• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.762-770
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• 2021

The purpose of this study was to analyze the effect on the vertical ground reaction force, the elapsed time, and the center of pressure factors during gait by maepsi exercise program, which is a whole body exercise, to middle-aged women for 8 weeks. A total of 25 subjects participated in this study, 13 in the exercise group(age, 41±4.4 years; heigh, 162.5±5.8cm; weight, 57.8±6.7kg; body mass, 21.9±2.4kg/m2) and 12 in the control group(age, 41.1±5.6 years; height, 160.9±5.5 cm; weight, 576.2±8.1 kg; body mass, 21.7±2.9 kg/m2). In the exercise group, the maepsi exercise program consisting of 7 areas, 23 types and 77 movements, was conducted 3 times a week for 8 weeks. Two-way repeated measures ANOVA was performed to verify the ground reaction force factors during gait, and the post-test was analyzed with bonferroni adjustment(a=.05). In the exercise group, compared to the control group, the exercise group showed higher values than the control group in the elapsed time to FMWA and FPO, vertical ground reaction force at FMWA and FPO, and RMS factors of COP in the AP direction. Therefore, it was found that the 8-week maepsi exercise program improved the acceleration and deceleration exercise functions of middle-aged women who performed gait.

• The Journal of Korean Physical Therapy
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• v.10 no.1
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• pp.127-138
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• 1998

This study was carried out tn invstigate and compare biomechanical characteristics during free speed gait in hemiplegic patients after stroke who took therapeutic exercise by analyzing kinematic and kinetic data in the sagital plane and electromyographic data. Six patients($41\~69$ years old) and age-matched six volunteers in good health(51-61 years old) wire studied. The patients were sorted into two groups, depending on their self-speed of walking : fast speed group(3 patients) and slow speed group(3 patients). The results were as fellows. : 1. In spatio-temparal parameters, affected and unaffected side of fast group showed symetry but blew group showed asymetry of single limb support, opposite foot contact and stance phase (p<0.05). Compared with normal group, patient group showed slower velocity, shoter stride length and longer double limb support (p<0.05). 2. In the pelvic anterior tilt, patient group showed lower valued than normal group. It. In the ground reaction force-vertical force, fast group showed similar double peak gragh compared with normal group, butvslow group showed lower values without double peak (p<0.05).

• Physical Therapy Korea
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• v.23 no.1
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• pp.72-79
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• 2016

Background: Increased foot pronation causes biomedchanical changes at the lower limbs, which may result in musculoskeletal injuries at the proximal joints. Pronation rear-foot leads to plantar fasciitis, Achilles tendonitis, and posterior tibial tendonitis pathologically. According to the recent meta-analysis, They showed that therapeutic adhesive taping is more effective than foot orthoses and motion control footwear, low-Dye (LD) taping has become the most popular method used by physiotherapists. Objects: The purpose of this study was to determine the immediate effects of LD taping results in different ankle motion and ground reaction force (GRF) as before and after applied LD taping on pronated rear-foot during gait. Methods: Twenty-four participants were recruited for this study. The gait data were recorded using an 8-camera motion capture system and two force platforms. At first, the experiments were carried out that participants walked barefoot without LD taping. And then they walked both feet was applied LD taping. Results: The ankle inversion minimum was significantly greater after LD taping than before LD taping (p=.04); however, in the GRF, there were no significant differences in the inversion maximum or total motion of the stance phase (p=.33, p=.07), or in the vertical (p=.33), posterior (p=.22), and lateral (p=.14) peak forces. Conclusion: The application of taping to pronation rear-foot assists in increased ankle inversion.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.3
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• pp.21-27
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• 2021

PURPOSE: This study examined the relationship between the severity of a hallux valgus (HV) deformity and the kinetic three-dimensional ground reaction force (GRF) through a motion analysis system with force platforms in individuals with a HV deformity during normal speed walking. METHODS: The participants were 36 adults with a HV deformity. The participants were asked to walk on a 6 m walkway with 40 infrared reflective markers attached to their pelvic and lower extremities. A camera capture system and two force platforms were used to collect kinetic data during gait. A Vicon Nexus and Visual3D motion analysis software were used to calculate the kinetic GRF data. RESULTS: This research showed that the anterior maximal force that occurred in the terminal stance phase during gait had a negative correlation with the HV angle (r = -.762, p < .01). In addition, the HV angle showed a low negative correlation with the second vertical maximal force (r = .346, p < .05) and a moderate positive correlation with the late medial maximal force (r = .641, p < .01). CONCLUSION: A more severe HV deformity results in greater abnormal translation of the plantar pressure and a significantly reduced pressure force under the first metatarsophalangeal joint.

• Korean Journal of Applied Biomechanics
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• v.28 no.1
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• pp.29-35
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• 2018

Objective: The purpose of this study was to determine the asymmetry of vertical ground reaction force (GRF) components between dominant and non-dominant legs in rested and fatigued states in prolonged running. Method: Twenty healthy men, heel strikers, were included (age: $24.00{\pm}5.0years$; height: $176.1{\pm}6.0cm$; body mass: $69.0{\pm}6.0kg$) in this study. Subjects ran on an instrumented treadmill for 130 minutes. During treadmill running, GRF data (1,000 Hz) were collected for 20 strides at five minutes (rested) and 125 minutes (fatigued) running while they were unaware of collecting data. Asymmetry indexes (ASI) were calculated to quantify the asymmetry magnitude in rested and fatigued states. Paired t-test was used to verify the differences between dominant and non-dominant legs in rested and fatigued states. In addition, one-way repeated measure analysis of variance was applied for comparison of ASI of both states. The level of significance was set at p < .05. Results: Passive force peak magnitude, loading rate, and impulse affecting the development of running injury were found significantly greater in dominant leg than in non-dominant leg at rested state (p < .05). However, passive force peak time and active force peak magnitude were found significantly different between legs in fatigued state (p < .05). To determine changes in percentage of asymmetry between legs in both states, ASI was used. ASI for all variables increased in fatigued state; however, no significant differences were found between both states. Conclusion: This study found that fatigue did not affect differences in vertical GRF between dominant and non-dominant legs and asymmetry changes.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.141-147
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• 2017

Objective: We obtained force-displacement curves for countermovement jumps of multiple heights and examined the effect of an arm swing on changes in vertical jumping strategy. Countermovement jumps with hands on hips (Condition 1) and with an arm swing (Condition 2) were evaluated to investigate the mechanical effect of the arm movement on standing vertical jumps. We hypothesized that the ground reaction force (GRF) and/or center of mass (CoM) motion resulting from the countermovement action would significantly change depending on the use of an arm swing. Method: Eight healthy young subjects jumped straight up to five different levels ranging from approximately 10% (~25 cm) to 35% (~55 cm) of their body heights. Each subject performed five sets of jumps to five randomly ordered vertical elevations in each condition. For comparison of the two jumping strategies, the characteristics of the boundary point on the force-displacement curve, corresponding to the vertical GRF and the CoM displacement at the end of the countermovement action, were investigated to understand the role of arm movement. Results: Based on the comparison between the two conditions (with and without an arm swing), the subjects were grouped into type A and type B depending on the change observed in the boundary point across the five different jump heights. For both types (type A and type B) of vertical jumps, the initial vertical force at the start of push-off significantly changed when the subjects employed arm movement. Conclusion: The findings may imply that the jumping strategy does change with the inclusion of an arm swing, predominantly to modulate the vertical force advantage (i.e., the difference between the vertical force at the start of push-off and the body weight).

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.259-274
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• 2005

The purpose of this study was to compare the kinematic and kinetic parameters of lower extremity joints between novice and experienced sports aerobic dancers during two heights of depth jumps. Four male dancers were participated in this study and they performed 40cm and 60cm height depth jump three times, respectively. Four ProReflex MCU cameras (100frame/sec) and a Kistler force plate (1000Hz) were used for data collection. The results indicated that the duration of contact phase of experienced group was shorter than that of novice group regardless of jump height. For minimum angle of hip, knee, and ankle joints, the novice group had tendency to decrease the angle but the experienced group had increased the joint angle with jump height. There was no difference of total ground reaction force between the groups but the reaction force had tendency to increase with jump height. Thus, this study implied that repetition of jump and landing may induce joint related injury and further study such as. EMG analysis of lower extremity can be needed to verify the relationship between injury and ground reaction force.

• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.519-528
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• 2009

The effects of taping on the use of such measures for prevention have already been comprehensively described in the literature. However, few studies have analyzed ground reaction forces and postural stability with functional ankle instability subject during dynamic activities with ankle taping The purpose of this study was to identify the effects of ankle taping on ground reaction force and postural stability during jump landing. Fourteen players who has ankle instability were participated in this study. we used vicon and force platform. The application of taping who has ankle instability decreased DF and inversion angular velocity and peak vertical ground reaction force during landing. It also improved A-P cop, M-L cop in stability. The findings of this study support the use of taping as part of injury prevention for subject with functional ankle instability in clinical setting.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.265-272
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• 2016

Objective: The aim of this study was to analyze X-factor, triple X-factor, and the center of pressure (COP) according to the feel of golf driver swing. Method: For this research, 9 golfers from the Korea Professional Golfers' Association (age: $30.11{\pm}2.98yrs$, height: $178.00{\pm}8.42cm$, weight: $76.22{\pm}8.42kg$, experience: $10.06{\pm}3.11yrs$) were recruited to participate in the experiment. Twelve Motion Analysis Eagle-4 cameras were installed and an image analysis was conducted by using the NLT (non-linear transformation) method, and 2 units of Kistler type 5233A dynamometer were used to measure ground reaction force. The sampling ratio was set at 1000 Hz. The golfers each took 10 swings by using their own driver, and chose the best and worse feel from among 10 shots. A paired-sample t-test was used to analyze the results. Results: In regard to feel, no change in head speed, X-factor, and the triple X-factor's X-factor stretch, hip rise, and head swivel, was observed (p>.05). Regarding ground reaction force, a difference was observed between the top of the backswing (p<.05) and impact (p<.05) in the vertical force of the left foot. For COP, a difference was also observed between the mid backswing (p<.001), late backswing (p<.001), and top of the backswing (p<.05) for the right foot X-axis and Y-axis mid follow through (p<.01). Conclusion: It can be reasoned that, irrespective of feel, the head speed, X-factor and triple X-factor's X-factor stretch, hip rise and head swivel did not have an effect on drive distance for domestic golfers, and the vertical reaction force of the left foot and left-right movement span's pressure dispersal of the right foot had an increasing effect on drive distance.

• 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.