Zebris FDM system. One-way repeated-measures analysis of variance compared the three conditions applied to the subjects' feet for each balance variable. Results: The composite reach score significantly increased following the application of dynamic tape compared with barefoot and that of kinesio tape compared with barefoot. There was no significant difference in the COP path length during standing among the three conditions. Anteroposterior and lateral variability during walking significantly with dynamic tape application compared with barefoot. Conclusion: The results of this study suggest that, in persons with asymptomatic flexible flatfoot, application of kinesio tape and dynamic tape may be effective in increasing the composite reach score in Y-balance test, whereas application of dynamic tape may be effective in reducing anteroposterior and lateral variability during walking.

• The Journal of Korean Physical Therapy
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• v.35 no.2
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• pp.48-52
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• 2023

Purpose: This study was undertaken to determine whether the position of cane use affects the distribution of weight-bearing on both feet of children with hemiplegic cerebral palsy in a standing posture. Methods: Twenty participants with cerebral palsy were recruited as volunteers for this study. Using the Zebris FDM-System, weight-bearing distribution according to the method of using a cane was measured under three conditions in randomized order: (1) standing unaided (no cane); (2) standing with the affected side using the cane; and (3) standing with the non-affected side using the cane. The cane was matched by measuring length-from-floor to the greater trochanter of the subject, and was placed 15 cm outward from the little toe on the supporting side. Results: Evaluating the method of using a cane under the three conditions, we determined that pressure of the foot on the affected side was higher in the order: standing with affected side using cane > standing unaided (no cane) > standing with non-affected side using cane (p<0.05). In the post-hoc analysis, a significant difference was observed between (i) standing unaided (no cane) and standing with the affected side using cane, and (ii) standing with affected side using cane and standing with non-affected side using cane (p<0.05). Conclusion: This study suggests that induced weight-bearing methods using a cane on the affected side could increase the weight-bearing capacity on the affected side in children with spastic hemiplegic cerebral palsy, which will have a positive effect on reducing asymmetry weight support.