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.
The human foot is only part that directly contact between the body and the external environment, and is ideally positioned to provide sensory information to the Central Nervous System (CNS) during static and dynamic tasks. Through cutaneous mechanoreceptors located in the dermis, the foot is able to recognize touch pressure and vibration stimuli, which provide important feedback information used for the fine coordination of movements. The purpose of this study is to quantitatively examine the effect of changing the foot cutaneous sensory by temperature stimulus on maximal performance and muscle activation using wavelet technique. Sixteen healthy subjects volunteered to participate in this study (Male: Age 21.4±2.4years; Height 174.7±5.3츠; Weight 70.6±5.2kg; Female: Age 20.5±0.6years; Height 163.2±3.1cm; Weight 55.6±4.8kg). Sensory pressure thresholds were determined for the plantar surface of the foot using monofilament. Kinematic, kinetic and EMG data which relative to maximal performance were collected while squat jumping in each temperature condition(cool 12-15℃ normal 28-30℃ hot 45-48℃). Maximal jump height was significant higher in normal condition. Vertical GRF in normal condition showed higher peak value the other conditions. And then EMG signal were significant different between temperature conditions during maximal performance. By changed sensory feedback on temperature, one can alter maximal performance and muscle activation pattern. Cutaneous feedback is important in performance and neuromuscular control, and temperature changes significantly influence on lower extremity during maximal squat jump performance of healthy subjects.
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 The purpose of this study was to investigate the lower extremity muscles activity during forward side step by soccer field ground types. Methods Fifteen elite high school soccer players participated in this study. Muscle activation patterns were recorded at 2000 Hz during forward side step task. Surface EMG of the tibialis anterior(TA), soleus(SOL), medial gastrocnemius(MG), lateral gastrocnemius(LG), peroneus brevis(PB) muscle was recorded, and the root mean square of the EMG was normalized, using a maximum voluntary isometric contraction(%MVIC). One-way repeated ANOVA was used for comparison among three soccer field ground types(natural grass, artificial turf, hard ground). Results Artificial turf displayed greater soleus and peroneus brevis activities compare to natural grass during forward side step task. Conclusions The relationship between increased soleus and peroneus brevis activation and greater incidence of injury in artificial turf versus natural grass requires further study. Soccer players routinely training on artificial turf for prolonged periods should be carefully monitored.
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 The purpose of this study is to investigate the effects of grip width and hand orientation on muscle activities of upper body during the lat pull-down. Methods Eight healthy men performed the 6 grip variations (3 grip width × 2 hand orientation) using an experimentally determined load of 70% of 1 repetition maximum. Five trials were analyzed for each grip type. Participants maintained a cadence of 2-second concentric and 2-second eccentric phases. The grip widths were normalized for each individual by using their biacromial diameter (100%), and then set the grip width 50% of biacromial diameter and 150% of biacromial diameter. Surface EMG of the latissimus dorsi, pectoralis major, infraspinatus, biceps brachii, triceps brachii, rectus abdominis, erector spinae and middle trapezius was recorded, and the root mean square of the EMG was normalized, using a maximum isometric voluntary contraction. Results Latissimus dorsi showed higher muscle activities in 100% grip width than those of 50% grip width. Pectoralis major and rectus abdominis showed higher muscle activities in 50% and 100% grip width than those of 150% grip width. Middle trapezius showed higher muscle activities in 150% grip width than those of 50% grip width. Conclusions Two-way repeated measures ANOVA for each muscle revealed that latissimus dorsi and middle trapezius (the posterior muscles of trunk) showed higher muscle activities in wide grip, on the other hand, pectoralis major and rectus abdominis (the posterior muscles of trunk) showed higher muscle activities in narrow grip.
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 This study aimed to explore the functional movement in rope climbing. METHODS The rope climbing experiment included 16 healthy young male participants, and the methods of hand, cross-leg, and foot-hooking climbing were employed. The muscle activity and joint range of motion were measured and analyzed using EMG (Electromyography) and IMU (Inertial Measurement Unit) sensors. One-way analysis of variance was conducted (α<.05). RESULTS The activity of the forearm and biceps muscle was lower in cross-leg and foot-hooking climbing compared to hand climbing (p<.01), and the rectus femoris muscle activity in cross-leg climbing was smaller than that in hand climbing (p<.05). Furthermore, the adductor muscle activity in cross-leg climbing was higher than that of other types (p<.01). The range of motion for the elbow and shoulder flexion was smaller in hand climbing than in other types (p<.05); furthermore, the range of motion in the pelvis, thigh, and knee joint was the smallest in cross-leg climbing (p<.05). CONCLUSIONS Because the pulling muscles such as the forearm, biceps, pectoralis major, and latissimus dorsi play an important role in the entire climbing motion, it is necessary to train the upper-body pulling-muscle group along with strengthening the core and lower body muscles.
