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한국운동역학회> 한국운동역학회지> Calculation and Comparison of Maximum Lyapunov Exponent in Different Direction: An Approach to human Gait Stability

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Calculation and Comparison of Maximum Lyapunov Exponent in Different Direction: An Approach to human Gait Stability

Paudel Dinesh
  • : 한국운동역학회
  • : 한국운동역학회지 31권1호
  • : 연속간행물
  • : 2021년 03월
  • : 24-29(6pages)
한국운동역학회지

DOI


목차

INTRODUCTION
METHODS
RESULTS
DISCUSSION
CONCLUSION
LIMITATION
REFERENCES

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초록 보기

Objective: The goal of this study is to calculate and compare the Maximum Lyapunov Exponent (MLE) for the anteroposterior, mediolateral and vertical displacement of the markers attached to bony land marks of the trunk and foot.
Method: Ten young and healthy male subjects (age: 26.5±3.27 years, height: 167.44±5.12 cm, and weight 69.5±7.36) participated in the study. Three-dimensional positional coordinate of eight different trunk and foot marker during walking on tread mill were analysed.
Results: MLE values for anteroposterior displacement of the marker were found to be significantly different with MLE values for mediolateral and vertical displacement whereas MLE values for mediolateral displacement of the marker shows no significant difference with the MLE values for vertical displacement of the markers at significance level 0.05.
Conclusion: Finding of this study suggest that it is essential to consider the displacement in all three direction to examine the real characteristic of a gait signal.

UCI(KEPA)

I410-ECN-0102-2022-600-000585946

간행물정보

  • : 예체능분야  > 체육학
  • : KCI등재
  • :
  • : 계간
  • : 1226-2226
  • : 2093-9752
  • : 학술지
  • : 연속간행물
  • : 1992-2022
  • : 1225


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32권1호(2022년 03월) 수록논문
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1머신러닝 기반 골프 퍼팅 방향 예측 모델을 활용한 중요 변수 분석 방법론

저자 : Yeon Ho Kim , Seung Hyun Cho , Hae Ryun Jung , Ki Kwang Lee

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 32권 1호 발행 연도 : 2022 페이지 : pp. 1-8 (8 pages)

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Objective: This study proposes a methodology to analyze important variables that have a significant impact on the putting direction prediction using a machine learning-based putting direction prediction model trained with IMU sensor data.
Method: Putting data were collected using an IMU sensor measuring 12 variables from 6 adult males in their 20s at K University who had no golf experience. The data was preprocessed so that it could be applied to machine learning, and a model was built using five machine learning algorithms. Finally, by comparing the performance of the built models, the model with the highest performance was selected as the proposed model, and then 12 variables of the IMU sensor were applied one by one to analyze important variables affecting the learning performance.
Results: As a result of comparing the performance of five machine learning algorithms (K-NN, Naive Bayes, Decision Tree, Random Forest, and Light GBM), the prediction accuracy of the Light GBM-based prediction model was higher than that of other algorithms. Using the Light GBM algorithm, which had excellent performance, an experiment was performed to rank the importance of variables that affect the direction prediction of the model.
Conclusion: Among the five machine learning algorithms, the algorithm that best predicts the putting direction was the Light GBM algorithm. When the model predicted the putting direction, the variable that had the greatest influence was the left-right inclination (Roll).

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2전방 점프 착지 시 만성 발목 불안정성이 자세 조절에 미치는 영향

저자 : Kew-wan Kim , Kyoungkyu Jeon , Seokwoo Park , Seji Ahn

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 32권 1호 발행 연도 : 2022 페이지 : pp. 9-16 (8 pages)

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Objective: The purpose of this study was to investigate how the chronic ankle instability affects postural control during forward jump landing.
Method: 20 women with chronic ankle instability (age: 21.7 ± 1.6 yrs, height: 162.1 ± 3.7 cm, weight: 52.2 ± 5.8 kg) and 20 healthy adult women (age: 21.8 ± 1.6 yrs, height: 161.9 ± 4.4 cm, weight: 52.9 ± 7.2 kg) participated in this study. For the forward jump participants were instructed to stand on two legs at a distance of 40% of their body height from the center of force plate. Participants were jump forward over a 15 cm hurdle to the force plate and land on their non-dominant or affected leg. Kinetic and kinematic data were obtained using 8 motion capture cameras and 1 force plates and joint angle, vertical ground reaction force and center of pressure. All statistical analyses were using SPSS 25.0 program. The differences in variables between the two groups were compared through an independent sample t-test, and the significance level was to p < .05.
Results: In the hip and knee joint angle, the CAI group showed a smaller flexion angle than the control group, and the knee joint valgus angle was significantly larger. In the case of ankle joint, the CAI group showed a large inversion angle at all events. In the kinetic variables, the vGRF was significantly greater in the CAI group than control group at IC and mGRF. In COP Y, the CAI group showed a lateral shifted center of pressure.
Conclusion: Our results indicated that chronic ankle instability decreases the flexion angle of the hip and knee joint, increases the valgus angle of the knee joint, and increases the inversion angle of the ankle joint during landing. In addition, an increase in the maximum vertical ground reaction force and a lateral shifted center of pressure were observed. This suggests that chronic ankle instability increases the risk of noncontact knee injury as well as the risk of lateral ankle sprain during forward jump landing.

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3오르막보행 시 타이거스텝 하지 움직임에 미치는 영향

저자 : Jihyuk Kang , Sukhoon Yoon

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 32권 1호 발행 연도 : 2022 페이지 : pp. 17-23 (7 pages)

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Objective: The aim of this study was to investigate the effect Tiger-step walking on the movement of the lower extremities during walking.
Method: Twenty healthy male adults who had no experience of musculoskeletal injuries on lower extremities in the last six months (age: 26.85 ± 3.28 yrs, height: 174.6 ± 3.72 cm, weight: 73.65 ± 7.48 kg) participated in this study. In this study, 7-segments whole-body model (pelvis, both side of thigh, shank and foot) was used and 29 reflective markers and cluster were attached to the body to identify the segments during the gait. A 3-dimensional motion analysis with 8 infrared cameras and 7 channeled EMG was performed to find the effect of tigerstep on uphill walking. To verify the tigerstep effect, a one-way ANOVA with a repeated measure was used and the statistical significance level was set at α=.05.
Results: Firstly, Both Tiger-steps showed a significant increase in stance time and stride length compared with normal walking (p<.05), while both Tiger-steps shown significantly reduced cadence compared to normal walking (p<.05). Secondly, both Tiger-steps revealed significantly increased in hip and ankle joint range of motion compared with normal walking at all planes (p<.05). On the other hand, both Tiger-steps showed significantly increased knee joint range of motion compared with normal walking at the frontal and transverse planes (p<.05). Lastly, Gluteus maximus, biceps femoris, medial gastrocnemius, tibialis anterior of both tiger-step revealed significantly increased muscle activation compared with normal walking in gait cycle and stance phase (p<.05). On the other hand, in swing phase, the muscle activity of the vastus medialis, biceps femoris, tibialis anterior of both tiger-step significantly increased compared with those of normal walking (p <.05).
Conclusion: As a result of this study, Tiger step revealed increased in 3d range of motion of lower extremity joints as well as the muscle activities associated with range of motion. These findings were evaluated as an increase in stride length, which is essential for efficient walking. Therefore, the finding of this study prove the effectiveness of the tiger step when walking uphill, and it is thought that it will help develop a more efficient tiger step in the future, which has not been scientifically proven.

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4평균대 한발 몸 펴 옆 공중돌기의 성패에 따른 운동학적 요인 분석

저자 : Choong Min Jung , Sang-kyoon Park

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 32권 1호 발행 연도 : 2022 페이지 : pp. 24-30 (7 pages)

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Objective: The purpose of this study was to determine the factors of successful and unsuccessful movements through the analysis of kinematics and muscle activity of the Free Aerial Cartwheel on the balance beam.
Method: Subjects (Age: 22.8 ± 2.4 yrs., Height: 158.7 ± 5.0 cm, Body mass: 54.1 ± 6.4 kg, Career: 13 ± 2.4 yrs.) who were currently active as female gymnasts participated in the study. They had no history of surgical treatment within 3 months. Subject criteria included more than 10 years of professional experience in college and professional level of gymnastics and the ability to conduct the Free Aerial Cartwheel on the Balance Beam. Each subject performed 10 times of Free Aerial Cartwheel on the balance beam. One successful trial and one unsuccessful trial (failure) among 10 trials were selected for the comparison.
Results: It was found that longer time required in case of unsuccessful trial when performing the Free Aerial Cartwheel on the balance beam compared with successful trial. It is expected to be the result of movement in the last landing section (i.e. phase 5). In addition, it was found that the center of gravity of the body descends at a high speed to perform the jump (i.e. phase 2) in order to obtain a sufficient jumping height when the movement is successful while the knee joint is rapidly extended to perform a jump when movement fails. In the single landing section after the jump (i.e. phase 4), if the ankle joint rapidly dorsiflexed after take-off and the hip joint rapidly flexed, so landing was not successful. Conversely, in a successful landing movement, muscle activity of the biceps femoris was greatly activated resulting no shaking in the last landing section (i.e. phase 5).
Conclusion: In order to succeed in this movement, it is necessary to perform a strong jump after rapidly descending the center of gravity of the body using the force of the biceps femoris muscle. Further improvement of the skills on the balance beam requires the analysis of the game-like situation with continuous research on kinematic and kinematic analysis of various techniques, jumps, turns, etc.

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5TRX 스트랩 길이에 따른 체간 근육의 활성도 비교

저자 : Yeon Kyung Hong , Sukhoon Yoon

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 32권 1호 발행 연도 : 2022 페이지 : pp. 31-36 (6 pages)

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Objective: The purpose of this study was to investigate muscle activation according to the four strap lengths in the TRX plank exercise to provide scientific and accurate data on effective training methods.
Method: Twenty healthy men who had at least 6 months of weight training experience and could fully adjusted plank exercise, were participate in this study (age: 25.2 ± 3.7 yrs., height: 174.2 ± 3.9 cm., weight: 71.2 ± 9 kg). To pursue the study purpose, surface electrodes were attached to trunk muscles (pectoralis major, rectus abdominis, external oblique, internal oblique, erector spinae, latissimus dorsi) and lower extramity muscles (gluteus maximus, rectus femoris, gastrocnemius), and the muscle activity was measured using 11-channel electromyography equipment. In order to verify the muscle activation according to the four strap lengths during TRX plank exercise, an one-way ANOVA with repeated measure was used with statistical significance level set at as α=.05.
Results: First, there were statistically significant differences in pectoralis major, rectus abdominis, external oblique, internal oblique, and erector spinae among TRX strap lengths. Second, there were statistically significant differences in gluteus maximus, rectus femoris, and gastrocnemius among TRX strap lengths. Third, even though no statistically significant difference found in latissimus dorsi, but increased muscle activation tendency was showed as the length of the strap increased.
Conclusion: From the results of this study, it may be possible that TRX exercise prevent injuries and improve lower extremity muscle as well as trunk muscles by setting appropriate length of strap.

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1외측 발목 염좌 병력에 따른 정적 하지 정렬 차이: 외측 발목 염좌의 예측인자로서 정적 하지 정렬 검사의 효용성과 한계점

저자 : Hyung Gyu Jeon , Sunghe Ha , Inje Lee , Tae Kyu Kang , Eun Sung Kim , Sae Yong Lee

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 1-15 (15 pages)

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Objective: The aim of this study was to investigate 1) the difference in static lower extremity alignment (SLEA) according to a history of lateral ankle sprain (LAS), 2) to identify SLEA factors affecting LAS, and 3) to present the cut-off value and 4) the usefulness and limitations of the SLEA measurement.
Method: This case-control study recruited 88 men (age: 27.78±4.69 yrs) and 39 women (age: 24.62±4.20 yrs) subjects with and without LAS. SLEA measurement protocol included Q angle, tibiofemoral angle, genu recurvatum, rear foot (RF) angle, tibal varum and torsion, navicular drop, ankle dorsiflexion range of motion (DF ROM). Independent t-test, logistic regression and receiver operating characteristic (ROC) curve were used for statistical analysis.
Results: Men with a history of LAS had significantly smaller Q angles both in standing and in supine position, while women with a history of LAS had significantly greater DF ROM in non-weight bearing (NWB; p < 0.05). Logistic regression model suggests tibial varum (OR = 0.779, p = 0.021) and WB DF ROM (OR = 1.067, p = 0.045) were associated with LAS in men. In case of women, there were no significant SLEA factors for LAS, however, ROC curve analysis revealed standing RF angle (AUC = 0.647, p = 0.028) and NWB DF ROM (AUC = 0.648, p = 0.026) could be affecting factors for LAS.
Conclusion: There are differences in SLEA according to the history of LAS, furthermore, the identified items were different by sex. In case of men, tibial varum and WB DF ROM affect LAS occurrence. Standing RF angle and NWB DF ROM of women could be a predictor for LAS. However, since the sensitivity and specificity in most of the SLEA measurements are low, kinematic in dynamic tasks should be considered together for a more accurate evaluation of LAS risk.

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2요통 유무에 따른 달리기 시 충격과 충격 흡수율

저자 : Young-seong Lee , Sihyun Ryu , Ho Jong Gil , Sang-kyoon Park

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 16-23 (8 pages)

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Objective: The purpose of the study was to compare the acceleration and shock attenuation (SA) of the runners with/without low back pain (LBG vs. NLBG) while running at 2.5 m/s, 3.0 m/s, 3.5 m/s and 4.0 m/s.
Method: 15 adults without low back pain (age: 23.13±3.46 years, body weight: 70.13±8.94 kg, height: 176.79 ±3.68 cm, NLBG) and 7 adults with low back pain (age: 27.14±5.81 years, body weight: 73.10±10.74 kg, height: 176.41±3.13 cm, LBG) participated in this study. LBG was recruited through the VAS pain rating scale. All participants ran on an instrumented treadmill (Bertec, USA).
Results: The LBG shows statistically greater vertical acceleration at the distal tibia during running at 3.5 m/s and 4.0 m/s and greater shock attenuation from the distal tibia to the head during running at 3.5 m/s compared with the NLBG during running (p<.05). As the speed increased, there was a statistically significant increase in vertical/resultant acceleration and shock attenuation for both groups.
Conclusion: The findings indicated that the runners with low back pain (LBG) experience greater impact and shock attenuation compared with non-low back pain group (NLBG) during fast running. However, it is still inconclusive whether high impact on the lower extremity during running is the main cause of low back pain in the population. Thus, it is suggested that the study on low back pain should observe the characteristics of impact during running with individuals' low back pain experience and clinical symptoms.

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3Calculation and Comparison of Maximum Lyapunov Exponent in Different Direction: An Approach to human Gait Stability

저자 : Paudel Dinesh

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 24-29 (6 pages)

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Objective: The goal of this study is to calculate and compare the Maximum Lyapunov Exponent (MLE) for the anteroposterior, mediolateral and vertical displacement of the markers attached to bony land marks of the trunk and foot.
Method: Ten young and healthy male subjects (age: 26.5±3.27 years, height: 167.44±5.12 cm, and weight 69.5±7.36) participated in the study. Three-dimensional positional coordinate of eight different trunk and foot marker during walking on tread mill were analysed.
Results: MLE values for anteroposterior displacement of the marker were found to be significantly different with MLE values for mediolateral and vertical displacement whereas MLE values for mediolateral displacement of the marker shows no significant difference with the MLE values for vertical displacement of the markers at significance level 0.05.
Conclusion: Finding of this study suggest that it is essential to consider the displacement in all three direction to examine the real characteristic of a gait signal.

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4보행 시 여성 노인의 하지 관절 근력과 국부 동적 안정성과의 관계

저자 : Jiseon Ryu

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 30-36 (7 pages)

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Objective: The objective of the present study was to analyze the relationship between strength of the lower extremity's joints and their local dynamic stability (LDS) of gait in elderly women.
Method: Forty-five elderly women participated in this study. Average age, height, mass, and preference walking speed were 73.5±3.7 years, 153.8±4.8 cm, 56.7±6.4 kg, and 1.2±0.1 m/s, respectively. They were tested torque peak of the knee and ankle joints with a Human Norm and while they were walking on a treadmill at their preference speed for a long while, kinematic data were obtained using six 3-D motion capture cameras. LDS of the lower extremity's joints were calculated in maximum Lyapunov Exponent (LyE). Correlation coefficients between torque of the joints and LyE were obtained using Spearman rank. Level of significance was set at p<.05.
Results: Knee flexion torque and its LDS was negatively associated with adduction-abduction and flexionextension movement (p<.05). In addition, ratio of the knee flexion torque to extension and LDS was negatively related to internal-external rotation.
Conclusion: In conclusion, knee flexion strength should preferentially be strengthened to increase LDS of the lower extremity's joints for preventing from small perturbations during walking in elderly women.

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5모바일폰 문자 메시지가 동적 · 정적 보행자 충돌회피전략에 미치는 영향

저자 : Yeon-jong Lee , Joo-nyeon Kim

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Objective: The purpose of this study was to investigate the effect of mobile phone text messaging on the collision avoidance strategy for an approaching and stationary pedestrian.
Method: Eighteen healthy young adults participated in this study. Each participant was asked to perform a task to walking with/without mobile phone text messaging and a task to avoid collisions with another pedestrian who was approaching or stationary during walking.
Results: When text messaging with avoidance collision, it showed an early onset time, a larger mediolateral COM trajectory, trunk rotation angle and trunk rotation velocity (p<.05). Also, compared to an approaching pedestrian, when avoiding collision with a stationary pedestrian, it showed a later onset time, a lager avoidance displacement, mediolateral COM trajectory, trunk rotation angle (p<.05).
Conclusion: Results suggest that mobile phone text messaging while collision avoidance leads to delay the perception stage and alters the adaptation stage. Consequently, pedestrian executed in an exaggerated avoidance action to create a greater safety margin when attending to mobile phone test messages while avoiding another pedestrian.

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6골프 퍼팅 시 지면 경사도에 따른 운동학적 변인 분석

저자 : Jun-sung Park , Sung-hoon Shin , Young-tae Lim

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 44-49 (6 pages)

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Objective: The purpose of this study was to analyze kinematic variables according to ground slope angle during golf putting.
Method: 26 collegiate golfers (age: 22.54±2.15 kg, height: 174.64±6.07 cm, weight: 71.35±9.27 kg, handicap: 5.11±4.50) were participated, and 8 motion capture cameras (250 Hz), Nexus, and Kwon3DXP software were used to collect data. It was performed repeated measures ANOVA and Bonferroni adjustment. Alpha set at .05.
Results: Body alignments were not significantly different at address. Putter head trajectory and loft angle were significantly different, and AP direction of acceleration of putter head was significantly different. However, ML and SI direction of acceleration of putter head were not significantly different.
Conclusion: Therefore, it was identified that ground slope angle was affected the kinematic variables during putting, and it will be performed that correlation analysis between putting success rate and kinematic variables according to ground slope angle during golf putting.

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7모래주머니를 이용한 팔목과 몸통의 무게 증가가 만성 뇌졸중 환자들의 보행에 미치는 영향

저자 : Sangheon Park , Hee Sung Lim , Sukhoon Yoon

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 50-58 (9 pages)

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Objective: This study aimed to determine the effect of wrist and trunk weight loading using sandbags in stroke patients in order to provide the quantitative data for enhancement of gait movement.
Method: Twelve stroke patients, who have been diagnosed with hemiplegia over a year ago, were participated in this study. All subjects were asked to perform normal walking [N], wrist sandbag walking [W], wrist & trunk sandbag walking [WT], and both wrist sandbag walking [B] and both wrist & trunk sandbag walking [BT], respectively. Eight infrared cameras were used to collect the raw data. Gait parameters, arm swing, shoulder-pelvic kinematics, and lower extremity joint angle were calculated to examine the differences during walking.
Results: As a result, there were no significant differences in the gait parameters, shoulder-pelvis, and lower extremities joint angles, but significant differences were found in the range of motion and the anteversion in arm swing.
Conclusion: Wrist and trunk weight loading using sandbags affected the movement of the upper extremities only while it did not affect the movement of the lower extremities. It implies that it can reduce the risk of falling caused by a sudden movement change in lower extremities. In addition, the wrist and trunk weight loading using sandbags can induce changes in movement of the upper extremities independently and contribute to functional rehabilitation through resistance training.

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8전신진동운동, 보행 및 런닝과의 근육활성량 및 근 발현 특성 비교 분석을 통한 전신진동운동 효과검증

저자 : Young Jin Moon , Won Jun Cho

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 59-63 (5 pages)

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Objective: Through comparative analysis of muscle activity for whole-body vibration, walking and running movements, it is to verify the training effect of whole-body vibration exercise in terms of amount of exercise and muscle activity characteristics.
Method: Flat ground walking and slope walking (10 degrees) at a speed of 5 km/h, flat ground running and slope running (10 degrees) at a speed of 11 km/h for running were performed on treadmill, and squats were maintained at 12 Hz, 20 Hz, and 29 Hz conditions on Whole body vibration exercise equipment (Galileo). Muscle activity was analyzed through EMG analysis device for one minute for each condition.
Results: The Anterior Tibialis and Erector Spinae show greater exercise effect in whole-body vibration than walking and running. The Rectus Femoris, Biceps Femoris, and Gluteus Maximus have the best effect of exercise in flat running. Whole-body vibration exercise showed greater muscle activation effect as the frequency increased, and exercise effect similar to walking during the same exercise time.
onclusion: The amount of exercise through Whole-body vibration exercise was similar to that of walking exercise, and the Anterior Tibialis and Erector Spinae shows better exercise effect than walking and running.

KCI등재

9슬개대퇴동통증후가 성인 여성의 드롭랜딩 시 하지 주요관절의 운동역학적 변화에 미치는 영향

저자 : Kyoungkyu Jeon , Seunghyeok Yeom

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 64-71 (8 pages)

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Objective: This study investigated the different in isokinetic peak strength of the knee joint, and kinetics and kinematics in drop landing pattern of lower limb between the patellofemoral pain syndrome (PFPS) patients and normal.
Method: 30 adult females were divided into the PFPS (age: 23.13±2.77 yrs; height: 160.97±3.79 cm, weight: 51.19±4.86 kg) and normal group (age: 22.80±2.54 yrs, height: 164.40±5.77 cm, weight: 56.14±8.16 kg), with 15 subjects in each group. To examine the knee isokinetic peak strength, kinematics and kinetics in peak vertical ground reaction force during drop landing.
Results: The knee peak torque (Nm) and relative strength (%) were significantly weaker PFPS group than normal group. In addition, PFPS group had significantly greater hip flexion angle (°) than normal group. Moreover, normal group had significantly greater moment of hip abduction, hip internal rotation, and left ankle eversion than PFPS group, and PFPS group had significantly greater moment of knee internal rotation. Finally, there was significant differences between the groups at anteroposterior center of pressure.
Conclusion: The PFPS patients had weakened knee strength, and which can result in an unstable landing pattern and cause of more stress in the knee joints despite to effort of reduce vertical ground reaction force.

KCI등재

10지면에서의 마운틴 클라이밍 운동 시 상체의 위치 변화가 운동 강도와 근활성도에 미치는 영향

저자 : Jun-ho Park , Jae-hu Jung , Jong-geun Kim , Woen-sik Chae

발행기관 : 한국운동역학회 간행물 : 한국운동역학회지 31권 1호 발행 연도 : 2021 페이지 : pp. 72-78 (7 pages)

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Objective: The purpose of this study was to investigate relations and effectiveness about mountain climbling exercise with different level of support surfaces by analyzing heart rate and EMG data. A total of 10 male college students with no musculoskeltal disorder were recruited for this study.
Method: The biomechanical analysis was performed using heart rate monitor (Polar V800, Polar Electro Oy, Finland), step-box, exercise mat, and EMG device (QEMG8, Laxtha Inc. Korea, sampling frequency = 1,024 Hz, gain = 1,000, input impedance > 1012 Ω, CMRR > 100 dB). In this research, step-box were used to create different surface levels on the upper body (flat surface, 10% of subject's height, 20% of subject's height, and 30% of subject's hight). Based on these different conditions, data was collected by performing mountain climbing exercise during 30 seconds. Subjects were given 5 minutes of break to prevent muscular fatigue after each exercise. For each dependent variable, a one-way analysis of variance with repeated measures was conducted to find significant differences and Bonferroni post-hoc test was performed.
Results: The results of this study showed that exercise intensity was reduced statistically as increased surface level on the upper body. Muscle activity of the upper rectus abdominis and biceps femoris for 30% of surface level was significantly higher than the corresponding values for flat surface. However, the opposite was found in the rectus femoris. In general, muscle activity of the lower rectus abdominis, erector spinae, external oblique abdominis, and gluteus maximus increased when surface level increased, but the differences were not significant.
Conclusion: As a result, the increase in surface level of the body would change muscle activity of the upper body, indicating that different surface level of the upper body may cause significant effect on particular muscles to be more active during mountain climbing exercise. Based on results of this study, it is suggested to set up an appropriate surface level to target particular muscle to expect an effective training. It is also important to set adequate surface levels to create an effective training condition for preventing exercise injuries.

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