PURPOSE The purpose of this study was to verify the support effect of muscle activity and stability according to walking conditions (Level, Ramp, and Stair) before and after wearing a suit with a 12kg heavy weight load. METHODS To accomplish the purpose of the study, subjects (n=10) underwent Electromyography (EMG) measurement under the same conditions for 10 different muscles, and COP width was calculated through foot pressure measurement. The experimental movement was level walking, Ramp walking, and stair walking, each carrying a 12kg load, and measured once before and after wearing a wearable suit. RESULTS Electrolyography (EMG) measurement revealed a significant difference in the average EMG values of muscle activity of R.RF in level walking(p<.05), R.RF and L.RF in ramp walking(p<.01), L.RF and L.BF in stair walking (p<.05). COP width measurement revealed a significant difference in the reduction of COP width in all walks (level walking, ramp walking, stair) (p<.05, p<.01, p<.001). CONCLUSIONS The effects of wearing a wearable suit are as follows. First, the wearable suit has a significant effect of assisting the Rectus Femoris muscle. Second, there is a gait stability effect by wearing a wearable suit.
Purpose This is to provide essential data for training necessary for sweeping through the analysis of muscle activity generated at this time and how much sweeping and what trajectory moves the stone when the movement of the stone is controlled through sweeping. Methods To check and record the distance between the stones by checking the stop position of the stone made by sweeping each section, the length (progress distance) and width (progress direction) were recorded using a reference table and a record preparation table. With the EMG attached, a total of 60 sweeps were made 20 times each from the beginning of the section to the end of the section. Sweeping subjects were asked to sweep as much as possible under the same conditions in all three sections. Results As a result of the study, the muscle mobilization patterns of the 1st and 2nd sections of the stone with the faster speed and the 3rd section with the stone's slower speed appeared differently. It was confirmed that the sweeping motion of curling is a motion that is used evenly among the muscles of the upper extremity, and it can be verified that it is a suitable item for the development of upper body muscles. Also, the right deltoid's muscle activity rate during push and the right triceps brachii during pull was high. Conclusion Each section of the stone's sweeping effect is an exercise that has many variables, such as changes in atmospheric temperature and humidity, changes in ice temperature, temperature-size-number of pebbles, and the edge state-resilience of stones, etc. It is judged that experience can cope with these variables and requires training.
Purpose The purpose of this study is to overcome the shortcomings of 109C(Forward 4 ½ somersault) skill(Level 3.7) for two members of the men’s national diving team(YHR, KYN). Methods For qualitative analysis of the performed skill, three high-speed cameras and water-attached EMGs consisting of a total of ten placements were used. We instructed the two players to perform single-leg jump and double-leg jumps a total of three times each. Results The results of this study indicate that YHR and KYN appeared to increase their time or maintain the same time compared to the previous phase and displacement appeared higher when skill success occurred after the double-leg jump. The Shoulder & hip joints of YHR, KYN appeared larger in E2 and the hip joint of KYN appeared to increase in E1. Single-leg jump appeared similar or decreased the performed time of the previous phase in the last P5. YHR appeared larger only at a hip joint angle and KYN appeared smaller at the hip joint. The muscle activity(iEMG) of the two players appeared greater during skill failure than most of the muscles. Conclusions When perfectly performing 109C skills, the acquisition of medals in international competitions is possible. Therefore, in the future, it is necessary to study all of the variables that pertain to 109C.
Purpose The purpose of this study was to evaluate the effect of detachable forefoot outsole on muscle activity of the lower extremity during downhill walking. Methods Thirteen male university students (age: 23.5±2.1 yrs, height: 175.7±4.6 cm, weight: 651.9±55.5 N) who have no musculoskeletal disorder were recruited as the subjects. Each subject walked down 20° ramp with forefoot’s design for the detachable outsole’s angle(5°, 10° and 20°) and type(A and B). To assess the myoelectric activities of selected muscles, six of surface EMG(QEMG8, Laxtha Inc. korea, sampling frequency = 1,024 Hz, gain = 1,000, input impedance > 1012 Ω, CMRR > 100 dB) electrodes with on-site pre-amplification circuitry were attached to ES, RF, BF, TA, LG, and MG. For each dependent variable, two-way ANOVA with repeated measures was used to determine whether there were significant differences among forefoot’s design for the detachable outsole’s angle and type (p<.05). When correlation effect was not statistically significant, post hoc analyses were performed using the multiple comparison through bonferroni, and if correlation effect was statistically significant, one-way ANOVA was performed as for the form of outsole which is an inter-group variable in order to find out simple main effect, and the paired t-test was performed to find out the angle of outsole, which is an intra-group variable. Results In IDLS phase, In terms of Rectus Femoris, 10°-B outsole showed statistically higher muscle movement than 5°-B, 5°-A outsole showed statistically higher muscle movement than 5°-B, 20°-A outsole showed statistically higher muscle movement than 20°-B. Among these outsoles, Conclusion 5°-B outsole was found to the most useful outsole for improving stability and controlling the bodily movement due to the body weight load when walking down the ramp.
The purpose of this study was to determine how acute active pc-video game affects kinematic variables and muscle activities of adolescents. Fourteen middle school students(age: 15.9±0.7 yrs, height: 171.3±6.1cm, weight: 60.0±5.4 kg, right handed) who have no musculoskeletal disorder were recruited as the subject according to having experience in using the pc-video game for more than six months. Maximum angle, angular velocity, and muscle activity of the upper extremity were determined for each trial. For each dependent variable, a paired t-test was performed to test if significant difference existed between pre- and post a 60 minute active pc-video game(p<.05). This study found that one hour pc-video game hour may not affect on movement and ROM of the finger and the wrist, whereas it may have an effect on muscle activity of the upper extremity. It seems that repetitive movement pattern during an active pc-video game may hinder muscle activity of adolescents’ upper extremity. Part of the increase in musculoskeletal disorders is linked to the amount of time adolescents are allowed to play video games. This study found that an active pc-video game appears to have negative effects on the upper extremity muscles. Since wrist movements are continually repeated throughout the video game, carpal tunnel syndrome may possibly be caused by long-term exposure to video games.
The past few decades has seen increasing kinematic studies using surface electoromyography (EMG) in archery, however there has been no such specific study in Korean traditional archery. The purpose of this study was to evaluate EMGs during archery shooting motion in Korean traditional archers. Ten men Korean traditional archers were participated, and divided into two groups according to the shooting stance; parallel stance group(PSG, n=5) and oblique stance group(OSG, n=5). The surface EMGs were measured 12 muscles during shooting motion of five events including Junbi(Set), Geogung(Set up), Manjak(Full draw), Balsi(Release), Machigi(Ending). At the result, muscle activity of posterior deltoid, trapezius, rhomboid major, latissimus dorsi, biceps brachii, forearm extensor bundle, triceps brachii, levator scapulae significantly increased at event of full draw and release, then significantly decreased again at event of ending, respectively(p<.01, p<.001). The muscle activity of erector spinae(ES) was also significantly increased at event of full draw and release(p<.01, p<.001), while no significant changes in muscles of rectus abdominis, rectus femoris(RF), gluteus maximus. As a result of comparing PSG and OSG, muscle activity of RF in OSG was higher than PSG at event of release(p<.05), it remained until event of ending(p<.05). On the other hand, the higher the tension of the bow, the higher the muscle activity of the draw arm at event of release(p<.05). These results suggest that when Korean traditional archery shooting, both side arm and back muscles are more activated than the abdomen, leg and hip muscles. The parallel stance might suppress the muscle activity of the lower extremities to twist the upper body. And the higher bowstring tension needs to increase of muscle strength in BB of draw arm.
Purpose This study was to analyze and compare series of muscle activities during plank exercises with use of togu-jumper. Methods Ten male subjects (age 26.9±1.7 yrs, height 172.2±5.7 cm, weight 66.5±7.5 kg) who have no musculoskeletal disorder with one's upper or lower limb were selected as subjects. To analyze and compare series of muscle activity, five of surface EMG electrodes were attached to the upper rectus abdominis (URA), lower rectus abdominis (LRA), external abdominal oblique (EO), erector spinae (ES) and gluteus maximus (GM). Each subject did plank exercise on stable support surfaces (normal surfaces) and unstable support surfaces with the togu-jumper. For each dependent variable, one-way ANOVA with repeated measures were performed with significance level p<.05. Contrasts were performed to execute post tests for results with statistical significance. Results The study showed that the average IEMG values of URA and LRA increased in Upper (Togu-jumper used upper limb) compared to normal surfaces. This is perhaps because the effects of URA more than any other muscles for body stability. Furthermore, the peak IEMG values of LRA increased in Upper and Lower (Togu-jumper used lower limb) compared to normal surfaces. In addition, peak IEMG values of EO increased in Upper compared to Normal. This may have resulted due to momentary strong muscle activity in LRA and EO to correct body posture and balance. Therefore, using Togu-jumper on upper limb maximizes the performance of core training in plank exercise. Conclusions The study may be further applied to a method for effective training. It is considered that research and analysis has to be further done on modified plank exercise. Additionally, it is necessary to analyze not only global muscle but also local muscle, as a comprehensive research, to suggest ideal method for plank exercise.
The purpose of this research is to investigate the factors affecting the performance capability of lunge movements by performing lunge movements which are commonly used as a method of instant physical movement in sports with a kinetic analysis including an EMG analysis. This research targeted 14 skilled fencers and made the subjects perform kick-lunges which allow them to go farthest from their positions and performed an analysis on such, applying a 3D motion analysis system and an EMG system. The subjects performed kick-lunges in two movements; one with a preliminary movement and the other without it and those are performed with both dominant leg and non-dominant leg. The result of this research is as follows. The lunges with a preliminary movement showed higher performance capability than those without it. Furthermore, as the level of skills gets higher, the length of lunges gets longer, and it seemed that a tactical mechanism shortening exercise performance times was used as a mechanism to control the impulse coming from such lengthened lunges. In addition, a difference appeared in mechanical factors such as moment and power in a dominant leg movement and it seemed to result from a difference in an functional capability using muscles.
Purpose The purpose of this study was to investigate the changes of gait patterns and muscle activations according to dual tasks during stair ascending. Methods Twelve sedentary young male adults(Age: 27.0±1.8 yrs, Weight: 65.8±9.9 kg) without any lower extremity injuries participated in the study. Participants performed stair walking up 7 floors and their ascending motion on each floor was analyzed according to dual tasks. A wireless electromyography (EMG) were attached on the Rectus Femoris(RF), Biceps Femoris(BF), Gastrocnemius(GN), Tibialis Anterior(TA) muscle to calculate integrated EMG(iEMG) and co-contraction index(CI). Chest and left heel accelerometer signal were recorded by wireless accelerometer and those were used to calculate approximate entropy(ApEn) for analyzing gait pattern. All analyses were performed with SPSS 21.0 and for repeated measured ANOVA and Post-hoc was LSD. Results The results of this study indicated that dual task appeared to increase their time, CI and there were a statistically significant difference in most muscle on each floors compared to the non dual tasks. Also, ApEn were a statistically significant difference in only left and right direction than non dual task. Subjects showed more irregular pattern and instability muscle activation response during dual tasks. Conclusion Because there are many dangers often use of stairs in everyday life, in the future, we have to make a lot of efforts to prevent fall.
PURPOSE This study aimed to identify the lower limb muscle activity based on direction prediction presence or absence and gender during side cutting in healthy college students. METHODS The study participants included 14 healthy males and females (8 males; 6 females). All participants ran at full speed for a distance of 12m, and side-cutting was carried out at 45 degrees in a randomly indicated direction and in a fixed direction. Simultaneously, data regarding vastus medialis, vastus lateralis, semitendinosus, and biceps femoris muscle activity of the dominant leg were collected using an electromyography sensor, and data regarding vertical acceleration were collected using an inertial sensor attached to the pelvis. A sync webcam was used for obtaining the initial contact of side cutting and the stance period time. During the 10 milliseconds (pre-activation) prior to the initial contact and 50% of the stance phase (loading phase), vastus medialis, vastus lateralis, semitendinosus, and biceps femoris average muscle activity and hamstring to quadriceps ratio included as variables. RESULTS During the pre-activation and loading phase, the vastus medialis muscle activity of the male group was higher in the unexpected condition than in the expected condition. Furthermore, hamstring to quadriceps ratio was confirmed to be lower under unexpected condition compared to under expected condition during on loading phase. CONCLUSIONS The study results suggest that the risk of anterior cruciate ligament injury may increase with side cutting under unpredictable conditions. It is expected to provide useful information for identifying factors related to knee injury in the general population.
