Significant Differences In Muscle Activity Research Articles

Assessment of Muscle Activity During a Deadlift Performed by Construction Workers

Construction work is physically demanding. The tasks involved in this professional occupation physically exhaust workers and put them at high risk of injury. This work aimed to analyze muscle fatigue in civil construction workers with and without a history of physical activity. For this purpose, the muscle activity of the biceps femoris, trapezius transversalis, and erector spinae longissimus muscles was evaluated using surface electromyography. Eleven male civil construction workers aged 26 to 52 years (38.00 ± 9.60), seven of whom were untrained (N = 7) and four of whom were trained (N = 4), participated in this study. Each subject completed two assessments at two different times. A questionnaire was completed for the first assessment, and each subject’s maximum repetition for the deadlift exercise was assessed. In the second assessment, the subjects were assessed while performing the deadlift in four different situations: 50%RM at rest, 70%RM at rest, 70%RM at fatigue, and 50%RM at fatigue. The trained construction workers had higher levels of muscle activity, and there were no significant differences in muscle activation between the fatigued and non-fatigued sets. There appears to be a strong influence of physical exercise on muscle activity and fatigue in civil construction workers.

Comparison of Muscular Activity During Running with New and Used Military Boots and Running Footwears in Healthy Individuals: A Clinical Trial Study

Background: The type of footwear worn by military personnel and others could increase the risk of overuse injuries. Objectives: This study aimed to compare muscular activity during running with new and used military boots and running footwear in healthy individuals. Methods: Thirty healthy males were given a new pair of running footwear (n = 15) and thermoplastic polyurethane military boots (n = 15). Participants in each group were asked to wear these shoes for 6 months. Electromyographic activity of the dominant limb muscles was recorded during running at a speed of 3.3 m/s before and after 6 months. Results: The results indicated significant differences in muscle activity based on the type of footwear worn during various phases of running. Specifically, muscles such as the tibialis anterior, vastus lateralis, rectus femoris, biceps femoris, and semitendinosus showed varied activity during phases such as loading, mid-stance, and push-off. Additionally, there were significant effects of time on certain muscles, including the tibialis anterior and gastrocnemius medialis during the push-off phase. Interactions between footwear type and time were observed for the semitendinosus and gluteus medius during the loading phase, and the gastrocnemius medialis during the push-off phase. Conclusions: The results of this study indicate a decrease in muscle activity for most lower limb muscles in the military boots group compared to the running footwear group during the stance phase of running. The magnitude of gastrocnemius medialis activity increased in the military boots group (but not in the running footwear group) from pre-test to post-test during the push-off phase.

The Effects of the Leg Position on the Nordic Hamstring Exercise Eccentric Force: A Randomized Cross-Over Study

Given the posterior chain configuration, it is anticipated that tibial positioning influences hamstring recruitment; medial hamstrings should be more activated during medial rotation, while lateral hamstrings should be more activated during lateral rotation. However, most studies showing this pattern have focused on concentric or isometric strength, leaving the influence on eccentric strength fairly unknown. Therefore, the aim of this study was to investigate the electromyographic response of the hamstring muscles during Nordic hamstring exercises in three leg positions: internal rotation, external rotation, and neutral. This study encompassed a randomized crossover study and used surface electromyography to analyze the activity of the biceps femoris and semitendinosus muscles during the Nordic hamstring exercise, in the three positions. Results indicated no statistically significant differences in muscle activation between positions or sides (p > 0.05), though small effect sizes were observed for the biceps femoris in different positions (η2 = 0.01–0.03). Furthermore, the internal rotation position generally elicited the highest muscle activations. Notably, biceps femoris muscles exhibited higher activations compared to semitendinosus muscles, with the greatest differences seen in the internal rotation position. This suggests that tibial rotation influences hamstring recruitment patterns; however, it was lower than expected.

Trunk muscle activation of core stabilization exercises in subjects with and without chronic low back pain.

Weakness and atrophy in trunk muscles have been associated with chronic low back pain (CLBP). This study aimed to identify isometric exercises resulting the highest trunk muscle activity for individuals with and without CLBP. Fourteen males with CLBP and 15 healthy age-matched healthy subjects were recruited for this study. Muscle activity during maximal voluntary isometric contraction (MVIC) was measured for a comparative reference with surface electromyography (sEMG) from six trunk muscles. Thereafter maximum EMG amplitude values were measured during eleven trunk stability exercises. The maximal EMG activity in each exercise relative to the MVICs was analyzed using generalizing estimating equations (GEE) models with the unstructured correlation structure. The GEE models showed statistically significant differences in muscle activity between exercises within both groups (p< 0.001), with no significant differences between groups (p> 0.05). The highest muscle activity was achieved with the hip flexion machine for multifidus, side pull with a resistance band for lumbar extensors, side and single-arm cable pull exercises for thoracic extensors, rotary plank and the hip flexion machine for abdominal. This study found five isometric trunk exercises that exhibited highest muscle activity depending on muscle tested, with no significant difference between individuals with and without CLBP.

Effect of scapular posterior tilting exercise on scapular muscle activities in men and women with a rounded shoulder posture

Round-shoulder posture (RSP) is a common postural condition, characterized by protraction, downward rotation, anterior tilting and internal rotation of the scapula. RSP can lead to shoulder dysfunction. Different methods have been proposed for rehabilitating and correcting the altered posture in RSP including stretching, strengthening exercises, and shoulder brace or taping. However, the findings are controversial and studies are ongoing to develop more effective method. The present study is aimed at investigating the effects of scapular posterior tilting (SPT) exercise in different support positions on scapular muscle activities in men and women with RSP. In a prospective observational clinical study, we assessed demographic, basic clinical parameters and study variables of the subjects with RSP (n = 20) (men/women = 9/11) attending Daegu University in Gyeongsan, South Korea. To do so, we compared electromyographic (EMG) activities of lower trapezius and serratus anterior muscles between men and women with RSP during SPT exercise on four different support surfaces to determine any difference in the EMG activities. The results revealed that women showed significant differences in EMG activities in the lower and left upper trapezius and serratus anterior muscles, while men showed significant differences in EMG activity only in the lower trapezius muscle during SPT exercise on four different surfaces (P < 0.05). The post-hoc analysis revealed significantly greater EMG activity values in the lower trapezius and serratus anterior muscles during SPT exercise on the upper body unstable surface and whole-body unstable surface (p < 0.05). Independent t-tests after the Bonferroni correction showed no significant differences in muscle activities between men and women on the four different surfaces (p > 0.0125).

Exploring lower limb muscle activity and performance variations during instrumented Sit-to-Stand-to-Sit in sedentary individuals: Influence of limb dominance and testing modalities

Purposeto explore lower limb muscle activity concerning limb dominance, as well as variations in force and power during the standing up and sitting down phases of the instrumented sit-to-stand-to-sit test in sedentary individuals, across isokinetic and isotonic modalities. Methods33 sedentary individuals underwent testing using a functional electromechanical dynamometer in both isokinetic and isotonic modes, accompanied by surface electromyography. ResultsIn the isokinetic mode, the non-dominant gastrocnemius medialis and vastus medialis exhibited significantly (p < 0.05) higher muscle activity values during the standing up and sitting down phase compared to dominant counterparts. In the isotonic mode standing up phase, significant differences in muscle activity were noted for non-dominant gastrocnemius medialis, vastus medialis, and biceps femoris compared to their dominant counterparts. The sitting down phase in isotonic mode showed higher muscle activity for non-dominant vastus medialis compared to dominant vastus medialis. Regard to performance outcomes, significantly lower (p < 0.0001) values were observed for standing up (12.7 ± 5.1 N/kg) compared to sitting down (15.9 ± 6.1 N/kg) peak force, as well as for standing up (18.7 ± 7.8 W/kg) compared to sitting down (25.9 ± 9.7 W/kg) peak power in isokinetic mode. In isotonic mode, lower values were found for sitting down (6.5 (6.3–7.1) N/kg) compared to standing up (7.8 (7.3–8.9) N/kg) peak force and for sitting down (18.5 (13.2–21.7) W/kg) compared to standing up (33.7 (22.8–41.6) W/kg) peak power. ConclusionsLimb dominance influences lower-limb muscle activity during the instrumented sit-to-stand-to-sit test, and the choice of testing mode (isokinetic or isotonic) affects muscle engagement and performance outcomes.

Neural Respiratory Drive During Different Dyspnea Relief Positions and Breathing Exercises in Individuals With COPD.

When the work load of the respiratory muscles increases and/or their capacity decreases in individuals with COPD, respiratory muscle activation increases to maintain gas exchange and respiratory mechanics, and perception of dyspnea occurs. The present study aimed to compare diaphragm and accessory respiratory muscle activation during normal breathing, pursed-lip breathing, and breathing control in different dyspnea relief positions, supine and side lying. A cross-sectional study design was used. Sixteen individuals with COPD age between 40-75 y were included. Pulmonary function was evaluated by spirometry, muscle activation by surface electromyography, and dyspnea by the modified Borg scale. Muscle activation was measured in the diaphragm, scalene, sternocleidomastoid, and parasternal muscles. The evaluation was made in the dyspnea relief positions (sitting leaning forward, sitting leaning forward at a table, leaning forward with back against a wall, standing leaning forward, and high lying), seated erect, supine, and side lying. There were significant differences between the 8 positions (P < .001). There was no significant difference in muscle activation between sitting leaning forward and sitting leaning forward at a table position with analyzing post hoc test results (P > .99 for each muscle). However, muscle activation was lower in these 2 positions than in the other positions (P < .001 for each muscle). Muscle activation was greater in the supine position than in the other positions (P < .001 for each muscle). No difference was observed in muscle activation between the seated erect, leaning forward with back against a wall, standing leaning forward, high-lying, or side-lying positions (P > .05 for each muscle with a minimum P value of .09). The use of sitting leaning forward and sitting leaning forward at a table positions together with breathing control may help people with COPD to achieve more effective dyspnea relief and greater energy efficiency.

Influence of Amputation on Kinetic Chain Musculature Activity During Basic and Modified Core Exercises.

Core strength is vital for athletic performance, and many more exercises that involve the kinetic chain have been designed for able-bodied athletes. Disabilities that impair the kinetic chain can reduce the effectiveness of strength training. However, the impact of amputation on core strength training of people with disabilities and its underlying mechanism remains unclear. This study aimed to evaluate the muscle activation patterns and levels in athletes with amputation during 4 basic and modified weight-bearing core strength-training exercises. Fifteen elite athletes with unilateral amputation (170.6 [7.3]cm; 63.9 [11.9]kg; 25.9 [5.3]y) volunteered for this study. Surface electromyography was used to measure the muscle activity mainly in the lumbopelvic-hip complex-stabilizing muscles during 4 kinetic chain trunk exercises with and without modifications. The significance level was set at α = .05. The results showed a significant difference in muscle activation between different body sides (P < .05). Specifically, amputation on the support position resulted in a diagonal pattern of muscle activation, and amputation on the free distal segments resulted in a unilateral dominant pattern with higher activation in muscles on the nonamputated side (P < .05). Modifications led to significant decreases in muscle activation asymmetry index (P < .05). Amputation caused muscle activation asymmetry and 2 activation patterns. Modifications by enhancing proximal stability and adjusting distal loading effectively reduced the asymmetry of muscle activation. Coaches and clinicians can use these results to tailor exercises for athletes with disabilities in training and rehabilitation.

Identification of the Biomechanical Response of the Muscles That Contract the Most during Disfluencies in Stuttered Speech.

Stuttering, affecting approximately 1% of the global population, is a complex speech disorder significantly impacting individuals' quality of life. Prior studies using electromyography (EMG) to examine orofacial muscle activity in stuttering have presented mixed results, highlighting the variability in neuromuscular responses during stuttering episodes. Fifty-five participants with stuttering and 30 individuals without stuttering, aged between 18 and 40, participated in the study. EMG signals from five facial and cervical muscles were recorded during speech tasks and analyzed for mean amplitude and frequency activity in the 5-15 Hz range to identify significant differences. Upon analysis of the 5-15 Hz frequency range, a higher average amplitude was observed in the zygomaticus major muscle for participants while stuttering (p < 0.05). Additionally, when assessing the overall EMG signal amplitude, a higher average amplitude was observed in samples obtained from disfluencies in participants who did not stutter, particularly in the depressor anguli oris muscle (p < 0.05). Significant differences in muscle activity were observed between the two groups, particularly in the depressor anguli oris and zygomaticus major muscles. These results suggest that the underlying neuromuscular mechanisms of stuttering might involve subtle aspects of timing and coordination in muscle activation. Therefore, these findings may contribute to the field of biosensors by providing valuable perspectives on neuromuscular mechanisms and the relevance of electromyography in stuttering research. Further research in this area has the potential to advance the development of biosensor technology for language-related applications and therapeutic interventions in stuttering.

Does dual‐tasking affect the ability to generate anticipatory postural adjustments in young adults?

AbstractThe aim of this study was to investigate how additional cognitive tasks (Stroop test and counting backwards task) influence young adults' ability to generate appropriate postural responses while standing on a continuously oscillating platform. Twenty young adults (25.95 ± 2.97 years) stood on a moving platform which was translated in the anterior–posterior direction at three different frequencies (0.10, 0.25 and 0.50 Hz) in three dual‐task conditions (counting backwards task, a Stroop task or no additional cognitive task). Postural muscle onset latencies and tonic activity levels of the leg muscles were measured through surface electromyography; the number of steps taken and cognitive errors made were recorded. Results showed no significant differences in muscle activity between dual and single‐tasking conditions nor between the two dual tasking conditions. Cognitive errors were made in the counting backwards task but not the Stroop task. A frequency effect was identified with participants showing greater tonic activity in rectus femoris (p = 0.012), gastrocnemius medialis (p = 0.016) and bicep femoris (p = 0.043) at 0.5 Hz, as well as earlier muscle activation in tibialis anterior, gastrocnemius medialis and bicep femoris (p &lt; 0.001) at 0.50 Hz. Transition and steady state muscle onset latencies were only significantly different for gastrocnemius medialis at 0.25 Hz (p = 0.001). Dual tasking did not seem to influence anticipatory postural adjustments in young adults; however, perturbation intensities did. The differences observed in the number of cognitive errors made could be indicative of the regional cortical activations and overlapping demand for resources interfering with balance control, though cortical activation was not recorded. Future research should include detailed cognitive behavior, including cortical activations and task reaction times to better understand the allocation of attentional resources during perturbed balance dual tasking.

People With Low Back Pain Exhibit Higher Trunk Muscle Activity and Impaired Postural Control During Static and Dynamic Functional Tasks: A Cross-Sectional Study.

The study compared superficial trunk muscle activity and postural control among an active extension subgroup of people with nonspecific chronic low back pain (AE-NSCLBP) with painfree controls during functional tasks. Thirty-two people (17 people with low back pain [LBP] and 15 painfree controls) participated in this study. Muscle activity of 5 trunk muscles and postural control were investigated during both standing tasks (eyes open/closed; single/double-leg balance) and dynamic functional tasks (spinal forward flexion and return, and a sit to stand transfer). Results showed that during single-leg standing, people with AE-NSCLBP exhibit higher muscle activity than painfree controls for 3 trunk muscles, especially with their eyes closed. There were no significant differences in muscle activity between eye conditions during double-leg standing and sit to stand transfer, forward flexion, and return from flexion. The AE-NSCLBP subgroup also demonstrated significantly impaired postural control (lower time to boundary) in 4 of 8 conditions, especially during single-leg standing and with their eyes closed. These findings show people with LBP typically demonstrated greater trunk muscle activity and poorer postural control while maintaining standing posture. This pattern was most evident when the postural challenge was higher, such as single-leg standing or with eyes closed. While this study design cannot infer causality, these findings have implications for LBP rehabilitation, particularly regarding approaches which seek to alter muscle activation among people with LBP.

Lower-Limb Myoelectric Calibration Postures for Transtibial Prostheses.

The use of an agonist-antagonist muscle pair for myoelectric control of a transtibial prosthesis requires normalizing the myoelectric signals and identifying their co-contraction signature. Extensive literature has explored the relationship between body posture and lower-limb muscle activation level using surface electromyography (EMG), but it is unknown how these relationships hold after amputation. Using a virtual tracking task, this study compares the effect of three different calibration postures (seated, standing, dynamic) on user tracking ability while in two tracking postures (seated, standing) for 18 able-bodied (AB) subjects and 9 subjects with transtibial (TT) amputation. As expected, AB subjects produced statistically significant differences in muscle activation for gastrocnemius (GAS) when seated vs. standing during calibration (p = 8.8e-4), but not for tibialis anterior (TA) (p = 0.76). TT subjects, however, showed no significant differences in GAS or TA between seated and standing (p = 0.90, 0.60 respectively). It was also determined that normalizing EMG by the global maximum signal observed (standard in biomechanic analysis) is undesirable for myoelectric control. For best general results with this framework, calibration in both seated and dynamic postures is recommended, taking the normalization information from the seated posture and the narrowest co-contraction slopes from the two.

Surface electromyography of the vastus lateralis and gluteus medius muscles in post-operative T3-L3 hemilaminectomy dogs: a prospective controlled observational study.

The objective of this study was to determine if surface electromyography (sEMG) demonstrates differences in muscle activation between normal and dogs recovering from spinal cord injury due to intervertebral disk extrusion. Two groups of client-owned small-breed chondrodysplastic-type dogs were tested. Group 1 consisted of seven ambulatory paraparetic dogs that had undergone a hemilaminectomy procedure in the T3-L3 region for intervertebral disk extrusion 1 month prior. Group 2 was made up of seven normal dogs that had no history of intervertebral disk disease or spinal surgery. Each subject walked 10 feet on a nonslip surface for at least five gait cycles for the sEMG to capture muscle activation of the vastus lateralis and gluteus medius, bilaterally. Muscle activation was quantified as the total myoelectric output area under the curve, averaged across all gait cycles. Muscle activation was significantly greater in the post-operative hemilaminectomy group (p = 0.012). There was a significant difference in muscle activation between each hindlimb in the post-operative hemilaminectomy group, but not in the normal group. The muscle activation was significantly lower on the side that underwent surgery compared to the opposite limb (p = 0.0034). Post-operative hemilaminectomy dogs have greater hindlimb muscle activation compared to normal dogs, which likely represents a lack of descending inhibition secondary to upper motor neuron syndrome. The side of surgery is correlated with decreased muscle activation. Surface EMG can be used to evaluate muscle activity in dogs recovering from spinal decompression surgery.

Upper Extremity Electromyography During Bouldering: Research Report

Background: Despite the growing popularity of bouldering, little is known about the degree and variabilityof muscle activation that occurs while solving bouldering problems. The purpose of this study was to explorethe electromyography of eight upper extremity and trunk muscles during a session of indoor bouldering whilecompleting four different problems.Methods: Eleven climbers with self-reported ability to climb a V-scale V4 problem grade or higher and regularlyboulder at least two days/week for at least six months participated in this study. Electromyography was used torecord muscle activity of the flexor digitorum superficialis, extensor carpi radialis longus, biceps brachii, tricepsbrachii, anterior deltoid, middle deltoid, posterior deltoid, and latissimus dorsi.Conclusion: The highest average EMG across all four climbs occurred in the flexor digitorum superficialis,latissimus dorsi, and extensor carpi radialis brevis. Significant differences in muscle activity were noted betweenthe anterior deltoid and latissimus dorsi, flexor digitorum superficialis and biceps brachii, triceps brachii andflexor digitorum superficialis, posterior deltoid and latissimus dorsi, and triceps brachii and latissimus dorsi.This information may be useful in developing a strength and conditioning program for

The effect of EMG biofeedback training on muscle activation in an impingement population

Subacromial impingement syndrome (SAIS) is one of the most diagnosed causes of pain in the upper extremity. The purpose of this study was to investigate muscle activity between asymptomatic and SAIS shoulders on the same subject while understanding the effectiveness of EMG biofeedback training (EBFB) on bilateral overhead movements. Ten participants (7 male), that tested positive for 2/3 SAIS clinical tests, volunteered for the study. Bilateral muscle activity was measured via electrodes on the upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), and lumbar paraspinals (LP). Participants performed bilateral scapular plane overhead movements before and after EBFB. EBFB consisted of 10 bilateral repetitions of I, W, T, and Y exercises focused on reducing UT and increasing LT and SA activity. Prior to EBFB, no significant difference in muscle activity was present between sides. A significant main effect of time indicated that after EBFB both sides exhibited reduced UT activity at 60° (p=0.003) and 90° (p=0.036), LT activity was increased at all measured humeral angles (p<0.0005), and SA muscle activity was increased at 110° (p=0.001). EBFB in conjunction with scapular based exercise effectively alters muscle activity of asymptomatic and symptomatic scapular musculature.

탄력밴드를 이용한 고유수용성신경근촉진법의 안정화 운동이 몸통 및 엉덩부위 근 활성도에 미치는 영향

This study attempted to investigate body and hip muscle activities, using resistance band against 12 adult men. For this, one leg-supported pose in bridge position, skater-patterned bridge pose, bird-dog exercise in quadruped position and skater-patterned exercise pose trainings were performed. Specifically, the maximum voluntary isometric contraction (MVIC) of internal abdominal oblique, external abdominal oblique, multifidus, gluteus maximus and gluteus medius muscle was measured, using surface electromyography (sEMG) after conducting bridge pose and quadrupled exercise, and the results found the followings: In the bridge exercise and quadrupled exercise intervention-based proprioceptive neuromuscular facilitation (PNF), internal abdominal oblique and external abdominal oblique revealed a significant difference in muscle activity (p<0.05). In multifidus, gluteus maximus and gluteus medius muscle, on the contrary, no significant difference was observed in bridge exercise (p>0.05). In the quadrupled exercise intervention-based PNF, however, a significant difference of muscle activity was found (p<0.05). The above results confirm that a skater pattern which combined the single pattern of the PNF could reduce pain and enhance body stabilization through body balancing if selectively applied to those who are suffering from lumbar pain and difficulty in supporting their body weight due to weak abdominal and hip muscles and anterior pelvic tilt.

Exercises With Optimal Scapulothoracic Muscle Activation for Individuals With Paraplegia.

Individuals with paraplegia and coexisting trunk and postural control deficits rely on their upper extremities for function, which increases the risk of shoulder pain. A multifactorial etiology of shoulder pain includes "impingement" of the supraspinatus, infraspinatus, long head of the biceps tendons, and/or subacromial bursa resulting from anatomic abnormalities, intratendinous degeneration, and altered scapulothoracic kinematics and muscle activation. Targeting serratus anterior (SA) and lower trapezius (LT) activation during exercise, as part of a comprehensive plan, minimizes impingement risk by maintaining optimal shoulder alignment and kinematics during functional activities. To prevent excessive scapular upward translation, minimizing upper trapezius (UT) to SA and LT activation is also important. To determine which exercises (1) maximally activate SA and minimize UT:SA ratio and (2) maximally activate LT and minimize UT:LT ratio. Kinematic and muscle activation data were captured from 10 individuals with paraplegia during four exercises: "T," scaption (sitting), dynamic hug, and SA punch (supine). Means and ratios were normalized by percent maximum voluntary isometric contraction (MVIC) for each muscle. One-way repeated measures analysis of variance determined significant differences in muscle activation between exercises. Exercises were rank ordered: (1) maximum SA activation: SA punch, scaption, dynamic hug, "T"; (2) maximum LT activation: "T," scaption, dynamic hug, SA punch; 3) minimum UT:SA ratio: SA punch, dynamic hug, scaption, "T"; and (4) minimum UT:LT ratio: SA punch, dynamic hug, "T," scaption. Exercise elicited statistically significant changes in percent MVIC and ratios. Post hoc analyses revealed multiple significant differences between exercises (p < .05). SA punch produced the greatest SA activation and lowest ratios. Dynamic hug also produced optimal ratios, suggesting supine exercises minimize UT activation more effectively. To isolate SA activation, individuals with impaired trunk control may want to initiate strengthening exercises in supine. Participants maximally activated the LT, but they were not able to minimize UT while upright.

A Study of Different Frequencies of Repetitive Transcranial Magnetic Stimulation on Upper Extremity Muscle Activity and Hand Function in Chronic Stroke Patients

The purpose of this study was to compare the use of different frequencies of repetitive transcranial magnetic stimulation (rTMS) on the upper extremity muscle activity and hand function of chronic stroke patients. The study subjects comprised 18 chronic stroke patients: the 5 Hz rTMS group (HFG), which included nine patients who received rTMS to the affected cerebral hemisphere, and the 1 Hz low-frequency group (LFG), which had nine patients who received rTMS to the nonaffected cerebral hemisphere. The intervention was conducted three times a week for four weeks. Electromyography was used to check muscle activity, and the stroke upper extremity function test (MFT) and grip strength test were performed to check hand function. Pre- and post-evaluations were performed for both groups. A comparison between the two groups showed a significant difference in the activity of the trapezius anterior and triceps brachii muscle for the muscle activities in the HFG group (p 0.05) as well as a significant difference in the MFT results for hand function (p 0.05). In the LFG group, a significant difference was noted in the triceps brachii muscle for muscle activity (p 0.05), but no significant difference was evident in hand function (p 0.05). The comparison of the two groups showed a significant difference in muscle activity in the triceps brachii muscle (p 0.05) but no significant difference in hand function (p 0.05). This study confirmed that high-frequency rTMS has a positive effect on upper extremity muscle activity and hand function in chronic stroke patients.

Influence of Loads and Loading Position on the Muscle Activity of the Trunk and Lower Extremity during Squat Exercise.

This study aimed to investigate the effect of the load and bar position on trunk and lower extremity muscle activity during squat exercise. High bar back squats (HBBS) and low bar back squats (LBBS) were performed in random order at 50%, 60%, and 70% loads of one repetition maximum by 28 experienced healthy adult men who had been performing squats for at least one year. Before the experiment, the maximal voluntary contraction of the vastus medialis, vastus lateralis, rectus femoris, biceps femoris, rectus abdominis, transverse abdominis, external oblique, and erector spinae muscles was measured by means of surface electromyography. In addition, eccentric and concentric exercises were performed for 3 s each to measure the muscle activity. There was a significant difference in muscle activity according to the load for all muscles in the eccentric and concentric phases (p < 0.05), indicating that muscle activity increased as the load increased. In addition, in the comparison between HBBS and LBBS, significant differences were shown in all lower extremity muscles and all trunk muscles except for the external oblique in the concentric phase according to the bar position (p < 0.05). HBBS showed a higher muscle activity of the lower extremity in the eccentric and concentric phases than in LBBS, while LBBS showed a higher muscle activity of the trunk muscle in the eccentric and concentric phases than in HBBS (p < 0.05). HBBS requires more force in the lower extremity than LBBS and is particularly advantageous in strengthening the muscular strength of the quadriceps. In contrast, LBBS requires more muscle activity in the trunk than HBBS and is more effective in carrying heavier loads because of the advantage of body stability. This study suggests that rehabilitation experts apply the bar position and load as important variables affecting the intensity and method of training for target muscle strengthening of the lower extremities and trunk.

힙 힌지 동작에 따른 둥근 어깨와 정상인의 근활성도 비교

This study applied Hip hinge movement, a pelvic activation exercise, to round shoulder subjects and normal people based on the theory of the Anatomy train that our bodies are connected by kinesthetic chains and was executed to explore and compare muscle activity changes of the selected two groups during hip hinge movements. It was classified as round shoulder(n=9) and normal(n=9) for healthy young men in their 20s. The standard for selecting round shoulders at this point was to measure the height of the back of the shoulder bone peak from the side of the table and if the height is a ＜2.5㎝ or more, it is selected as round shoulders. The movement is to hold a rod fastening it at the back of the head, thoracic vertebrae and coccyx, then push the hips back by retracting the hip joint and get up. It is performed 15 times in a set alternating between the two sides.<BR> The results of this work show that when performing hip hinge movement, the Pectoralis major from the round shoulder group differ significantly in the left Pectoralis major(p＜.05) when the left arm is raised and showed no significant difference in muscle activity of the Deltoid posterior, Gluteus medius and Semitendinous also showed significant difference in muscle activity(p＜.05) and overall it was seen high in the round shoulder group. This produced a meaningful result in hip hinge exercises in some parts of round shoulder posture and this study is significant in suggesting different directions for future methods of exercise involving round shoulders.