• Physical Therapy Rehabilitation Science
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• 제9권1호
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• pp.18-24
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• 2020

Objective: The purpose of this study was to compare the activities of the abdominal muscles according to trunk stabilization exercises using Swiss ball in normal individuals. Design: Cross-sectional study. Methods: Ten healthy university students participated in this study. The subjects were required to complete the following three exercise positions: Exercise position 1, sitting on a Swiss ball and lifting the legs; Exercise position 2, pushing to a plank position from an ending position; and Exercise position 3, push-up posture with the legs on a Swiss ball. Changes in the trunk muscle activities were estimated using Biometric electromyography (EMG). Activities of the dominant side internal oblique muscle (IOM) and external oblique muscle (EOM) were estimated in all participants. The maximal voluntary isometric contraction (MVIC %) was measured to standardize the EMG signals for the IOM and EOM during maximum resistance when sitting up with each shoulder pointing towards the contralateral pelvis with knees bent and both arms crossed on the chest for 5 seconds. Results: There was a significant difference in the activity of the internal and external oblique muscles between Exercises 1 and 2 and Exercises 1 and 3 (p<0.05). Furthermore, the IOM/EOM activity ratio was the greatest during Exercise 3 and the smallest during Exercise 1. IOM and EOM activities were the greatest during Exercise 2 with greater EOM activity. Conclusions: In future studies, it will be necessary to investigate muscle activities by supplementing the above-mentioned limitations during the stabilization exercise. The results of this study may be used as a basis for controlling the intensity and frequency of exercise while prescribing trunk stabilization exercises.

• 한국운동역학회지
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• 제17권3호
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• pp.147-154
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• 2007

This study's purpose is to investigate the effects on leg muscle activity caused by perturbation, using a trapdoor system during the support phase of gait for healthy adults (n = 6, height $177.5{\pm}5.5cm$, weight $81.0{\pm}9.5kg$, age $30.0{\pm}3.3yrs$). The trapdoor had the functional ability of causing inversion or eversion. The release time for the trapdoor was specified for two times, 0.3 and 0.5 seconds after heel contact. While altering these variables, EMG was recorded for the leg muscles (rectus femoris, biceps femoris, vastus lateralis, tibialis anterior, gastrocnemius, soleus). The following conclusions were derived. The steptime was longer for the 0.5s eversion than 0.3s inversion condition. So in order to regain stability after the perturbation the unsupporting leg reached forward rapidly. This quick reflex can be observed through the center of pressure (COP) and its rapid change in direction. The gastrocnemius was activated throughout the total experiment. There was a low amount of activity recorded in the rectus femoris, vastus lateralis and tibialis anterior except for the condition of inversion 0.3s. For most of the conditions, the highest average EMG peak values were recorded during the condition of inversion 0.3s. The iEMG patterns were similar for the conditions of inversion 0.3s and eversion 0.3s. To cope with the rapid change in these conditions, the biceps femoris was activated. During the experiment except for the condition of normal gait, the activity of the soleus and gastrocnemius was relatively high. Therefore, to prevent injury from perturbation of the lower leg strengthening of the soleus and gastrocnemius is required. Likewise to prevent injury to the thigh strengthening for the biceps femoris.

• 한국운동역학회지
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• 제17권3호
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• pp.1-10
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• 2007

The purpose of this study was to examine the differences of lower limbs muscle activities depending on three walking speeds of 2.5km/h, 5.0km/h and 7.5km/h during forward walking and backward walking making 14 students the subjects of this study. To achieve this aim, surface electrodes for factor analysis of EMG were adhered to rectus femoris, biceps femoris, tibialis anterior and gastrocnemius medial head of right lower limbs. The conclusions through this study are as follows. 1) The muscle activity of rectus femoris was higher in backward walking group than in forward walking group and it was the highest at 7.5km/h walking speed. 2) The muscle activity of biceps femoris was higher in forward walking group than in backward walking group. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed. 3) The muscle activity of tibialis anterior was higher in backward walking group than in forward walking group. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed. 4) The muscle activity of gastrocnemius medial head was higher in backward walking group than in forward walking group except P2. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed.

• 농촌계획
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• 제28권2호
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• pp.33-40
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• 2022

The purpose of this study is to review the effect of previous research data with virtual reality-based Physical Activity Therapy Programs(PATPs) in adult on the physical fitness factors. Research articles were retrieved from 2008 to 2021 with the Research Information Sharing Service(RISS) and Pubmed database. The main search terms were 'care', 'therapy', 'healing', 'exercise' or 'physical activity', and 'virtual reality'. The criteria for selecting articles of this study were the originality, duplication, Randomized controlled trial(RCT) experiment and subject. Finally, 18 papers were selected among 318 articles, which were excluded if any of the criteria was not satisfied. Most of papers(15) were conducted in the last 5 years, because of the high interest due to the development of virtual reality implementation technology and COVID-19 pandemic. The participants were mainly patients(8), and the types of diseases were stroke(2). The physical fitness factors were mostly balance ability(7), muscle strength(7), and range of motion(6). All the physical fitness factors were significantly improved after PATPs. However, 11 studies were conducted for less than 4 weeks, including 6 studies were performed a bout of acute exercise. Also, 14 studies did not clearly present the intensity of PATPs. In addition, there were 9 studies, that simply applied games without specialized programs. In conclusion, it seems that virtual reality-based PATPs have a positive effect on physical fitness factors. However, VR-based PATPs should be specialized and developed in order to verify their effectiveness for the further research.

• 한국항해학회지
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• 제20권3호
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• pp.137-162
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• 1996

Today diving activity and technology are indispensable for underwater technology and offshore engineering. And then diving business is still more important to business of subsea. This study surveyed the issue of diving activity in Korea as for compared foreign diving activity. This paper analyzed the status of diving business that include commercial and sport-leisure diving business and development of commercial divers in Korea. This paper reputed the object, the necessity and the character of commercial divers. For the purpose of this study is considered in order to analyze the environment of commercial divers and propose the planning for industrial diving business. Under the present circumstance in Korea this development planning study may be restricted. but the effective planning to activate Korean commercial diving business is abstracted as follows; First, establishment of new course, grade, certificate and licence test for diver is a pre-requisite factor for the successful enactment. Second, the political assistance of concerned government authority is needed. Third, establishment of Korean diving school and medical center for divers are strongly required. Forth, setting up the department of diving activity in university.

• 한국운동역학회지
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• 제29권2호
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• pp.105-112
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• 2019

Objective: The main purpose of this study was to investigate the effects of wearing an ankle weight belt while performing gait in water by focusing on the effect of using ankle weights have on the gait kinematics and the muscle activities for developing optimum training strategies. Method: A total of 10 healthy male university students were recruited for the study. Each participant was instructed to perform 3 gait conditions; normal walking over ground, walking in water chest height, and walking in water chest height while using ankle weights. All walking conditions were set at control speed of $4km/h{\pm}0.05km/h$. The depth of the swimming pool was at 1.3 m, approximately chest height. The motion capture data was recorded using 6 digital cameras and the EMG was recorded using waterproof Mini Wave. From the motion capture data, the following variables were calculated for analysis; double and single support phase (s), swing phase (s), step length (%height), step rate (m/s), ankle, knee, and hip joint angles ($^{\circ}$). From the electromyography the %RVC of the lower limb muscles medial gastrocnemius, rectus femoris, erector spinae, semitendinosus, tibialis anterior, vastus lateralis oblique was calculated. Results: The results show significant differences between the gait time, and step length between the right and left leg. Additionally, the joint angular velocities and gait velocity were significantly affected by the water resistance. As expected, the use of the ankle weights increased all of the lower leg maximum muscle activities except for the lower back muscle. Conclusion: In conclusion, the ankle weights can be shown to stimulate more muscle activity during walking in chest height water and therefore, may be useful for rehabilitation purposes.

• 한국운동역학회지
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• 제31권2호
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• pp.140-147
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• 2021

Objective: The purpose of this study is to identify the mechanism of changes in maximum voluntary torque with the magnitude and duration of pre-activation torque during voluntary isometric knee extension. Method: 11 male subjects (age: 25.91±2.43 yrs., height: 173.12±3.51 cm, weight: 76.45±7.74 kg) participated in this study. The subjects were required to produce maximal voluntary isometric torque with a particular pre-activation torque condition. The properties of pre-activation torque consisted of the combinations of 1) three levels of magnitude, e.g., 32 Nm, 64 Nm, 96 Nm, and 2) two levels of duration, e.g., 1 sec, and 3 sec; thus, a total of six conditions were given to the subjects. The force and EMG data were measured using the force transducers and wireless EMG sensor, respectively. Results: The results showed that the maximum voluntary torque increased the most with relatively large and fast (96 Nm, 1 sec) pre-activation condition. Similarly, with relatively large and fast (96 Nm, 1 sec) preactivation, it was found that the integrated EMG (iEMG) of the agonist muscles increased, while no significant changes in the co-contraction of the antagonist muscles for the knee extension. Also, the effect of pre-activation conditions on the rate of torque development was not statistically significant. Conclusion: The current findings suggest that relatively larger in magnitude and shorter in duration as the properties of pre-activation lead to a larger magnitude of maximal voluntary torque, possibly due to the increased activity of the agonist muscles during knee extension.

• 한국운동역학회지
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• 제32권2호
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• pp.43-48
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• 2022

Objective: The purpose of this study was to verify the effectiveness among simulating ski jumping trainings by comparing with actual ski jump. Method: Three healthy youth national athletes were recruited for this study (age: 13.70 ± 0.9 yrs, height: 169.30 ± 0.9 cm, jumping caree: 5.3 ± 0.9 yrs). Participants were asked to performed ski jumping with 3 simulating and one actual situation. A 3-dimensional motion analysis with 5 channels of EMG was performed in this study. Muscle activations of Rectus Femoris [RF], Tibialis Anterior [TA], Thoracis [TH], Gluteus maximus [GM], and Gastronemius [GL] were achieved with sampling rate of 2,000 Hz during each jump. Results: In the case of S1 in the actual jumping motion, the deviation of the muscle activity peak did not appear each trial, and the jump timing was consistent. For S2, the timing of the muscles peak activation which can maintain the posture of the upper body and ankles appeared at the beginning. In the case of S3, the part maintaining the ankle posture at the beginning appeared, but it could be expected that it would progress in the vertical direction due to the activation of GL at the time of jumping. Conclusion: The muscle activation peak before the take-off point showed a different pattern for each athlete, and individual differences were large. In addition, it was attempted to confirm the actual jump with simulation jump, and it was found that not only the difference in patterns but also the fluctuations in the timing of each muscle activation peak were large.

• 한국운동역학회지
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• 제32권2호
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• pp.49-55
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• 2022

Objective: This study aims to verify the front squat motions using by two different surfaces, thereby elucidating the grounds for effective training environment that can minimize the risk of injury. Method: Total of 10 healthy male crossfit athletes were recruited for this study (age: 32.30 ± 3.05 yrs., height: 173.70 ± 5.12 cm, body mass: 82.40 ± 6.31 kg, 1RM: 160 ± 13.80 kg). All participants are those who know how to do front squats well with more than five years of crossfit athlete experience. All participants have sufficient experience in front squats on two types of surface which are soft surface (SS) and hard surface (HS). In each surface, participant perform 10reps of the front squat with 80% of the pre-measured 1RM. A 3-dimensional motion analysis with 8 infrared cameras and 2 channels of EMG was performed in this study. Paired sample t-test was used for statistical verification between two surfaces. The significant level was set at α=.05. Results: The significantly decreased rectus femoris muscle activation was found in SS compared with that of HS on phase 1 (p<.05). Also, ROM of ankle joint was significantly increased in the SS compare with that of HS on phase 1 (p<.05). The muscle activity ratio of gluteus maximus/rectus femoris showed a significant difference only in SS compared with that of HS on phase 1 (p<.05). Conclusion: In conclusion, Korean crossfit boxes should consider the use of hard surface, which has a relatively less risk of injury than soft surface, in selecting flooring materials. For the Crossfit athletes, they are also considered appropriate to train on a relatively hard surface.

• 농촌계획
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• 제28권1호
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• pp.81-87
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• 2022

This study analyzed the awareness and demand of participants in a physical activity therapy program(PATP) of a social welfare-type cultural regeneration space in urban and rural areas. As a result of analyzing the demographic characteristics, the female(68.4%) were more than the male, and 30-39 years old(53.3%) were the most generation in the PATP participants. As a result of frequency analysis by all subjects, gender and age, 78.4% of the respondents had never participated in PATP before. The most duration of the PATP was 30 to 60 minutes(24.6%). 73.5% of the respondents answered that it was not feeling difficult at all to the intensity of PATP, and 94.8% of the respondents were satisfied with the intensity of PATP. The most respondents preferred to participate again with if the new PATP starts(97.2%) and to join the new PATP with his or her family members(85.7%). In addition, the participants under the age of 39(24.3%) perceived that the effect of improving physical fitness by PATP was higher than over 40 years of age(11.9%). As a result of logistic regression analysis, it was found that only the age had a significant effect(p<.01) on intensity of PATP. It means that the perceived intensity of PATP was different between the older and young generation. However, the PATP was not designed to meet the participants age and fitness levels, and even the general exercise prescription guidelines based on professional scientific data such as exercise frequency, exercise intensity, exercise time, exercise type, and characteristics of the participants in the spaces. In conclusion, to encourage and promote the participants motivation and health-related fitness level in the spaces for the future. The various type of PATP that include a few different intensities for all genders and age groups, and a customized program based on systematic and scientific exercise prescription guidelines.