Trapezius Muscle Activity Research Articles

The acute effects of vibratory stimuli during exercise on the sensorimotor control of the shoulder complex: A pilot study.

Functional stability of the shoulder requires a balance of active forces, passive forces, and control subsystems of the joint complex. Although whole-body vibration enhances shoulder muscle function and proprioception, the impact of vibration on the sensorimotor control of the shoulder joint remains unclear. To investigate the acute effect of vibratory stimuli on the sensorimotor control of the shoulder joint. Fifteen male participants (age, 22.7 ± 2.3years) were included and performed the exercise in a modified push-up position with partial weight-bearing on a vibration platform with and without vibratory stimuli. The vibration protocol included six sets lasting for 30s each with a 30-s rest between sets. The main outcome measures included the upper limb static stability test, Upper Quarter Y Balance Test (UQYBT), and electromyography data of the upper limb. Vibratory stimuli resulted in an increased UQYBT score (all directions; P< 0.01) and infraspinatus, serratus anterior, and lower trapezius muscle activity (P< 0.05) between pre- and post-exercise versus the control condition. Stabilometric parameters showed no significant interaction between condition and time. Vibratory stimuli could maximize training benefits while limiting injury risk for athletes. Our findings could guide the development of rehabilitation programs for patients with shoulder instability.

Muscle responses during radial nerve-biased upper limb neurodynamic test in asymptomatic individuals: a cross-sectional study

ABSTRACT This laboratory cross-sectional study aimed at explore the muscle response (MR) of the upper trapezius, infraspinatus, biceps brachii and extensor carpi radialis brevis (ECRB) during the radial nerve-biased upper limb neurodynamic test (RN-ULNT) in healthy participants. Myoelectric activity was stage-by-stage recorded during two sequencing variants of the RN-ULNT: S1, in which elbow extension was the last movement; and S2, in which wrist flexion was the last movement. Final elbow and wrist joint angle and sensory response (SR) in five zones (Z1-Z5) were also registered. MR was qualitatively categorized as ‘absent’ (No-MR), ‘true’ (TMR) or ‘uneven’ (UMR). In both sequences, significant increases in muscle activity occurred mostly during shoulder abduction and elbow extension (p ≤ 0.009). Also, elbow extension but not wrist flexion increased the activity of the ECRB muscle (p ≤ 0.009). S2 showed significantly higher upper trapezius (p = 0.04) and biceps brachii (p = 0.036) muscle activity during wrist flexion, and higher report of SR in Z1 and Z4 (p < 0.001) compared to S1. Only the ECRB muscle showed significant differences in the MR type between S1 and S2 (TMR, p = 0.016; UMR, = 0,012). Our results may be useful in the assessment of upper limb musculoskeletal disorders.

Effect of Trunk Position on Trapezius Muscle Activity and Ratio during Performing Modified Seated Cable Row Exercise

Background Changes in trunk angle as part of modifying the seated cable row exercise (MSCRE) are associated with trapezius muscle activity and ratio. Purpose This study aimed to determine the changes in muscle activity and ratio for the upper trapezius (UT), middle trapezius (MT), and lower trapezius (LT) muscles during the MSCRE in healthy participants without shoulder pain. Study design Cross-sectional study Methods We included participants who were 23 healthy individuals aged 23–39 years. The participants performed a pulling motion three times during the MSCRE at each of the following trunk angles: upright posture 0°, forward lean 30°, and backward lean 20°. Surface electromyography was performed for the UT, MT, and LT muscles during the 5-s isometric contraction, with the participant in a preset position, while the muscle activity was normalized with the maximal voluntary isometric contraction using the manual muscle test. Results The UT and LT muscle activities showed significant differences in angle (<italic>p</italic>&lt;0.05); the highest muscle activity was observed for the UT at backward lean 20° and LT at forward lean 30°. The UT/MT and UT/LT ratios showed significant differences in angle (<italic>p</italic>&lt;0.05), with the highest values observed at backward lean 20° for both the ratios. Conclusions These results suggest that the forward lean 30° trunk angle was most suitable for the MSCRE in the selective strengthening of the LT muscle, indicating that the trunk should be tilted forward during exercise for normal and balanced recovery of trapezius muscle activities in shoulder rehabilitation.

Surgeons’ physical workload in open surgery versus robot-assisted surgery and nonsurgical tasks

BackgroundMusculoskeletal disorders (MSDs) are common among surgeons, and its prevalence varies among surgical modalities. There are conflicting results concerning the correlation between adverse work exposures and MSD prevalence in different surgical modalities. The progress of rationalization in health care may lead to job intensification for surgeons, but the literature is scarce regarding to what extent such intensification influences the physical workload in surgery. The objectives of this study were to quantify the physical workload in open surgery and compare it to that in (1) nonsurgical tasks and (2) two surgeon roles in robot-assisted surgery (RAS).MethodsThe physical workload of 22 surgeons (12 performing open surgery and 10 RAS) was measured during surgical workdays, which includes trapezius muscle activity from electromyography, and posture and movement of the head, upper arms and trunk from inertial measurement units. The physical workload of surgeons in open surgery was compared to that in nonsurgical tasks, and to the chief and assistant surgeons in RAS, and to the corresponding proposed action levels. Mixed-effects models were used to analyze the differences.ResultsOpen surgery constituted more than half of a surgical workday. It was associated with more awkward postures of the head and trunk than nonsurgical tasks. It was also associated with higher trapezius muscle activity levels, less muscle rest time and a higher proportion of sustained low muscle activity than nonsurgical tasks and the two roles in RAS. The head inclination and trapezius activity in open surgery exceeded the proposed action levels.ConclusionsThe physical workload of surgeons in open surgery, which exceeded the proposed action levels, was higher than that in RAS and that in nonsurgical tasks. Demands of increased operation time may result in higher physical workload for open surgeons, which poses an increased risk of MSDs. Risk-reducing measures are, therefore, needed.

Use of wearable physiological sensors to predict cognitive workload in a visuospatial learning task.

Increased cognitive workload, sometimes known as mental strain or mental effort, has been associated with reduced performance. The use of physiological monitoring was investigated to predict cognitive workload and performance. Twenty-one participants completed a 10-minute seated rest, a visuospatial learning task modeled after crane operation, and the Stroop test, an assessment that measures cognitive interference. Heart rate, heart rate variability, electrodermal activity, skin temperature, and electromyographic activity were collected. It was found that participants' ability to learn the simulated crane operation task was inversely correlated with self-reported frustration. Significant changes were also found in physiological metrics in the simulation with respect to rest, including an increase in heart rate, electrodermal activity, and trapezius muscle activity; heart rate and muscle activity were also correlated with simulation performance. The relationship between physiological measures and self-reported workload was modeled and it was found that muscle activity and high frequency power, a measure of heart rate variability, were significantly associated with the workload reported. The findings support the use of physiological monitoring to inform real time decision making (e.g., identifying individuals at risk of injury) or training decisions (e.g., by identifying individuals that may benefit from additional training even when no errors are observed).

Improvements in hand functions and changes in proximal muscle activities in myoelectric prosthetic hand users at home: a case series.

Adaptation in proximal muscles for daily motor tasks after sustained use of a prosthetic hand has not been fully understood. This study aimed to investigate changes in hand functions and activities of proximal muscles after multiple weeks of using a myoelectric prosthetic hand at home. Repeated measures. Four people with traumatic upper-limb loss used a myoelectric prosthetic hand (bebionic) at home over the 6- to 8-week period. A user survey, Orthotics and Prosthetics User Survey for Upper Extremity Functional Status 2.0, was used to measure upper-limb functions and the degree of using the prosthetic hand each week. Their hand functions, muscle activities, and grip-specific neuromuscular effort were evaluated by the Southampton Hand Assessment Procedure at the preassessment and postassessment sessions (PRE and POST, respectively). All subjects increased Southampton Hand Assessment Procedure scores at PRE compared with POST with subject-specific changes in muscle activations. In a detail, at POST, subject 1 reduced the shoulder muscle activity compared with PRE, while at POST, subject 2 reduced biceps activity compared with PRE. At POST, greater pectoralis activity and reduced trapezius activity were observed in subject 3, and greater activity in those two muscles was found in subject 4 compared with PRE. After multiple weeks of using the myoelectric prosthetic hands, their hand functions during ADL tasks were improved and changes in the muscle activities were found.

A comparison of muscle activity, posture and body discomfort during the use of different computer screen sizes

This study aims to compare changes in neck angles, muscle activities, ergonomic risk and body discomfort caused by use of two different computer screen sizes. The 36 female users who participated used displays with 46.99 and 58.42-cm screen sizes and were assessed for craniocervical angle (CCA), craniovertebral angle (CVA), upper trapezius (UT) and sternocleidomastoid (SCM) muscle activity, ergonomic risk and body discomfort for a duration of 1 h. The results showed there were no significant differences when comparing usage between both computer screen sizes (p > 0.05). However, there were significant differences in the CCA, UT muscle activity and body discomfort when comparing before and after usage for both computer screen sizes (p < 0.05). The results indicate that computer users can select different screen sizes for working but should be concerned with neck angle, muscle activity and body discomfort when using for long periods of time.

Corrective exercises administered online vs at the workplace for pain and function in the office workers with upper crossed syndrome: randomized controlled trial.

ObjectiveTo evaluate the effects of online-supervised versus workplace corrective exercises on neck–shoulder pain (NSP), sick leave, posture, workability, and muscular activity among office workers with the upper crossed syndrome (UCS).MethodsWe performed a parallel-group randomized control trial at Shahid Beheshti University, Tehran, Iran, assigning 36 office workers to online-supervised, workplace, and control groups (mean (SD) age 38.91 ± 3.87, 38.58 ± 7.34, 37.00 ± 8.12). Inclusion criteria were alignment alteration (forward head (≥ 45°), rounding shoulder (≥ 52°), rounding back (≥ 42°), and pain intensity ≥ 3 in neck and shoulder. The two intervention groups performed 8-week exercise program, while the control group continued usual activities. Primary (NSP and sick leave) and secondary outcomes [postural angles, workability, and muscular activity were measured by VAS, outcome evaluation questionnaire (OEQ), photogrammetry, workability index, and EMG, respectively, at the baseline and an 8-week follow-up].ResultsANCOVA results revealed improvements for the online-supervised group versus control for NSP (P = 0.007), postural angles (P = 0.000, P = 0.001, P = 0.005), workability (P = 0.048, P = 0.042), and upper trapezius activation (P = 0.024, P = 0.016), respectively. Using paired t tests, both intervention groups improved from baseline to follow-up for NSP (P = 0.000, P = 0.002), forward head posture (P = 0.000, P = 0.000), round shoulders (P = 0.001, P = 0.031), and round back (P = 0.034, P = 0.008), respectively. Related parameters of workability (P = 0.041, P = 0.038), upper trapezius (P = 0.005, P = 0.005, P = 0.022), and serratus anterior (P = 0.020, P = 0.015) changed only in the online-supervised group.ConclusionOnline-supervised corrective exercise seems to improve a range of parameters related to work performance. These findings are highly applicable in light of the ongoing COVID pandemic; many workers have to work from home.

Pain and electromyography reduction cause of sitting upright posture, frequent break, eye rest and self-stretching during smartphone usage.

Prolonged use of the smartphone causes neck and shoulder pain. However, no study has yet evaluated the effects of sitting upright, combined with frequent breaks, eye rest and self-stretching on pain and EMG during smartphone use. The purpose of the study was to compare pain and muscle activity between the control group (rest only) and the intervention group (rest combined with correct posture, eye rest and self-stretching) in smartphone use for 41.30 minutes. Forty-four healthy females aged 18-25 years old were recruited and randomly divided into two groups. The body pain chart and Visual Analog Scale (VAS) were used to evaluate pain. Electromyography (EMG) was used to measure muscle activity of Cervical Erector Spinae (CES) and Upper Trapezius (UT) muscles. The results showed that overall pain and neck pain in the control group increased significantly after smartphone use for 20 min and continually increased to 41.30 minutes (p < 0.05). Overall pain and neck pain in the intervention group was significantly lesser than control group after smartphone use for 41.30 minutes (p < 0.05). In the control group, EMG of CES at 41.30 minute was significantly higher than that of at 0 min (p < 0.05). There was no significant difference in EMG of UT between the two groups. Conclusion smartphone user in the interventional group reported less pain when compared to control group after Smartphone use for 41.30 minutes. Therefore, the user aged 18-25 years should have a rest combined with correct posture, eye rest and self-stretching to prevent neck pain during prolonged smartphone use.

Effects of Rehearsal Time and Repertoire Speed on Upper Trapezius Activity in Conservatory Piano Students.

Repetitive piano play may overload neck and shoulder muscles and tendons, leading to playing-related musculoskeletal disorders (PRMDs). In this pilot study (EMG data of the extensor carpi radialis have been published separately), surface electromyography (sEMG) activity of the upper trapezius (UT) was captured in 10 conservatory piano students while playing a fast and a slow music score selected from the individual's repertoire, each 3 minutes long. Measurements were made at baseline and again after 2 hrs and 4 hrs of rehearsal time of the piano études. The amplitude of the sEMG signal was processed by a smoothing algorithm, and the frequency component with a non-orthogonal wavelets procedure. Amplitude of the sEMG was expressed in percent of maximal voluntary contraction (%MVC) at baseline, and the frequency component using median frequency based on the frequency band powers. Statistical analysis encompassed repeated measures ANOVAs for the amplitude and frequency components of the sEMG signal (set at 5%). The students also rated the intensity of rehearsals using a visual analog scale (VAS). The median values for the %MVC presented a global mean for the left trapezius of 5.86 (CI90% 4.71, 6.97) and 5.83 for the right trapezius (CI90% 4.64, 7.05). The rehearsals at moderate intensity increased the amplitude of %MVC of the upper trapezius by around 50% and decreased the median frequency. Playing faster presented higher magnitudes of activity of the upper trapezius. The decrease in the median frequency in response to long rehearsals may be a sign of muscle fatigue.

Muscle activity alternations in preadolescent swimmers with shoulder pain

Background. Shoulder pain is the most often declared musculoskeletal injury among swimmers. It evolves due to overuse injuries and/or functional disorders, which may result from neuromuscular control deficits. The aim of this study was to check the epidemiology of shoulder pain in preadolescent swimmers and to check the muscle activity of serratus anterior and upper trapezius muscles comparing two groups of athletes. Material and methods. 22 swimmers from one team were divided in two groups: those with the history of shoulder pain and those without any previous syndromes. After functional examination of the shoulder region, we performed surface electromyography examination during the shoulder flexion in scapular plane. Results. 27% of the whole group reported at least one episode of shoulder pain. Con­cerning electromyography examination, we observed increased serratus anterior activity in symptomatic group (p-value=0,0245) Conclusions. 1. Preadolescent swimmers aged 10-14 present previous episodes of the shoulder pain but its prevalence is lesser comparing to the adult athletes. 2. Previous pain episodes may alter the electromyographic recording and may be considered as a protective mechanism but they can also change the shoulder mechanics.

Comparison of the Lower Trapezius Muscle Activity during Three Different Shoulder Flexion Exercises in Healthy Subjects

Comparison of the Lower Trapezius Muscle Activity during Three Different Shoulder Flexion Exercises in Healthy Subjects

Using biofeedback to optimize scapular muscle activation ratios during a seated resisted scaption exercise

Impairments in muscle activation have been linked to increased risk of developing shoulder pathologies such as subacromial impingement syndrome (SIS) and associated rotator cuff injuries. Individuals with SIS have demonstrated increased upper trapezius (UT) muscle activation and reduced serratus anterior (SA) and lower trapezius (LT) muscle activation, which can be collectively represented as ratios (UT/SA and UT/LT). Targeted exercise is an important component of shoulder rehabilitation programs to re-establish optimal muscle activation and ratios. Electromyography (EMG) biofeedback during exercise has been shown to reduce UT activation and favorably alter scapular muscle activation ratios, however, a literature gap exists regarding the efficacy of other types of biofeedback. Therefore, we compared the effects of three types of biofeedback (visual EMG, auditory, verbal cues) on UT/SA and UT/LT ratios during a seated resisted scaption exercise in fifteen subjects without shoulder pain. Baseline muscle activation was recorded and compared to real-time muscle activation during each randomized biofeedback trial. All biofeedback types showed improvements in the UT/SA and UT/LT ratios, with visual EMG demonstrating a significant change in UT/LT ratio (p < 0.05). These results suggest that biofeedback could be utilized as a component of rehabilitation programs to prevent or treat shoulder pain.

Chronic Adaptations of Shoulder Muscle Synergies in Healthy Baseball Players.

Previous research has demonstrated that muscle synergy structure can adapt owing to training and injury; however, muscle synergies have not been evaluated in baseball players. The throwing arm would have a similar muscle synergy structure but different levels of individual muscle activity within each synergy, relative to the nonthrowing arm. Cross-sectional study in a controlled laboratory setting. Fourteen healthy competitive baseball players were included. Participants were tested bilaterally during a center-out planar reaching task using the KINARM robot, where kinematic data and surface electromyography data from 14 glenohumeral and scapular muscles were synchronized. Principal component analysis was used to extract muscle synergies, the variance accounted for (VAF) of each synergy, and individual muscle coefficients. The dominant (DOM) arm was compared with the nondominant (NDOM) arm using paired t tests for all dependent variables. The same number of muscle synergies were extracted on the DOM and NDOM arms, along with no differences in VAF. In the first synergy, the infraspinatus (DOM 0.798 vs NDOM 0.587, P = 0.038) and lower trapezius (DOM 0.872 vs NDOM 0.480, P = 0.005) muscle coefficients significantly increased on the DOM arm. The second synergy had a significantly increased anterior deltoid (DOM 0.764 vs NDOM 0.374, P = 0.003) and a significantly decreased posterior deltoid (DOM -0.069 vs NDOM 0.197, P = 0.041) muscle coefficient on the DOM arm. The DOM shoulder exhibits a higher proportion of infraspinatus and lower trapezius muscle activation during the external rotation and abduction synergy. Also, the DOM shoulder has increased muscle activation of the teres major and latissimus dorsi during the internal rotation synergy, and increased muscle activation of the pectoralis major during the cross-body adduction synergy, compared with the NDOM shoulder. By exploring these neuromuscular adaptations, the improved understanding of muscle synergy adaptations in baseball players will help optimize injury prevention and rehabilitation techniques.

Bending the Elbow During Shoulder Flexion Facilitates Greater Scapular Upward Rotation and a More Favorable Scapular Muscle Activation Pattern

Decreased scapular upward rotation (UR) and diminished activation of the serratus anterior (SA) and lower trapezius (LT) are often observed among patients with subacromial impingement syndrome. Maintaining the elbow fully flexed during shoulder flexion may limit glenohumeral motion due to passive insufficiency of the triceps brachii and therefore facilitate greater scapular UR and increased scapular muscle activation. To compare scapular UR, SA, upper trapezius (UT), middle trapezius, and LT activation levels between shoulder flexion with the elbow extended (Flexion-EE) to shoulder flexion with the elbow fully flexed (Flexion-EF). This study hypothesized that Flexion-EF would result in greater scapular UR, greater SA and LT activation, and a lower UT/SA and UT/LT activation ratio compared with Flexion-EE. Cross-sectional study. A clinical biomechanics laboratory. Twenty-two healthy individuals. Scapular UR and electromyography signal of the SA, UT, middle trapezius, and LT, as well as UT/SA and UT/LT activation ratio were measured during Flexion-EE and Flexion-EF. Flexion-EF resulted in greater scapular UR compared with Flexion-EE (P < .001). Flexion-EF resulted in greater SA activation, lower UT activation, and a lower UT/SA activation ratio compared with Flexion-EE (P < .001). Fully flexing the elbow during shoulder flexion leads to increased scapular UR primarily through greater activation of the SA. This exercise may be of value in circumstances involving diminished scapular UR, decreased activation of the SA, and an overly active UT such as among patients with subacromial impingement syndrome.

Supine scapular punch: An exercise for early phases of shoulder rehabilitation?

BackgroundSerratus anterior strengthening generally appears in shoulder rehabilitation protocols. This study's aim was to measure electromyographic activity of the serratus anterior, upper trapezius, and infraspinatus muscles during the Supine Scapular Punch exercise in healthy volunteers and those with unilateral shoulder pain. MethodsFifty-four participants were included and grouped as without (n = 34, age = 25.8 years) or with unilateral shoulder pain (n = 20, age = 26.3 years, visual analogue scale = 4.15 cm). Electromyographic activity of the serratus anterior, upper trapezius, and infraspinatus muscles was assessed during Supine Scapular Punch (four phases: P1 = press up concentric, P2 = Supine Scapular Punch concentric, P3 = Supine Scapular Punch eccentric, P4 = press up eccentric) performed under two conditions, with and without additional load. FindingsOverall muscle activity during P1 and P4 was negligible (< 10% maximal voluntary isometric contractions). During P2 and P3, no statistically significant differences in serratus anterior and upper trapezius muscle activity were found between groups, with moderate to high serratus anterior activity (28.94% to 44.3%) and very low upper trapezius activity (< 6%). Upper trapezius/serratus anterior activity ratios ranged from 0.09 to 0.18. Overall infraspinatus muscle activity was always very low (< 10%). InterpretationThe Supine Scapular Punch induces moderate to high serratus anterior muscle activity with very low upper trapezius and infraspinatus activation. Based on these results, the Supine Scapular Punch is a safe exercise that can be used in the early phases of shoulder rehabilitation.

Does verbal and tactile feedback change EMG activity in shoulder girdle and trunk muscles during plyometric exercise in overhead athletes with and without shoulder pain?

ObjectivesTo investigate if there is a difference in muscle activity for overhead athletes before and after an intervention with correction of both core and scapula compared to no intervention and is there a difference between overhead athletes with or without shoulder pain. DesignControlled laboratory EMG study including intervention. SettingUniversity EMG laboratory. ParticipantsSixty overhead athletes, 30 with shoulder pain and 30 healthy controls were included performing plyometric rotational shoulder exercise. Main outcomesHalf of the participants received an intervention the other half were controls with no intervention. EMG muscle activity from 10 scapular, thoraco-humeral and trunk muscles were measured. ResultsThere were no significant differences in muscle activation levels between the groups with or without intervention. For the shoulder pain group, there were significant lower activity in Upper Trapezius when repeating the exercise. The shoulder pain group had significant higher activity in Pectoralis Major compared to the Healthy Control group. ConclusionsMost differences were found between the pre- and post-test. Repetition of the exercise seems to be more important than verbal and tactile instructions. Comparing the shoulder pain group with the healthy controls confirms previous findings that, pain patients recruit muscles differently from healthy persons.

Function, strength, and muscle activation of the shoulder complex in Crossfit practitioners with and without pain: a cross-sectional observational study

BackgroundThe shoulder joint is the most commonly injured joint in CrossFit practitioners, because of the high intensity and loads associated with this sport. Despite the large number of clinical cases, there is a shortage of studies that investigate influence of biomechanical aspects of upper limbs' injuries on CrossFit practitioners. This study hypothesized that there would be a difference in function, strength, and muscle activation between Crossfit practitioners with and without shoulder pain.MethodsWe divided 79 Crossfit practitioners into two groups according to whether they reported pain (n = 29) or no pain (n = 50) in the shoulder during Crossfit training. Muscle function, strength, and activation were assessed using the Disability Arm, Shoulder and Hand function questionnaire, Upper Quarter Y Balance Test and Closed Kinetic Chain Upper Extremity Stability Test shoulder tests, isometric muscle strength assessment by manual dynamometry and muscle activation by surface electromyography and pain report.ResultsThe function based on questionnaire was associated with pain (p = 0.004). We observed a statistically significant difference between the two groups only in the surface electromyography activity of the lower trapezius, and in the variables of shoulder pain and function (p = 0.038).ConclusionCrossfit practitioners with shoulder pain occurring during training showed good function and stability of the shoulder joint, but there was a reduction in the activation of stabilizing muscles, especially the lower trapezius.Trial registration Registro Brasileiro de Ensaios Clinico (Brasilian National Registry) with the ID: RBR-2gycyv.

The Influence of Idiopathic Chronic Neck Pain on Sternocleidomastoid and Upper Trapezius Muscle Activity and Elasticity

The Influence of Idiopathic Chronic Neck Pain on Sternocleidomastoid and Upper Trapezius Muscle Activity and Elasticity

젊은 성인의 백팩과 숄더백 착용에 따른 위등세모근, 척추세움근의 근활성도 비교

The purpose of this study was to find out how each bag affects the muscle activity of the upper trapezius and erector spinae muscles when walking with a backpack and a shoulder bag. The study subjects were 25, and 17 males and 8 females were recruited. After walking from the 1st to the 6th floor with a backpack and a shoulder bag weighing 10% of the person's weight, walking 10m marked on the laboratory floor was performed. Surface electromyography was used to determine the muscle activity of both dorsal and vertebral pectoral muscles, and a pain sensor was used to determine the degree of pain. With PASW 18, the paired sample t test and one-way analysis of variance were used, and the Bonferroni correction was used for the post-test. There was a significant difference in the activity of the left and right muscles of the upper trapezius when wearing a shoulder bag and the difference in activity of the left and right muscles of the upper trapezius without wearing a bag. When worn, there was also a significant difference in the activity of the left and right muscles of the upper trapezius. There was no significant difference in the activity of the left and right muscles of the erector spinae muscle when the bag was not worn, and when the backpack and shoulder bag were worn. In addition, the erector spinae muscle showed consistently high muscle activity, unlike the upper trapezius, which means continuous muscle contraction of the erector spinae, which is a factor that can increase muscle fatigue. Therefore, it should be strengthened with a focus on the erect vertebrae rather than the upper trapezius. The results of this study inform those who wear shoulder bags that shoulder bags cause an imbalance in muscle activity of the upper trapezius muscle and may cause musculoskeletal problems. It is recommended to wear a backpack rather than a shoulder bag, and it will help to prevent the imbalance of the body.