• ETRI Journal
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• v.42 no.1
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• pp.46-53
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• 2020

Gait analysis is an effective clinical tool across a wide range of applications. Recently, inertial measurement units have been extensively utilized for gait analysis. Effective gait analyses require good estimates of heel-strike and toe-off events. Previous studies have focused on the effective device position and type of triaxis direction to detect gait events. This study proposes an effective heel-strike and toe-off detection algorithm using a smart insole with inertial measurement units. This method detects heel-strike and toe-off events through a time-frequency analysis by limiting the range. To assess its performance, gait data for seven healthy male subjects during walking and running were acquired. The proposed heel-strike and toe-off detection algorithm yielded the largest error of 0.03 seconds for running toe-off events, and an average of 0-0.01 seconds for other gait tests. Novel gait analyses could be conducted without suffering from space limitations because gait parameters such as the cadence, stance phase time, swing phase time, single-support time, and double-support time can all be estimated using the proposed heel-strike and toe-off detection algorithm.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.3
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• pp.95-100
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• 2015

PURPOSE: The purpose of this study is to investigate the effects of the angles of the knee and heel-off on the muscle activity during a bridge exercise. METHODS: 15 healthy adult men and women with the balance ability and joint working range required for performing a bridge exercise participated in this study, in which $120^{\circ}$, $90^{\circ}$ and $60^{\circ}$ angles of the knee-flexion and heel-off were applied during the bridge exercise. RESULTS: Our data showed that there were significant differences in muscle activities of elector spinae and rectus abdominis when $120^{\circ}$ and $60^{\circ}$ angles of the knee were applied, of internal oblique when $120^{\circ}$ and $60^{\circ}$ were applied, and external oblique when $90^{\circ}$ and $60^{\circ}$ were applied. When heel-off was applied, there were significant differences in muscle activities of elector spinae and rectus abdominis when $120^{\circ}$ and $60^{\circ}$ were applied, of internal oblique when $120^{\circ}$ and $60^{\circ}$ were applied, and external oblique when $90^{\circ}$ and $60^{\circ}$ were applied. CONCLUSION: In this study on an application of heel-off to the bridge exercise, we showed that the effect of the angles of the knee on the muscle activities of elector spinae, rectus abdominis, internal oblique and external oblique were all similar to the regular bridge exercise, but overall muscle activities were increased with heel-off when compared with the regular bridge exercise.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.1
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• pp.1398-1405
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• 2018

The purpose of this study was to investigate the effect of heel off stairway walking exercise on the increase of muscle activity and balance activity of the ankle joint muscles in university students with functional ankle instability. The conservative treatment for the control group consisted of stairway walking (n=10) and the experimental group consisted of heel off stairway walking (n=11). The therapeutic intervention of the control and experimental groups was performed a total of 12 exercise sessions, 3 times per week for 4 weeks. To compare the two groups, the level of ankle disability was assessed by using the EMG, BT4 and Pedoscan in pre-treatment and post-treatment. Muscle activity increased in both the experimental groups and control groups in each group, however there was no significant difference between the groups. Balance ability did not show any significant difference. This study demonstrates that heel-off stairway walking is effective in significantly increasing muscle activity, however did not significantly improve balance ability.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.117-123
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• 2021

The purpose of this study is to convergence comparison the ankle joint angle change during walking of college students in their 20s with flat foot according to the heel height of insole shoes. Qualisys Track Manager Software ver. 2.8 (Qalisys Track Manager) was used for 15 college students. Functional shoes with insoles were manufactured, and the heel heights of the shoes were set to 3cm and 7cm. The subjects wore shoes with two high heels and gaited by attaching a reflex marker to the side of the ankle joint. The angle change of the ankle joint was measured in the gait stance phase. The angle of the ankle joint significantly decreased both heel strike, foot flat, midstance, and toe off to the heel height increased when the subjects with flat feet wore insole shoes. Therefore, it is thought that flat feet should wear low shoes when wearing insoles to reduce the fatigue of the soles and to walk comfortably.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.69-81
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• 2005

In this study using two-dimensional system of the analysis of image, when normal males in their twenties who have normal foot and step with heel first are walking and running, they who are wearing running shoes or barefoot are testing and comparing the exchange factors of heel control. There are following results of this test by verifying them with T-Test. 1) When they are running, there are two big different gap which is $6.05^{\circ}$ between barefoot and wearing the running shoes. The former is $174.79^{\circ}{\pm}6.31$ and the latter is $180.84^{\circ}{\pm}4.69$. But it is not statistically significant. The angle of first step with heel is $100.42^{\circ}{\pm}3.95$ with barefoot and $93.97^{\circ}{\pm}094$ with wearing the running shoes. In this case, it is statistically significant(p<.01) 2) When they are running, the angle of the Achilles' tendon has different gap which is $5.24^{\circ}$ between barefoot and wearing the running shoes. The former is $179.70^{\circ}{\pm}4.23$ and the latter is $184.94^{\circ}{\pm}4.09$. It is not statistically significant. The angle of minimal step with heel is $96.30^{\circ}{\pm}3.07$ with barefoot and $90.84^{\circ}{\pm}0.44$ with wearing the running shoes. In this case, it is statistically significant(p<.01). 3) In the angle of the Achilles' tendon and the angle of first step with heel, when they are walking, the angle of the Achilles' tendon has different gap which is $1.81^{\circ}$ between barefoot and wearing the running shoes. The former is $6.39^{\circ}{\pm}0.83$ and the latter is $8.20^{\circ}{\pm}1.85$. It is not statistically significant. The angle of first step with heel is $2.32^{\circ}{\pm}0.51$ with barefoot and $3.22^{\circ}{\pm}1.44$ with wearing the running shoes. It is not statistically significant. 4) In the angle of the take-off of Achilles' tendon, when they are walking, the angle of the take-off of Achilles' tendon has different gap which is $3.88^{\circ}$ between barefoot and wearing the running shoes. The former is $177.62^{\circ}{\pm}8.78$ and the latter is $173.74^{\circ}{\pm}16.31$. It is statistically significant(p<.05). Therefore, they are running, the angle of the take-off of Achilles' tendon is $178.37^{\circ}{\pm}19.28$ with barefoot and $171.26^{\circ}{\pm}12.18$ with wearing the running shoes. It is statistically significant(p<.05).

• The Journal of Korean Physical Therapy
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• v.19 no.6
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• pp.11-15
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• 2007

Purpose: This study examined the various patterns of standing to squatting activities, and reports the testing standard and phases for examining the standing to squatting position. Methods: One thousand, normal college students (500 males, 500 females) volunteered for this study. The patterns are performed by naked eye analysis with two video cameras. Results: The patterns from the standing to squatting position are as follows 1. parallel with the heel on the pattern: 2. parallel with the heel off the pattern: 3. closed with the heel on the pattern: 4. closed with the heel on the pattern: 5. open with the heel on the patternand 6. open with the heel on the pattern. Conclusion: The phases of the standing to squatting position are as follows: phase I from standing to the anterior parts of the knees reaching the anterior limit of the BOS, phase II from phase I until the height of the hip and knee joints are the same, phase III from phase II until there was no full squatting and the heels broke contact with the floor and phase IV from phase III full squatting on the heels in contact with the floor.

• Journal of the Korean Society of Safety
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• v.23 no.1
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• pp.35-45
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• 2008

This study was performed to compare the kinematics among three different safety shoes(type 1: ergonomically designed and high quality shoes, 2: curved and cushioned safety shoes, and 3: regular safety shoes) and to find the effect of insole during walking. Ten healthy subjects were recruited for this study. The range of motion of knee and ankle joint, angle of rear foot and angle of heel contact were measured using a three dimensional motion analysis system. In the second peak, the angle of heel contact showed statistically significant difference between safety shoes and insole, however, there was no statistical significance among three different safety shoes. The angle of ankle increased significantly at initial contact, first peak, the second peak and the toe off phase compared with type 1 and 2 safety shoes, and the angle of ankle showed statistically significant difference between with and without applying the insole. During the first peak, the second peak and the toe off phase, the angle of knee was statistical significance between safety shoes and insole. In heel contact, the angles of Achilles' tendon showed statistically significant difference between safety shoes and insole. The rear foot angles showed statistically significant difference between safety shoes and insole during heel contact and early heel contact. These results suggest that the type 1 safety shoes were superior to others in the statistics, and applying insole could be a possible method to prevent fatigue of lower extremity and musculoskeletal disorders. Further studies are needed to find the effect of ergonomically designed safety shoes and insole on practical value in prevention of musculoskeletal disorder, fatigue and satisfaction of workers.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.225-233
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• 2013

The purpose of this study was to estimate the potential injury via analyzing ground reaction force components that were resulted from a prolonged-run-induced fatigue. For the present study, passive and active components of the vertical ground reaction force were determined from time and frequency domain. Shear components of GRF also were calculated from time and frequency domain. Twenty subjects with rear foot contact aged 20 to 30, no experience in injuries of the extremities, were requested to run on the instrumented tread-mill for 160 minutes at their preference running speed. GRF signals for 10 strides were collected at 5, 35, 65, 95, 125, and 155 minute during running. In conclusions, there were no significant difference in the magnitude of passive force, impact load rate, frequency of the passive and active components in vertical GRF between running times except the magnitude of active force (p<.05). The magnitude of active force was significantly decreased after 125 minute run. The magnitude of maximum peak and maximum frequency of the mediolateral GRF at heel strike and toe-off have not been changed with increasing running time. The time up to the maximum peak of the anteroposterior at heel-strike moment tend to decrease (p<.05), but the maximum peak and frequency of that at heel and toe-off moment didn't depend significantly on running time.

• The Journal of Korean Physical Therapy
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• v.15 no.2
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• pp.196-209
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• 2003

본 연구의 목적은 보통 보행과 장애물 보행 시작시에 accuracy constraints, 즉 발꿈치 닿기(swing limb heel-strike)의 정확도가 힘판(forceplate) 상에서 힘의 조절 (force modulation)과 EMG에 어떠한 영향을 미치는지를 분석하는 것이다. 본 실험의 대상자는 힘판(forceplate)위에서 보통 보행과 장애물 보행을 하되, 대상자 앞에 놓인 표적(target)에 정확히 발꿈치 닫기 (heel-strike)를 하도록 유도되었다. 이 때 힘판 자료와 전경골근(tibialis anterior)및 가자미근 (soleus)의 근전도 (EMG)의 활동을 양쪽 다리에서 측정하였다. 대상자 앞에 놓인 표적 (target)에 정확한 발꿈치 닫기(heel-strike)가 요구되었을 때에는 발끝밀기(swing toe-off) 시간이 증가되었으며 힘판(forceplate)상에서의 peak farce와 slope to peak force 가 감소되는 것으로 나타났다. 전경골근 (tibialis anterior)의 활동역시 큰 차이로 감소하는 것으로 나타났다. 하지만 보통 보행과 장애물 보행시의 근전도 혹은 힘판상의 자료에는 큰 차이점이 없는 것으로 나타났다. 이러한 결과는 기존의 상지(upper extremity)에서 보여준 운동제어 (motor control)의 이론들이 하지(lower extremity)에서도 동일하게 적용될 수 있음을 보여주는 것이다.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.733-738
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• 2014

We propose a new approach called as a peak time approach for faster detection of step initiation for the lower limb exoskeleton. As faster detection of step initiation is an important criterion in evaluating the lower limb exoskeleton, many studies have investigated approaches to detect step initiation faster, including using electromyography, the center of pressure, the heel-off time and the toe-off time. In this study, we will utilize vertical ground reaction force events to detect step initiation, and compare our approach with prior approaches. Additionally, we will predict the first step's heel strike time with vertical ground reaction force events from multiple regression equations to support our approach. The lower limb exoskeleton should assist the operator's movement much faster and more reliably with our approach.