Biceps Research Articles

Stiffness of elastic cuffs affects physiological and perceptual responses but not motor performance fatigue during low external load resistance exercise with practical blood flow restriction

ABSTRACT Practical blood flow restriction (pBFR), using non-pneumatic elastic cuffs, is a feasible and cost-effective alternative to pneumatic systems. There is evidence that cuff stiffness influences haemodynamic and perceptual responses in the upper body during rest. However, the impact of cuff stiffness during exercise is still unknown. Therefore, this study investigated the influence of cuff stiffness on physiological, perceptual, and performance changes during exercise. In a randomized and counterbalanced order, ten recreationally active males performed four sets of unilateral elbow flexions at 20% of individuals’ one-repetition-maximum with two elastic cuffs of different stiffness (low stiffness cuff [LS] and high stiffness cuff [HS]) each applied with two different overlaps (10% and 20% overlap in relation to the limb circumference) as well as a control condition without pBFR. Before and after exercise, maximal voluntary isometric contraction torque was measured to assess motor performance fatigue. During exercise, muscle oxygen saturation of the biceps brachii as well as effort and exercise-induced muscle pain perception were recorded. Statistical analysis revealed that motor performance fatigue was not different between conditions (BF10 = 0.289). The decline in muscle oxygen saturation (BF10 = 8.508 and BF10 = 1039.543) as well as effort (BF10 = 2646.104 and BF10 = 2.773∙106) and exercise-induced muscle pain perception (BF10 = 14087.983 and BF10 = 7.306∙109) were higher when using the stiffer cuff at 10% and 20% overlap, respectively. Conclusively, physiological and perceptual responses but not motor performance fatigue were affected by cuff stiffness when equal relative overlaps were applied.

Comparison of clinical outcomes and return to sport between unicortical versus bicortical button fixation techniques for subpectoral biceps tenodesis.

There is limited clinical outcome data comparing fixation methods for tenodesis of the long head of the biceps tendon (LHBT), particularly button fixation. The purpose of this study was to compare clinical outcomes, patient-reported outcomes, and return to sport (RTS) between patients undergoing LHBT with bicortical versus unicortical button technique. The authors hypothesized these fixation methods would be similar for all outcomes. Patients who underwent LHBT using unicortical or bicortical button fixation with minimum 2-year follow-up were identified. Postoperative outcomes were evaluated using the American Shoulder and Elbow Surgeons (ASES) questionnaire and visual analogue scale (VAS) pain score. A sports activity survey was collected to assess baseline sport participation and ability to return to pre-injury activities. Continuous variables were analyzed using the Mann-Whitney-U test. Categorical variables were analyzed using Chi-squared tests. Multivariable logistic and linear regression were performed to determine predictors of RTS and time to RTS. Sixty-four subjects (19 unicortical and 45 bicortical button fixation) were included (average follow-up 3.5 (range: 2.0-7.8) years). There were no significant differences found between button groups for VAS pain score (1.5 vs. 1.2; p = 0.876), VAS pain during sport score (1.6 vs. 1.1, p = 0.398), and ASES score (66 vs. 71; p = 0.294). There were no significant differences in rate of RTS (75.0 vs. 77.4%; p = 0.885) or average time to return to sport (11.7 ± 7.3 vs. 7.0 ± 4.0months; p = 0.081) between groups. There were no significant differences in clinical outcomes, pain, or return to sport between patients who underwent LHBT with unicortical or bicortical button fixation.

Which risk factors are involved in a distal biceps tendon injury? A systematic review.

Distal biceps tendon rupture is a rare injury predominately occurring in middle-aged men. This study aimed to collect relevant risk factors associated with distal biceps tendon rupture from the published literature. This systematic review aimed to collect and tabulate the risk factors for distal biceps tendon rupture. Studies published in English were searched concerning risk factors for distal biceps tendon ruptures until July 2022; cohort studies, case series and randomized controlled trials were subjected to analysis. Case studies, cadaveric studies and reviews in any form were excluded. The studies were quantitatively and qualitatively reviewed. One hundred twenty-one articles presenting risk factors for distal biceps tendon ruptures were identified, recruiting a total of 7,484-7,576 patients. The average age of the individuals was 46.8 years, with 96.7% being males and 94.7% having affinity for sports activities. In 56.7% of the cases, the dominant arm was involved, and in 54.6%, the right arm was affected. The use of tobacco was found in 20.8% of cases and of anabolic steroids in 2.5% of cases. On average, 55.8% of distal biceps tendon rupture patients had a physical occupation and the most common mechanism of the injury was related to heavy weight lifting observed in 53.2% of subjects. The most common and outstanding reported risk factors for distal biceps tendon ruptures were age, sex and sports activity, i.e., middle-aged males being still physically active and practicing sports. Steroid usage does not seem to increase significantly the risk of the distal biceps tendon rupture.

Greater motor unit discharge rate during rapid contractions in chronically strength-trained individuals.

Though similar motor unit (MU) discharge properties have been observed during slow sustained contractions between chronically strength-trained (ST) and untrained (UT) individuals, it is currently unknown if differences between these groups exist for when maximal in vivo MU discharge rate is assessed during rapid, maximal rate of force development (RFD) contractions. Therefore, we compared MU discharge characteristics and RFD during rapid contractions in chronic ST and UT individuals. The investigations were performed in two independent cohorts of chronically ST men, with trained elbow flexors (Experiment 1, n=13, 6±4 years of training experience) or knee extensors (Experiment 2, n=11, 9±4 years of experience), and compared with those of UT (n=12 and n=10, respectively). ST individuals had greater absolute elbow flexion and knee extension RFD throughout the first 150 ms of rapid contractions compared to UT, but this difference was absent for relative RFD. ST exhibited higher initial MU discharge rate in both biceps brachii (74 [68, 80] vs. 56 [50, 63] pps, p<0.0001) and vastus lateralis (102 [90, 115] vs. 76 [63, 90] pps, p=0.0025) and a greater average number of MU discharges per second in both trained muscles in the early phase of rapid contractions. We provide novel evidence for a higher maximal MU discharge rate in strength-trained individuals. Interestingly, despite the augmented output of the spinal cord, no differences in relative RFD were observed, which suggests either greater maximal force enhancement of ST compared to UT and/or slowing of the intrinsic contractile properties by prolonged strength training.

The strength of associations between ultrasound measures of upper limb muscle morphology and isometric muscle strength: An exploratory study.

Assessing upper limb muscle strength is important for understanding health outcomes, such as daily function and mortality. Ultrasound (US) is increasingly used to evaluate muscle health, but the relationship between its measures of morphology and isometric strength has not been thoroughly explored in upper limb muscles. The aim of this study was to evaluate the associations between US morphological measures and isometric strength in functionally relevant upper limb muscles in healthy adults. Twenty-four healthy volunteers (30.0 ± 10.8 years) underwent B-mode, axial US scans of the first dorsal interosseus (FDI), flexor pollicis longus (FPL), biceps brachii (BB), brachialis (BR), and triceps brachii lateral head (TB). Participants performed corresponding maximal voluntary contractions (MVC), including first digit distal phalanx flexion, second digit abduction, and elbow flexion and extension. US images were segmented to obtain maximal muscle thickness (MT) and cross-sectional area (CSA). Strong positive correlations were found between muscle strength and BB MT (r = .83; p < .001), BR CSA (r = .84; p < .001), and TB MT (r = .70; p < .001). Moderate positive correlations were found for strength and FDI CSA (r = .67; p < .001), FDI MT (r = .47; p < .05), FPL CSA (r = .54; p < .01), and FPL MT (r = .42; p < .05). No significant correlation was found between strength and BR MT (r = .16; p > .05). Our data showed moderate-to-strong associations between US muscle morphology and strength, suggesting that US is likely a good biomarker for strength. However, its use is not "one size fits all." Future investigations should continue to assess this relationship in different muscles and expand the generalizability to clinical populations.

Oscillatory drive is increased and steadiness is impaired when torque but not EMG is matched during a fatiguing contraction.

The increasing descending drive needed to sustain a submaximal isometric torque makes it difficult to isolate fatigue-related changes to neural excitability because evoked electromyographic (EMG) responses are influenced by the relative activation of the motoneuron pool. Hence, it is becoming increasingly common to investigate fatigue using a sustained contraction with maintained output from the motoneuron pool; i.e., matched surface EMG. Although this approach controls motoneuron pool output, it is unknown how cortical contributions to ongoing muscle activity or common modulation between muscles is altered during a matched-EMG contraction. During separate visits, 16 participants performed a sustained 10-min isometric elbow flexion contraction at 20% maximal voluntary contraction (MVC) torque or the level of integrated biceps brachii EMG recorded at 20% MVC torque. Electroencephalographic and surface EMG recordings were obtained from the sensorimotor area and biceps and triceps brachii, respectively. The matched-torque contraction caused increased corticomuscular coherence for biceps brachii (~75%) and intermuscular coherence (~97%), but reduced MVC torque (~33%), voluntary activation (~9%), and torque steadiness (~83%). In contrast, the matched-EMG contraction caused reduced MVC torque (~21%), with no change in coherence, voluntary activation, or EMG steadiness. Further, participants reported higher ratings of perceived effort scores by 6min into the matched-torque compared to matched-EMG contraction. These findings indicate that, during a matched-torque contraction, the nervous system enhances common oscillatory activity to continue the task, but this does not prevent degradation of performance (torque steadiness). In contrast, when motoneuron pool output was clamped, other neural strategies are used to maintain muscle output.

Development of a seat support mechanism for guiding users to an appropriate posture in a seated-style echocardiography robot

Abstract This paper proposes a seat support mechanism to solve the problem of misalignment between the chest examination and probe scanning areas when the patient is bent in a seated-style echocardiography robot. To guide the patient to an appropriate body position where their chest is within the examination range of the chest examination unit while minimizing the physical load of the patient, the posture of the patient must satisfy the three following conditions. (i) The breech must be in contact with the seat surface, (ii) the legs must be vertical to the floor, and (iii) the chest and mechanism must be parallel while the probe scanning and chest examination ranges must match. The human body was modeled to derive a posture that satisfies the aforementioned conditions for the height of each individual, and a seat support mechanism with four degrees of freedom was installed to guide the user to the derived posture. By installing this mechanism, the body load of the left biceps brachii, right biceps brachii, left latissimus dorsi, and right latissimus dorsi was reduced to 64.7%, 52.7%, 86.4%, and 80.2%, respectively. The sharpness of the image contours was improved to 103.8%.

Corticospinal and corticoreticulospinal projections have discrete but complementary roles in chronic motor behaviors after stroke.

After corticospinal tract (CST) stroke, several motor deficits can emerge in the upper extremity (UE), including diminished muscle strength, motor control, and muscle individuation. Both the ipsilesional CST and contralesional corticoreticulospinal tract (CReST) innervate the paretic UE, but their relationship to motor behaviors after stroke remains uncertain. In this cross-sectional study of 15 chronic stroke and 28 healthy subjects, we examined two questions: whether the ipsilesional CST and contralesional CReST differentially relate to chronic motor behaviors in the paretic arm and hand, and whether the severity of motor deficits differ by proximal versus distal location. In the paretic biceps and first dorsal interosseous muscles, we therefore used transcranial magnetic stimulation to measure the projection strengths of the ipsilesional CST and contralesional CReST. We also used quantitative testing to measure strength, motor control, and muscle individuation in each muscle. Stroke subjects had comparable muscle strength to healthy subjects but poorer motor control and muscle individuation. In both muscles, stronger ipsilesional CST projections related to better motor control, whereas stronger contralesional CReST projections related to better muscle strength. Stronger CST projections related to better individuation in the biceps alone. The severity of motor control and individuation deficits was comparable in the arm and hand. These findings suggest that the ipsilesional CST and contralesional CReST have specialized but complementary roles in motor behaviors of the paretic arm and hand. They also suggest that deficits in motor control or muscle individuation are not segmentally biased, underscoring the functional reach and efficacy of the pathways.

Surface electromyography character of upper limb muscle after open reduction combine with ulnar osteotomy in children with neglected Monteggia fracture

ObjectiveThis study aims to investigate the surface electromyography (sEMG) characteristics of upper limb muscles in children with neglected Monteggia fracture after open reduction of radial head dislocation and ulna osteotomy and bone grafting internal fixation, and to understand the recovery of muscle activity in children after operation, provide reference for clinical rehabilitation.MethodsA retrospective analysis was conducted on sixteen children with neglected Monteggia fracture who underwent ulna osteotomy at our hospital from January 2021 to August 2022. The biceps brachii, triceps brachii, flexor carpi radialis, and extensor carpi ulnaris muscle activities were recorded during grip strength tests, flexion and extension of elbow joint while holding a 1 kg dumbbell, as well as gripping tasks. The root mean square (RMS) values of sEMG signals, co-contraction ratio, and elbow joint function scores were compared between pre- and post-operation periods as well as between the affected side and unaffected side.ResultsThe preoperative maximum grip strength, as well as the average RMS values of flexor carpi radialis and average RMS value of extensor carpi ulnaris on the affected side were significantly lower. After surgery, both the maximum RMS value of biceps brachii and maximum and average RMS value of extensor carpi ulnaris on the affected side remained lower. Prior to surgery, when performing elbow flexion and extension tests while holding a 1 kg dumbbell, both mean RMS values of biceps brachii and flexor carpi radialis on the affected side were smaller. However, after surgery, there was an increase in mean RMS values of biceps brachii on the affected side. Furthermore, postoperative elbow function scores were significantly higher than preoperative scores.ConclusionOpen reduction of radial head dislocation combined with ulna osteotomy and bone grafting can achieve good functional activities in the treatment of neglected Monteggia fractures in children. The EMG activity of the extensor carnosus ulnalis muscle on the affected side related to grip strength was low, and the desired effect was not achieved within the expected time.

The use of lifting straps during snatch alters muscle activation patterns

The snatch is prevalent in competitive and recreational lifting as well as strength training. Lifting straps (LS) are an accessory that wrap around the hand and the barbell, reducing the limitations of grip strength. However, this benefit has not been quantitatively supported for the snatch. The aim of this study was to compare muscle activation patterns between using LS and not using them at 80% of the snatch one-repetition maximum in a group of twelve sub-elite male weightlifters. It was hypothesized that LS would decrease forearm muscle activation and increase larger muscle group activation. Eight dominant-side muscles located in the lower limbs, back, shoulders, and upper limbs were measured via electromyography. A two-way analysis of variance (ANOVA), followed by a Tukey Pairwise comparison, revealed that LS significantly impacted (p = 0.039) muscle activation in the snatch. Specifically, latissimus dorsi activation increased the most (17.2 ± 55.7%), while biceps brachii activation decreased the most (−8.0 ± 37.0%). Comparing muscle activation across different phases of the lift showed that LS decreased forearm and bicep brachii activation by 16.0 ± 25.2% and 7.1 ± 35.7% respectively during the pull phase, and increased vastus lateralis, latissimus dorsi, and medial deltoid activation between the second part of the first pull and the catching position, with a corrected effect size exceeding 1.5. These results support the hypothesis that LS decrease forearm activation, which could reduce grip strength limitations and consequently, reduce problems associated with fatigue. Increases in vastus lateralis activation with the use of LS suggest a greater training stimulus during the snatch, which can help develop leg strength.

Effects of Kitchen Cooking Height on Upper Limb Muscle Activation, Posture, and Perceived Discomfort of Chinese Older and Young Women.

Inappropriate kitchen cooking height may lead to uncomfortable and muscle fatigue. This study aims to compare the effects of kitchen cooking height on upper limb muscle activation, posture, and perceived discomfort among different age groups. Fifteen older women and fifteen young Chinese women each completed three consecutive 20 s simulated cooking tasks at five different heights. Surface electromyography, motion capture, and Borg CR10 scale were used to measure muscle loading. Results showed that the main power muscles of the cooking task were the anterior deltoid, brachioradialis, and biceps brachii. The higher muscle contribution rate of biceps brachii and triceps brachii was found in the younger group compared to the older group (p < 0.05). Muscle activation of the anterior deltoid (different in 1.28-2.87%), pectoralis major (different in 1.43-1.69%), and erector spinae (different in 0.6-1.21%), as well as right shoulder abduction (different in 5.91°-7.96°), were significantly higher in older group than in young group (p < 0.05). Muscle activation of the anterior deltoid and right shoulder abduction decreased significantly with decreasing height (p < 0.05). A height of 200-250 mm below the elbow was considered a more comfortable cooking height for both age groups. This provides data to support the design of cabinet sizes.

Comparison of muscle activation during quadrupedal movement training and traditional bodyweight exercises

Quadrupedal movement training (QMT) is a unique form of bodyweight training shown to improve flexibility, FMS scores, and proprioception, however, little is known about its muscle activation characteristics. Therefore, the purpose of this study was to compare surface EMG (sEMG) activity of muscles of the trunk, upper, and lower extremity during QMT movements and common traditional bodyweight exercises (TRA). Twenty (males n = 9) participants (age: 27.5 ± 10.8 yrs, height: 169.0 ± 7.0 cm, mass: 66.6 ± 10.9 kg) were prepped and fitted with sEMG electrodes on their right-side bicep brachii, medial deltoid, triceps brachii, pectoralis major, latissimus dorsi, rectus abdominus, rectus femoris and bicep femoris. Following completion of maximal voluntary isometric contraction (MVIC) tests for normalization, participants performed 4 repetitions of 8 QMT exercises (from the Animal Flow™ system) and 3 TRA exercises (pushup, squat and forearm plank) in random order. The pooled peak muscle activations of all QMT exercises resulted in moderate (21–40% MVIC) to very high (>60% MVIC) peak muscle activation levels for each muscle group with significantly higher (p > 0.05) muscle activation for the biceps (47.72 ± 21.41%), deltoid (66.58 ± 11.39%), and latissimus dorsi (62.81 ± 18.14%) than the pushup (23.31 ± 16.95, 45.63 ± 18.59, 29.17 ± 20.58% respectively) and significantly higher activation of the bicep femoris (41.89 ± 13.83%) than the squat (17.79 ± 11.12%). TRA (pushup) showed significantly higher activation of the triceps and pectoralis. There were no differences in rectus femoris or rectus abdominus. Muscle activation levels during QMT are comparable to or higher than common traditional bodyweight exercises and therefore may be an appealing strategy for training multiple muscle groups simultaneously.

Effect of Skeletal Muscle Immobilization on Regional Anisotropic Viscohyperelastic Properties Change in a Rat Model

Passive mechanical properties in three different zones (distal, proximal, and medial) of biceps brachii immobilized in short position and its free contralateral were investigated. For that, in vitro equibiaxial relaxation tests were performed with samples harvested from skeletal muscles of immobilized rats during one or two weeks. From data obtained in two plane axes of loading, a viscohyperelastic anisotropic model described by a strain energy function coupled with second order Maxwell's model, was used to identify the material parameters. It has been shown that the zone influences the material parameters of the hyperelasticity behavior while the immobilization acts rather on the viscoelasticity response. Based on measurements of histological parameters from flexor carpi ulnaris muscles, we observed that immobilization produced contractile tissue atrophy and connective tissue thickening. The muscle atrophy caused by immobilization could lead to a more linear mechanical behavior along the axis of the muscle fibers. Furthermore, fibrosis, quantified by histological analysis on flexor carpi ulnaris muscles, could result in highly non-linear behavior along the other axis. These structural changes also contribute to an increase in relaxation following immobilization along both axes (+11.7% and +15.5% on average with p < 0.001 and p < 0.01 respectively for each axis). Statement of significanceTo our best knowledge, this work is the first to investigate the anisotropic, viscohyperelastic and heterogeneous properties within a passive skeletal muscle immobilized in a short position. For that, from a rat model, equibiaxial relaxation tests were performed and material parameters were found from a strain energy function coupled with a Maxwell's model. We showed that excising zone of samples greatly influences the parameters of the hyperelastic behavior while the immobilization influences the viscoelasticity response instead. Furthermore, histological analysis permitted to quantify fibrosis in the skeletal muscle and bear out, at least in part, changes in relaxation behavior following immobilization.

Characteristics of Human Postactivation Effect of Skeletal Muscles Using Spectral and Non-Linear Parameters of the Surface Electromyogram

Postactivation effect (PAE, postactivation phenomenon) is a specific type of involuntary muscle tone (tonic automatism) which is generated in the “tonogenic” structures of the brain, presumably without the “sensory copy” and “motor command” mechanisms. In this regard, the electromyogram (EMG) signal of PAE may have a simpler temporal signal structure compared to PAE-inducing voluntary activity. The purpose of this work is to characterize the temporal structure and complexity of surface EMG (sEMG) of the human deltoid and biceps brachii muscles using fractal (D) and correlation dimensions (Dc). It was found that in deltoid muscles the value of D was 1.78–1.81 both during PAE and voluntary effort (p 0.05). Dc (approximately 4.0–4.2) also did not differ between PAE and voluntary effort, although the average frequency of the sEMG spectrum during PAE was 15–16 Hz (p 0.05) higher compared to voluntary effort. In biceps brachii muscles, the D value was 1.8 during PAE and 1.62 during voluntary effort (p 0.05). Dc values did not differ between PAE and voluntary contraction (4–4.8). Thus, despite the supposed difference in the central organization of PAE and voluntary effort, the temporal structure of their sEMG did not differ, indicating that isometric voluntary effort and involuntary tone in the form of PAE share a common principle of sEMG signal generation. At the same time, the differences in the frequency of the sEMG spectrum indicate that the organization of sEMG signal during PAE is specific on the level of the motoneuron pool.

Comparison Between InterCriteria and Correlation Analyses over sEMG Data from Arm Movements in the Horizontal Plane

InterCriteria analysis (ICrA) and two kinds of correlation analyses, Pearson (PCA) and Spearman (SCA), were applied to surface electromyography (sEMG) signals obtained from human arm movements in the horizontal plane. Ten healthy participants performed ten movements, eight of which were cyclic. Each cyclic movement (CM) consisted of flexion and extension phases with equal duration (10 s, 6 s, 2 s, and 1 s) and two 5 s rest poses between them. The CMs were performed with and without an added load of 0.5 kg on the wrists of the participants. The sEMG signals from six different muscles or separate muscle heads (m. deltoideus pars clavicularis, m. deltoideus pars spinata, m. brachialis, m. anconeus, m. biceps brachii, and m. triceps brachii long head) were recorded and used to compare the results of the ICrA, PCA, and SCA. All three methods found identical consonance pairs for the flexion and extension CM phases. Additionally, PCA detected two more consonance pairs in the extension phases. In this investigation, ICrA, PCA, and SCA were proven to be reliable tools when applied separately or in combination for sEMG data. These three methods are appropriate for researching arm movements in the horizontal plane and experimental protocol revision.

Comparing A-mode ultrasound and computed tomography for assessing cancer-related sarcopenia: A cross-sectional study.

A-mode ultrasound (US) is a potential method for directly measuring muscle thickness in patients with cancer, but its utility remains underexplored. We aimed to evaluate the feasibility of using A-mode US to assess muscle thickness, compare it with computed tomography (CT)-derived results, and assess its ability to diagnose sarcopenia. A cross-sectional analysis was conducted with hospitalized patients with cancer. Muscle cross-sectional area (CSA) was derived from CT scans. Biceps muscle thickness (BMT) and thigh muscle thickness (TMT) by A-mode US were assessed. BMT + TMT were also combined as an additional phenotype. Muscle strength was assessed using handgrip strength (HGS) test. Sarcopenia was defined as low muscle mass (CT- and US-derived) + low HGS. We included 120 patients (53.3% women, 45% older adults, and 85.8% with disease stages III-IV). TMT alone and the combined approach (BMT + TMT) were weak and positively correlated and significantly associated with muscle CSA, explaining 35% of CSA variability (R2 = 0.35). TMT individual and combined with BMT exhibited the highest accuracy for men (area under the curve >0.70). Sarcopenia diagnosed by BMT + TMT exhibited the highest frequency (34%) and moderate agreement with CT-derived sarcopenia (κ = 0.48). A-mode US has the potential to be a feasible tool for diagnosing sarcopenia in clinical practice at the bedside for patients with cancer despite the need for further improvements in the tool's accuracy. Our main findings suggest that combining measurements of BMT and TMT may enhance its clinical significance in diagnosing sarcopenia.

Supernumerary Head of the Biceps Brachii Muscle Influences the Topography of the Coracobrachialis and Biceps Brachii Muscles

Background/Objectives: Anatomical variations in the biceps brachii muscle (BBM) are extremely frequent, leading to developmental and clinical implications. We studied the topography of the BBM and analyzed its correlations with other structures in the brachial region. Methods: A total of 103 cadaveric upper extremities were dissected. The length of the upper extremities was utilized as a reference line. The origin and insertion of the BBM, the coracobrachialis muscle (CBM), and the related neurovascular system were evaluated. Results: Each variable was calculated as a percentile and compared according to the presence of the considered variation; in particular, a supernumerary head of the BBM was found in 12/103 (11.65%) of upper extremities and was associated with a longer upper limb (506.25 ± 32.55 mm vs. 484.27 ± 30.41 mm, p = 0.022). When the variables were standardized by the length of the upper limb, the accessory head of the BBM was associated with the distal insertion point of the CBM (28.18 ± 3.54% vs. 30.59 ± 2.94%, p = 0.011) and BBM length (55.11 ± 2.17% vs. 58.18 ± 3.72%, p = 0.006). Other variables did not present significant differences with respect to the presence of the supernumerary head of the BBM. Conclusions: BBM variations may affect the topography of other structures, such as the length of the upper extremities, insertion of the CBM, and length of the BBM. Further studies are required to elucidate its clinical implications.

Effect of fatigue on intermuscular EMG-EMG coupling during bench press exercise at 60% 1RM workload in males.

To explore the neuromuscular control mechanism and quantifying the fatigue response during bench press exercise is important references to prescribe an appropriate exercise program. However, current literature struggles to provide a concrete conclusion on the changes of intermuscular EMG-EMG coupling between synergistic and antagonist muscles during the exercise. Thus, the current study was designed to reveal fatigue-related changes of intermuscular EMG-EMG coupling during bench press exercise. Thirty-one healthy male participants performed a bench press exercise on the Smith machine at 60% One Repetition Maximum (1RM) workload to exhaustion, while surface electromyographic signals (sEMG) were collected from triceps brachii (TB), biceps brachii (BB), anterior deltoid (AD), posterior deltoid (PD), and pectoralis major (PM). Surface EMG signals were divided into the first half and second half of the bench press exercise. Phase synchronization index (PSI) was calculated between sEMG of synergistic muscle pairs AD-TB, AD-PM and antagonist muscle pairs BB-TB, AD-PD. EMG power of TB, AD, PD, PM muscles in alpha (8-12 Hz) frequency band and EMG power of each muscle in beta (15-35 Hz), and gamma (35-60 Hz) frequency bands were all increased during the second half of contraction compared with the first half of contraction. PSI of gamma frequency band was significantly decreased in BB-TB muscle pair while EMG-EMG coupling of AD-TB in gamma frequency band was significantly increased during the second half of contraction compared to the first half of contraction. The results indicated a decrease of interconnection between synchronized cortical neurons and the motoneuron pool of BB and TB, and an increase of interconnection between AD-TB muscles during fatiguing bench press exercise at 60% 1RM workload. The changes of intermuscular coupling may be related to the supraspinal modulations to compensate for the decrease of muscle force as well as a result of unbalanced changes of agonist and antagonist muscle contractility.

The association between ultrasonographic findings and pain, physical function, and symptoms in patients with shoulder pain.

Shoulder ultrasonography (US) is commonly employed to differentiate the causes of shoulder pain. However, the correlation between ultrasonographic findings and the individual's functional disability and daily activities remains unexplored. To investigate the relationship between shoulder US findings and physical function, disability, and pain. The study investigated patients with shoulder pain. Tendons of supraspinatus, infraspinatus, subscapularis, and long head of biceps brachii, acromiohumeral distance, and acromioclavicular joint (ACJ) degeneration were evaluated using US. The QuickDASH questionnaire was employed to evaluate physical function, symptoms, and disability, while the visual analog scale (VAS) was utilized to assess pain levels. The study included 84 patients (69 [82.1%] women, mean age = 55.7 ± 11.9 years). Ultrasonographic examination revealed ACJ degeneration in 61 (21.4%) patients and biceps tendinitis in 21 (25%) patients. In addition, supraspinatus tendinosis was identified in 51 (61%) patients, while 28 (33%) exhibited a supraspinatus tear. The patients demonstrated a mean VAS score of 7.03 ± 1.49 and mean QuickDASH score of 45.6 ± 15.3. Individuals with a supraspinatus tear exhibited higher VAS (P = 0.008) and QuickDASH (P = 0.016) scores. Patients presenting with ACJ degeneration demonstrated increased VAS scores (P = 0.014), whereas those with biceps tendinopathy showed higher QuickDASH scores (P = 0.035). The results obtained from our research demonstrate significant correlations between ultrasonographic data and pain, disability, and physical manifestations. The findings of this study indicate that shoulder US provides valuable information regarding the difficulties individuals face in their daily tasks and the degree of pain they endure.

THE EFFECT OF EXERCISES OF DIFFERENT INTENSITY APPLIED AFTER TOTAL KNEE ARTHROPLASTY ON POST-OPERATIVE PAIN: RANDOMIZED CONTROLLED TRIAL

Purpose: This study aimed to investigate the changes in pain following exercise sessions with different intensities in patients who underwent total knee arthroplasty (TKA). Methods: This is a repeated measure and single-blinded randomized controlled study. Thirty-six patients who underwent TKA (age, 64.9 ± 7.42 years) were randomly assigned to either low-intensity exercises (LIEs) group or high-intensity exercises (HIEs) group. Exercise programs lasted for five days during the hospitalization period. Pain intensity was assessed by visual analog scale (VAS) and pressure pain thresholds (PPTs) were measured over quadriceps and biceps brachii and muscles immediately before and after exercise. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscale (pain, stiffness, and physical function) scores were recorded at two points in baseline and discharge from the hospital. Results: The pain intensity decreased in patients in both groups after TKA. PPTs increased in both groups at all tested sites following the first, third, and fifth exercise bouts. HIE program had a greater positive effect on the pain intensity after the first exercise session than LIE program on the PPTs ([Formula: see text] &lt; 0.05). HIE program was more effective in order to reduce pain severity immediately after the exercise sessions in patients ([Formula: see text]: 0.5, [Formula: see text] &lt; 0.05). WOMAC scores significantly improved in both groups during the discharge from the hospital ([Formula: see text] = 0.001). Conclusion: Our results found that both LIE and HIE programs performed during hospitalization after TKA declined pain intensity. Particularly notable were the substantial improvements observed in managing post-operative pain, especially following the second exercise session. The HIE program proved more effective in improving stiffness, and enhancing physical function.