• 한국운동역학회지
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• 제18권1호
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• pp.107-115
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• 2008

본 연구의 목적은 다운증후군 아동들의 점프와 착지 능력 향상을 위해 다운증후군 아동의 점프와 착지 동작 수행 시 지면반력과 근육 활동을 규명하는 것이다. 다운증후군 아동 6명과 정상아동 1명이 수직 점프 후 착지 동작을 수행하였으며, 대퇴이두근, 대퇴직근, 전경골근 및 비복근의 근육활동과 지면반력이 분석되었다. 다운증후군 아동들은 점프 동작 수행 시 추진구간에서 비복근을 제대로 사용하지 못하는 것으로 나타났다. 이러한 비복근의 소극적인 활동은 다운증후군 아동의 발 앞꿈치 이지 전 0.3초 동안 충격량이 정상아동에 비해 작게 나타난 결과와 일치한다. 다운증후군 아동의 제 2 수직지면반력은 정상 아동에 비해 늦게 나타나, 다운증후군 아동들은 건강한 아동에 비해 무릎을 더 많이 굴곡시켜 착지했음을 알 수 있다. 다운증후군 아동의 제 1 및 제 2 수직지면반력, 다운증후군 아동 D3을 제외한 다운증후군 아동의 제 2부하율은 정상아동 보다 작게 나타났다. 운동기술이 저하된 다운증후군 아동은 착지 시 지면으로부터 발생되는 충격을 흡수하는 능력이 정상아동에 비해 떨어지는 것으로 나타났다.

• 재활복지공학회논문지
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• 제10권1호
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• pp.47-57
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• 2016

본 연구에서는 다자유도 동적 하네스 시스템을 개발하고 동적 하네스 체중지지에 따른 인체 영향평가를 하고자 한다. 건강한 성인 남성 20명을 대상으로 실험을 진행하였으며 평지보행, 앉기, 서기, 계단 오르기, 계단 내려오기 5가지 일상생활 동작을 수행하였다. 일상생활 동작 수행 시 각 피험자 체중의 0%, 30%, 50%에서의 근육 활성도와 족압 분포를 측정하였다. 근육 측정부위는 대퇴직근, 대퇴이두근, 전경골근, 외측 비복근이다. 하네스 체중지지율 증가에 따라 족압의 평균값은 전체적으로 감소하는 경향을 보였다. 평지보행에서는 체중지지율 증가에 따른 전족부의 압력의 감소폭이 크게 나타났으며 비복근과 대퇴이두근의 활성 감소를 보였다. 앉기 동작에서는 후족부의 족저 압력 감소폭이 크게 나타났으며 체중지지율에 따라 전경골근의 근육 활성이 감소하였다. 계단 내려오기 동작에서는 체중지지율 증가에 따라 전족부의 압력이 크게 감소하였고 대퇴직근의 활성감소가 크게 나타났다. 의자에서 일어나기동작과 계단 오르기 동작에서는 동적 하네스 체중지지효과가 미비하였으며 이는 속도가 건강한 성인 남성의 동작 수행 속도보다 느리기 때문이다. 후속 연구에서는 본 시스템을 개선하기 위한 연구가 지속되어져야 할 것이다.

• 한국운동역학회지
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• 제24권2호
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• pp.139-149
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• 2014

The purpose of this study was to evaluate the effect of angle change of forefoot's adhesive outsole on the electromyographic activity (EMG) of the erector spinae and selected lower limbs muscle during downhill walking over $-20^{\circ}$ ramp. Thirteen male university students (age: $25.4{\pm}3.9$ yrs, height: $176.2{\pm}5.1$ cm, weight: $717.4{\pm}105.0$ N) who have no musculoskeletal disorder were recruited as the subjects. To assess the myoelectric activities of selected muscles, six of surface EMG electrodes with on-site pre-amplification circuitry were attached to erector spinae (ES), rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), lateral gastrocnemius (LG), and medial gastrocnemius (MG). To obtain maximum EMG levels of the selected muscles for normalization, five maximum effort isometric contraction were performed before the experimental trials. Each subject walked over $0^{\circ}$ and $20^{\circ}$ ramp with three different forefeet's EVA outsole (0, 10, $20^{\circ}$) in random order at a speed of $1.2{\pm}0.1$ m/s. For each trial being analyzed, five critical instants and four phases were identified from the recording. The results of this study showed that the average muscle activities of MG and LG decreased in $20^{\circ}$ shoes compared to $0^{\circ}$ and $10^{\circ}$ ones in the initial double limb stance (IDLS). In initial single limb stance (ISLS) phase, the average muscle activities of ES increased with the angle of forefoot's adhesive outsole, indicating that the increment of shoes' angle induce upper body to flex anteriorly in order to maintain balance of trunk. In terminal double limb stance (TDLS) phase, average muscle activities of TA significantly increased in $20^{\circ}$ outsole compared to $0^{\circ}$ and $10^{\circ}$ ones. There was no external forces acting on the right foot other than the gravity during terminal single limb stance (TSLS) phase, all muscles maintained moderate levels of activity.

• 동의생리병리학회지
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• 제19권5호
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• pp.1356-1362
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• 2005

The purpose of this study os to investigative the effect of Carrageenan-Induced Pain on lower limb muscle and ligament of rat. To evaluate pain mechanism in muscle and ligament, pain was induced by the injection of 2% $0.1m{\ell}$ carrageenan into the left lower limb muscle of rats after rats were anesthesized with 3% enflurane. Rats were killed on 72 hours after pain induction under the anesthesia. anterior rectus femoris muscle and its ligament were removed from rat hind limb. Morphological changes of them were peformed by the observation of light and electron microscopes. In the light microscopic findings, the muscle cells were polyheadral and situated with each other without small gap in control group. nucleus of cell was seen along the cell margin, and muscle cell groups were divided by regular narrow gap in cross section. In the pain-induced group, muscle cell groups were divided each other by the irregular gap, and some of groups formed larger than other cell groups by the fusion. Intercellular gap of most cell groups were increased compared with control groups. And also, perimysium of muscle cell groups was swollen in cross section. In control group, muscle cells contacted each other closely and each cell was divided by perimysium. The intracellular gaps were not seen between myofibrills, and also striations were well defined between muscle cells in longitudinal section. In pain-induced group, muscle cells were divided by the small intracellular gaps. And also, muscle cell showed many a short cross or longitudinal intercellular gaps in longitudinal section. In light microscopic findings of control group, tendon was composed with many tendon fibers contacted each other closely without gap. The free margin of tendon was fused, and apso the tendon fibers did not invaded between muscles. In pain-induced group, tendon was divided small groups by intertendinous gap, and also the margin of tendon divided by small groups. In the free margin, tendon invaded into muscle cells, and also fibroblasts between tendon fibers were long and lance-shaped. From these results, it is suggested that pain induction by carrageenan injured rat skeletal muscle and ligament by the morphological changes.

• 대한의용생체공학회:의공학회지
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• 제28권5호
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• pp.636-646
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• 2007

Adequate postural control depends on the spatial and temporal integration of vestibular, visual, and somatosensory information. Especially, the musculoskeletal function is essential to maintain the postural control. The experimental studies was performed on the muscular activities in the lower extremities during maintaining and moving exercises on an unstable platform with Magneto Rheological(MR) dampers. The unstable platform of the developed system was controlled by electric currents to the MR dampers. A subject executed the maintaining and moving exercises which are presented through the display monitor. The electromyographies of the eight muscles in lower extremities were recorded and analyzed in the time and the frequency domain: the muscles of interest were rectus femoris(RF), biceps femoris(BF), tensor fasciae latae(TFL), vastus lateralis(VL), vastus medialis(VM), gastrocnemius(Ga), tibialis anterior(TA), Soleus(So). The experimental results showed that the muscular activities differed in the four moving exercises and the nine maintaining exercises. For the anterior-posterior pattern, the TA showed highest activities; for the left-right pattern, the TFL; for the 45, $-45^{\circ}$ pattern, the TFL and TA. Also, the rate of the increase in the muscular activities were affected by the condition of the unstable platform with MR dampers for the maintaining and moving exercises. The experimental results suggest that the choice of different maintaining and moving exercises could selectively train different muscles in various intensity. Futhermore, the findings suggested that the training using this system can improve the ability of postural control.

• 한국운동역학회지
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• 제24권3호
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• pp.287-293
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• 2014

The purpose of this study was to investigate the effects of Hoehn-Yahr scale on the activation of lower-extremity muscles during walking. Electromyography (EMG) analysis was carried out on 36 patients with Parkinson's disease in the off phase of the medication cycle. We recorded EMG signals of the tibialis anterior (TA), medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus (SOL), rectus femoris (RF), vastus lateralis (VL), semitendinosus (ST) and biceps femoris (BF) using Noraxon 16 channels EMG system during walking at preferred speed. Rectified EMG signals were normalized to reference voluntary contractions (RVC) over a gait cycle at the preferred speed, allowing for an assessment of how the activity was distributed over the gait cycle. Compared to the H & Y Scale 1, H & Y Scale 3 exhibited greater activation of the vastus lateralis during mid-stance and greater activation of the medial gastrocnemius during terminal swing. Compared to the H & Y Scale 1, H & Y Scale 2 and 3 exhibited less activation of the tibialis anterior during initial swing. We conclude that the more Hoen & Yahr Scale increase, the more abnormal lower-extremity muscles activation.

• 한국운동역학회지
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• 제19권4호
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• pp.647-653
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• 2009

본 연구의 목적은 박스 드롭 착지 시 남자와 여자 발레 무용수들의 하지의 생체역학적 요인의 차이를 규명하는 것이다. 본 연구에 참가한 연구 대상자는 20~23세 사이의 여자발레무용수 9명과 21~24세 사이의 남자발레무용수 9명이었다. 박스 드롭 착지 동작은 양 발을 편안하게 벌린 상태에서 연구대상자의 무릎 높이의 박스 위에서 지면반력기 위에 뛰어 내리도록 하였다. 하지의 생체역학적 변인의 계산을 위해서 6대의 고해상도 비디오카메라와 2대의 지면반력기 그리고 8채널 무선 근전도 시스템을 사용하였다. 변인의 차이를 규명하기 위해서 성(2수준, 남자 발레 무용수 여자 발레 무용수)을 독립변인으로 하는 독립 t-test를 실시하였다. 연구결과, 여자발레무용수들은 남자발레 무용수들보다 박스 드롭 착지 시 최대무릎굴곡각도 변인에서 성의 차이가 나타났으나, 나머지 하지의 생체역학적 요인들에서는 성의 차이가 나타나지 않았다. 어린 나이에 점프와 착지 훈련과 교육을 받는 것은 잠재적인 전방십자인대 부상위험 요인을 감소시킨다.

• PNF and Movement
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• 제17권3호
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• pp.441-450
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• 2019

Purpose: This study identified the co-activation of quadriceps and hamstring muscles during hamstring strengthening exercises in healthy adults. Methods: Twenty-one participants were required for the present study design to achieve 80% power, 0.8 effect size (η2), and an alpha level of 0.05. Thus, this study recruited 21 healthy adults. All participants performed Nordic exercises, bridge exercises, and one-leg deadlifts randomly. The activity of the rectus femoris, vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), and semitendinosus (SM) were measured. In addition, the ratios of VM/VL and hamstring/quadriceps (HQ) were measured during the three hamstring strengthening exercises using electromyography. One-way ANOVA was used to compare the co-activation of quadriceps and hamstring muscles in the three exercises. Results: The activity of VM and VL during the performance of one-leg deadlifts was significantly higher than the other two exercises. The BF had significantly higher activity during the Nordic exercises compared to the other two exercises. In addition, the SM activation was significantly greater during Nordic exercises than one-leg deadlifts. Additionally, there was significant difference in HQ ratio among hamstring strengthening exercises. In specific, the one-leg deadlifts yielded a significantly lower HQ ratio. Conclusion: This study revealed that one-leg deadlifts are effective in rehabilitation for anterior cruciate ligament injury. In addition, Nordic exercises can be recommended to facilitate hamstring muscle activation.

• The Journal of Korean Physical Therapy
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• 제33권2호
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• pp.53-61
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• 2021

Purpose: This study examined the impacts of action observational physical training related to stair walking on the stair walking ability and self-efficacy of chronic stroke patients. Methods: This study was conducted on 24 chronic stroke patients, who were assigned randomly to an action observational physical training group (12 persons) and a landscape observation physical training group (12 persons). To the action-observational physical training group, five videos related to stair walking were presented, and after observing them, physical training was carried out. The landscape observation physical training group observed the videos consisting of landscape, where there were no humans and animals, and then underwent physical training. This study measured the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius to examine the muscle activity of the lower limb. A timed up and go and step test was performed to examine the balance ability, and a timed stair test was conducted to examine their stair walking ability. A self-efficacy scale was measured to examine the degree of their confidence of performing stair walking. The assessment was conducted three times in total: pre-, post-, and follow-up surveys. Results: As a result of this study, the action observational physical training group significant improvement after the intervention than in the landscape observation physical training group. Moreover, the follow-up study four weeks after the intervention showed significant improvements in the action observational physical training group (p<0.05). Conclusion: These results show that the action observational physical training had a positive impact on the stair walking ability and self-efficacy of chronic stroke patients.

• The Journal of Korean Physical Therapy
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• 제25권2호
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• pp.103-109
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• 2013

Purpose: This study was conducted in order to suggest an effective method of daily life movement training for stroke patients by comparison and analysis of the biomechanic characteristics of sitting up from a lying posture in stroke patients and healthy elderly participants. Methods: Fifteen stroke patients and 15 age-matched elderly participants were included in the study. The movement of sitting up from a lying posture was divided into three stages, and the differences in muscle activity in the sternocleidomastoid (SCM), rectus abdominis (RA), external oblique (EO), and rectus femoris (RF) during the movement were analyzed. Results: Subjects in the experimental group showed slower speed than those in the control group. In the neck joint, the change of angle in movement showed a larger decrease at all stages in the experimental group than in the control group; the movement also decreased in stages I and II in the upper trunk joint. The movement also showed a statistically significant decrease in stage II in the lower trunk, pelvic, and hip joints. The SCM showed higher activity in the control group than in the experimental group, showing a statistically significant difference; the RA showed high activity in the experimental group. The RF showed higher activity in the control group than in the experimental group, showing a statistically significant difference. Conclusion: From the results obtained above, increasing movements in the neck, pelvic, and hip joints and strengthening of lower body muscles are required in order to improve the ability for getting up from a lying posture in stroke patients.