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.
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.
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 The purpose of this study was to investigate the risk factors for anterior cruciate ligament injury using the Landing Error Scoring System (LESS) and muscle activity during the drop vertical jump for overweight females. METHODS The body mass index was 18.5-22.9 kg/㎡ for normal weight females and 23-24.9 kg/㎡ for overweight females among 10 participants aged 20-30 years classified into groups of participants without any injury history and those who were right-footed. An automatic heigh-tweight machine, body composition analyzer, diagnostic imaging, electromyography with the LESS, and muscle activity analysis were used for measurements. The difference in muscle activity between the normal weight and overweight females was evaluated by independent t-test. RESULTS Overweight females had a smaller angle of knee bending during the drop vertical landing, leading to a smaller knee curve angle. In addition, they landed with an unbalanced foot touch on the ground inclined backward, thereby breaking the whole body balance. Overweight females had an incorrect posture compared with normal weight females, with higher LESS points. The muscle activity of the rectus femoris was higher than that of the biceps femoris, indicating a higher load on the muscle. CONCLUSIONS Overweight females take more load on the knee joint and cannot absorb the impact force properly. These results suggest a higher risk of anterior cruciate ligament injury in overweight females.
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 characterize the kinematic variables of stair climbing in adult women by analyzing the effects of varying heel heights on their climbing behavior. METHODS A total of 24 adult women (age: 22.08±1.28years; height: 160.43±4.30cm; weight: 54.10±6.39kg) participated in this study. All subjects wore the same type of high heels with heights of 1cm, 5cm, and 7cm while performing stair climbing on stairs measuring 18cm in height. Ten infrared cameras (200Hz) and ground reaction force sensors (1000Hz) were set up on the stairs, along with an 8-channel electromyography system (1000Hz) to analyze the maximum moments at each joint and the muscle activation during stair climbing. Data were analyzed using IBM SPSS Statistics version 27.0 (IBM., USA). All variables underwent the Shapiro–Wilk normality test, with repeated measure analysis of variance or the Friedman test applied based on the results. Post hoc tests were conducted using the LSD test or Wilcoxon signed-rank test. RESULTS Our study found four key findings. First, a significant decrease in maximum dorsiflexion, plantarflexion, inversion, and adduction moments of the ankle joint was observed with increasing heel height. Second, the maximum extension, adduction, and external rotation moments of the knee joint significantly decreased as heel height increased, while the maximum abduction and internal rotation moments significantly increased. Third, the maximum flexion, extension, and abduction moments of the hip joint significantly increased with higher heel heights. Fourth, muscle activity of the rectus femoris, vastus medialis, vastus lateralis, semitendinosus, and gastrocnemius decreased with increasing heel height compared to walking; however, muscle activity in the tensor fasciae latae increased. CONCLUSIONS The results of this study suggest that as heel height increases, the risk of injury may rise due to limited ankle use and increased moments in the knee and hip joints, potentially leading to muscle strength imbalances in adult women, particularly through the overuse of specific muscles.
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.
