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Forward head posture (FHP) is a serious problem causing head and neck disability, but the characteristics of muscle activity during long-term postural maintenance are unclear. This study aimed to investigate a comparison of electromyography (EMG) activation properties and subjective fatigue between young adults with and without habitual FHP. In this study, we examined the changes in the spatial and temporal distribution patterns of muscle activity using high-density surface EMG (HD-SEMG) in addition to mean frequency, a conventional measure of muscle fatigue. Nineteen male participants were included in the study (FHP group (n = 9; age = 22.3 ± 1.5 years) and normal group (n = 10; age = 22.5 ± 1.4 years)). Participants held three head positions (e.g., forward, backward, and neutral positions) for a total of 30 min each, and the EMG activity of the trapezius pars descendens muscle during posture maintenance was measured by HD-SEMG. The root mean square (RMS), the modified entropy, and the correlation coefficient were calculated. Additionally, the visual analogue scale (VAS) was evaluated to assess subjective fatigue. The RMS, VAS, modified entropy, and correlation coefficients were significantly higher in the FHP group than in the normal group ( p  < 0.001). With increasing postural maintenance time, the modified entropy and correlation coefficient values significantly decreased, and the mean frequency and VAS values significantly increased ( p  < 0.001). Furthermore, the forward position had significantly higher RMS, correlation coefficient, modified entropy, and VAS values than in the neutral position ( p  < 0.001). The HD-SEMG potential distribution patterns in the FHP group showed less heterogeneity and greater muscle activity in the entire muscle and subjective fatigue than those in the normal group. Excess muscle activity even in the neutral/comfortable position in the FHP group could potentially be a mechanism of neuromuscular conditions in this population.

The anatomical connection between latissimus dorsi (LD), thoracolumbar fascia, and contralateral gluteus maximus (GM) enables myofascial force transmission (MFT) between the shoulder, trunk, and hip. This study investigates whether regular sports practice, specifically running, influences this MFT pathway. Given the potential changes in tissue stiffness from sports practice and the importance of this property for MFT, we hypothesize that runners may exhibit greater MFT between the LD and GM, resulting in altered passive properties of the lumbar and hip regions during LD contraction. This study aimed to investigate whether runners present a higher modification in lumbar stiffness and passive properties of the contralateral hip due to LD contraction than sedentary individuals. The lumbar stiffness, hip resting position, passive hip torque, and stiffness of fifty-four individuals were assessed using an indentometer and an isokinetic dynamometer, respectively, in two conditions: LD relaxed, and LD contracted. The main and interaction effects were assessed using a two-way ANOVA. The LD contraction increased lumbar stiffness (p < 0.001; ηp2 = 0.50), externally rotated the hip resting position and increased the passive hip torque and stiffness (p < 0.05; ηp2 > 0.1) in both groups. In addition, runners presented higher lumbar stiffness compared to sedentary in the LD contracted condition (p = 0.017, ESd = 0.54). Although runners exhibited increased lumbar stiffness during LD contraction, the MFT from the shoulder to the hip joint occurred similarly in both groups.

PurposeNeck and upper-back stiffness is encountered in daily life, with symptoms appearing as dullness or aches predominantly in the trapezius muscle (TM). Our previous study demonstrated that TM hardness as measured with a muscle hardness meter correlates well with transverse cervical artery (TCA) flow supplying the TM. Muscle hardness meters, however, cannot measure hardness in the TM alone. Meanwhile, recent advances in ultrasound elastography have enabled the evaluation of localized hardness in targeted tissues. The present study, therefore, aimed to clarify the relationship between TM hardness as measured by elastography and TCA hemodynamics as measured on Doppler sonography, with reference to daily symptoms of upper-back stiffness.MethodsThe study population comprised 66 healthy young adults (32 males, 34 females; mean age, 21 ± 1 years). Relationships were evaluated between TM hardness as a negative correlate of strain ratio from elastography and TCA hemodynamics on Doppler sonography. Hemodynamics in the TCA were evaluated according to the frequency of neck and upper-back stiffness.ResultsTM strain ratio correlated with peak systolic velocity (PSV) in the TCA (r = 0.273, p = 0.036), particularly in symptomatic subjects (r = 0.417, p = 0.022). PSV in the TCA decreased with increasing frequency of daily symptoms (p = 0.045).ConclusionTCA hemodynamics correlated with muscle hardness when evaluating localized TM hardness. This relationship and low PSV in the TCA were evident in symptomatic subjects. These results suggest that PSV in the TCA is associated with neck and upper-back stiffness.

Workers are driven to work faster in the industrial work environment to meet high productivity targets. An increased work pace leads to increased muscle activation. However, the effect of work pace on bilateral upper trapezius muscles during sewing machine operation in an industrial work environment has not been thoroughly investigated in experimental studies. Therefore, this research aims to conduct an experimental study to analyze the bilateral upper trapezius muscle activity of industrial sewing machine operators at different levels of work pace. Thirty subjects (15 males, and 15 females) continuously performed the sewing operation for two hours in an industrial work environment. Experiments were conducted for two levels of work pace i.e. low pace (100% of standard cycle time) and high pace (120% of standard cycle time). Electromyographic signals were recorded from the bilateral upper trapezius muscles. The EMG amplitude (RMS) among the muscles was computed. A statistically significant ( p  < 0.05) increase in muscle activity was observed with an increased work pace. In this study, right upper trapezius muscle activity increased by 30.4% during high work pace tasks compared to low pace, while the left upper trapezius showed a 24.12% increase. The right upper trapezius showed a mean difference of 0.696 (%MVC), and the left upper trapezius showed 0.399 (%MVC), both indicating greater activity during high-pace tasks. The increase in muscle activity with time indicated the presence of muscle fatigue among sewing machine operators. Furthermore, higher muscular activity was observed among females than males. This research highlights the critical need to balance productivity goals with the health and safety of workers, reducing the risk of muscle fatigue and associated work-related musculoskeletal disorders.

Neck pain (NP), neck injuries, and concussions are more prevalent in female athletes than in their male counterparts. Females exhibit less neck girth, strength, and stiffness against a perturbation. As part of the clinical examination for individuals with NP, ultrasound (US)-based imaging of the cervical muscles has become common. Muscle size or thickness and stiffness can be measured with US-based B-mode and shear-wave elastography (SWE), respectively. Information on reliability, normative values, and sex differences based on US-based muscle size or thickness and stiffness in young and athletic individuals is limited. To evaluate sex differences in US-based muscle size or thickness and biomechanical properties of the cervical-flexor and -extensor muscles. Cross-sectional study. Laboratory. A total of 13 women (age = 23.7 ± 1.9 years, height = 167.1 ± 6.1 cm, mass = 63.8 ± 5.6 kg) and 11 men (age = 25.6 ± 4.9 years, height = 178.7 ± 8.3 cm, mass = 78.9 ± 12.0 kg). The same examiner collected all measures, using US B-mode to scan the cross-sectional area and thickness of the longus colli (LC), sternocleidomastoid (SCM), cervical-extensor muscles, and upper trapezius (UT) muscle. The US SWE-mode was used to measure the stiffness of the SCM and UT. Independent tests or Mann-Whitney tests were calculated to determine sex differences. The intraclass correlation coefficient (ICC) measured intrarater test-retest reliability. Men had thicker SCMs than women ( = .01). No sex differences were present for longus colli cross-sectional area, cervical-extensor muscle thickness, or UT thickness ( > .05). In addition, no sex differences were evident for SCM ( = .302) or UT ( = .703) SWE stiffness. Reliability was good to excellent (ICC = 0.715-0.890) except for SCM SWE stiffness (ICC = 0.554). The only sex difference was in SCM thickness. However, smaller SCMs in women did not result in less SCM SWE stiffness. We provided normative values for US-based imaging of the cervical-flexor and -extensor muscles in young and athletic men and women.

OBJECTIVES: Sustained activity of the upper trapezius muscle during work has been linked to the development of neck pain. Women have higher occurrences of neck pain than men, even in the same occupations. This study aimed to investigate sex-specific associations between upper trapezius muscle activity time-related variables and neck pain using a meta-analysis of pooled data. METHODS: Seven Scandinavian research institutes provided surface electromyographic (EMG) data on the upper trapezius muscle activity during work and related questionnaire-based data on neck pain severity. EMG and questionnaire data were harmonized and pooled. Associations between upper trapezius muscle activity variables [median muscle activity, frequency of muscular rest periods, and periods with sustained muscle activity (SUMA)] and neck pain severity were investigated separately for women (N=293) and men (N=418) using linear regression analyses. RESULTS: In the cross-sectional analyses, women showed significant positive associations between the number of short SUMA periods and negative associations for long SUMA periods in regard to neck pain severity. In the longitudinal analyses, women showed no significant associations. In the cross-sectional analysis for men, one significant positive association was found between median upper trapezius muscle activity and neck pain severity. CONCLUSIONS: Compared to men, neck pain severity among women appears to be more dependent on upper trapezius muscle activity patterns at work. Therefore, ergonomic and organizational recommendations for work should be sex-specific or adjusted for women to reduce their prevalence of neck pain. Further research is needed to elucidate the underlying mechanisms of these sex differences.

BackgroundSeroma formation is a common complication after mastectomy. This review aims to elucidate which surgical techniques are most effective in reducing the dead space and therefore seroma formation in patients undergoing mastectomy.MethodsA literature search was performed to identify clinical studies comparing any form of flap fixation to conventional closure technique in patients undergoing mastectomy with or without axillary clearance. Studies were eligible for inclusion if outcome was described in terms of seroma formation and/or complications of seroma formation. Studies on animal research or breast reconstruction with tissue expanders or flap harvesting (latissimus dorsi) were excluded.ResultsA total of nine articles were eligible for inclusion. Five were retrospective studies and four were prospective. Retrospective and prospective studies have demonstrated the higher incidence of seroma formation in patients not undergoing mechanical flap fixation. The incidence of seroma-related complications in these studies vary. Four out of the nine studies demonstrate that patients undergoing flap fixation, need significantly fewer seroma aspirations. There are very few studies on the use of tissue glues preventing seroma formation.ConclusionThe scientific body of evidence favoring flap fixation after mastectomy is convincing. Mechanical flap fixation seems to reduce seroma formation and seroma aspiration after mastectomy. There are, however, no well-powered randomized controlled trials evaluating all aspects of seroma formation and its sequelae. Further research should elucidate whether flap fixation using sutures or tissue glue is superior.

The wall-slide exercise is commonly used in clinic and research settings. Theraband positioning variations for hip exercises have been investigated and used, but Theraband positioning variations for upper extremity wall-slide exercises, although not commonly used, have not been examined. To evaluate the effect of different Theraband positions (elbow and wrist) on the activation of the scapular and shoulder muscles in wall-slide exercises and compare these variations with each other and with regular wall-slide exercises for the upper limbs. Descriptive laboratory study. University laboratory. A total of 20 participants (age = 23.8 ± 3 years, height = 176.5 ± 8.14 cm, mass = 75.3 ± 12.03 kg, body mass index = 24.23 ± 4.03) with healthy shoulders. Participants performed wall-slide exercises (regular and 2 variations: Theraband at the elbow and Theraband at the wrist) in randomized order. Surface electromyographic activity of the trapezius (upper trapezius [UT], middle trapezius [MT], and lower trapezius [LT]), infraspinatus, middle deltoid (MD), and serratus anterior (SA) muscles. Regular wall-slide exercises elicited low activity in the MD and moderate activity in the SA muscles (32% of maximal voluntary isometric contraction [MVIC] in the SA), whereas the Theraband-at-elbow and Theraband-at-wrist variations elicited low activity in the MT, LT, infraspinatus, and MD muscles and moderate activity in the SA muscle (46% and 34% of MVIC in the SA, respectively). The UT activation was absent to minimal (classified as 0% to 15% of MVIC) in all wall-slide exercise variations. The Theraband-at-wrist variation produced lower UT:MT, UT:LT, and UT:SA levels compared with the regular wall-slide exercise and Theraband-at-elbow variation. In shoulder rehabilitation, clinicians desiring to activate the scapular stabilization muscles should consider using the Theraband-at-wrist variation. Those seeking more shoulder-abduction activation and less scapular stabilization should consider using the Theraband-at-elbow variation of the upper extremity wall-slide exercise.

To compare the seated flexion strength test (FST) with two modifications incorporating shoulder external rotation and supine positioning, aiming to improve serratus anterior (SA) selectivity through reduced upper (UT) and lower trapezius (LT) interference. Cross-sectional validation study using surface electromyography (EMG) and handheld dynamometry. University hospital musculoskeletal department. Eighteen healthy adults. EMG activation of SA, UT, LT and pectoralis major normalized to maximum voluntary contraction; activation ratios (UT/SA and LT/SA); force measurements with handheld dynamometer. Both modifications significantly reduced UT (p = 0.002) and LT activation (p = 0.010–0.049) compared to the FST without significantly reducing SA activity. The ratios (median UT/SA, LT/SA) showed a non-significant trend toward reduction in modification 1 (0.53, 0.57) and modification 2 (0.60, 0.41) compared to the FST (0.83, 0.71). Only modification 2 demonstrated excellent reliability (ICC 0.97, 95 % CI:0.92–0.99, MDC 14 %). The modification 2 (supine positioning, shoulder external rotation, 45° tilted dynamometer) enhances SA isolation and demonstrates superior reliability compared to the FST. Therefore, it may improve clinical assessment of SA strength particularly when differentiating from UT and LT is of interest. Further research is needed before applying these findings to patient populations. •High trapezius interference confirmed during flexion strength test.•Both modifications including external rotation and supine reduced trapezius EMG.•Excellent reliability in the modification applying a 45° tilted dynamometer.•Modified flexion strength test enhances validity for targeting serratus anterior.

Background and Objectives: Scapular muscles are crucial in controlling scapular movement, ensuring proper alignment, and preventing injuries during shoulder joint motion. The shoulder abduction angle is one of the most important factors when performing exercises to improve scapular movement control. The Pilates reformer arm work (AW) movement can be performed with different shoulder abduction angles. Therefore, this study analyzed the differences in scapular muscle activation depending on the shoulder abduction angle during the AW movement. Materials and Methods: Twenty-six healthy adult males performed the AW movement under four shoulder abduction angle conditions (0°, 90°, 135°, 160°). When performing the AW in the four conditions, surface electromyography analyzed the muscle activation of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), serratus anterior (SA), posterior deltoid (PD), and levator scapulae (LS), and the muscle activation ratios of the UT/LT, LS/LT, UT/SA, and LS/SA. Results: The UT, LT, and SA muscle activation increased proportionally with the increasing shoulder abduction angle (p < 0.001). The LT showed the highest muscle activity at the shoulder abduction angle of 135° (p < 0.001). The MT and PD showed the highest muscle activities at the shoulder abduction angle of 90° (p < 0.001). The muscle activity ratios of the UT/LT and LS/LT were the lowest at the shoulder abduction angles of 90° and 135° (p < 0.001). The muscle activity ratio between the UT/SA and LS/SA was the lowest at the 135° and 160° shoulder abduction angles (p < 0.001). Conclusions: Our findings highlight the impact of the shoulder abduction angle on scapular muscle activation, suggesting that different angles may be used to engage specific muscles during Pilates reformer arm work exercises selectively. This insight can guide exercise interventions for individuals aiming to improve their scapular control and stability.