Biceps Research Articles

Contribution of external reference frame to tactile localization.

The purpose of the present study was to elucidate whether an external reference frame contributes to tactile localization in blindfolded healthy humans. In a session, the right forearm was passively moved until the elbow finally reached to the target angle, and participants reached the left index finger to the right middle fingertip. The locus of the right middle fingertip indicated by the participants deviated in the direction of the elbow extension when vibration was provided to the biceps brachii muscle during the passive movement. This finding indicates that proprioception contributes to the identification of the spatial coordinate of the specific body part in an external reference frame. In another session, the tactile stimulus was provided to the dorsal of the right hand during the passive movement, and the participants reached the left index finger to the spatial locus at which the tactile stimulus was provided. Vibration to the biceps brachii muscle did not change the perceived locus of the tactile stimulus indicated by the left index finger. This finding indicates that an external reference frame does not contribute to tactile localization during the passive movement. Humans may estimate the spatial coordinate of the tactile stimulus based on the time between the movement onset and the time at which the tactile stimulus is provided.

Brachial Plexus Injury Influences Efferent Transmission on More than Just the Symptomatic Side, as Verified with Clinical Neurophysiology Methods Using Magnetic and Electrical Stimulation.

The variety of sources of brachial plexus injuries (BPIs) and the severity and similarity of their clinical symptoms with those of other injuries make their differential diagnosis difficult. Enriching their diagnosis with objective high-sensitivity diagnostics such as clinical neurophysiology may lead to satisfactory treatment results, and magnetic stimulation (MEP) might be an advantageous addition to the diagnostic standard of electrical stimulation used in electroneurography (ENG). The asymptomatic side in BPI cases sometimes shows only subclinical neurological deficits; this study aimed to clarify the validity and utility of using MEP vs. ENG to detect neural conduction abnormalities. Twenty patients with a BPI and twenty healthy volunteers with matching demographic and anthropometric characteristics were stimulated at their Erb's point in order to record the potentials evoked using magnetic and electrical stimuli to evaluate their peripheral motor neural transmission in their axillar, musculocutaneous, radial, and ulnar nerves. MEP was also used to verify the neural transmission in participants' cervical roots following transvertebral stimulations, checking the compatibility and repeatability of the evoked potential recordings. The clinical assessment resulted in an average muscle strength of 3-1 (with a mean of 2.2), analgesia that mainly manifested in the C5-C7 spinal dermatomes, and a pain evaluation of 6-4 (mean of 5.4) on the symptomatic side using the Visual Analog Scale, with no pathological symptoms on the contralateral side. A comparison of the recorded potentials evoked with magnetic versus electrical stimuli revealed that the MEP amplitudes were usually higher, at p = 0.04-0.03, in most of the healthy volunteers' recorded muscles than in those of the group of BPI patients, whose recordings showed that their CMAP and MEP amplitude values were lower on their more symptomatic than asymptomatic sides, at p = 0.04-0.009. In recordings following musculocutaneous and radial nerve electrical stimulation and ulnar nerve magnetic stimulation at Erb's point, the values of the latencies were also longer on the patient's asymptomatic side compared to those in the control group. The above outcomes prove the mixed axonal and demyelination natures of brachial plexus injuries. They indicate that different types of traumatic BPIs also involve the clinically asymptomatic side. Cases with predominantly median nerve lesions were detected in sensory nerve conduction studies (SNCSs). In 16 patients, electromyography revealed neurogenic damage to the deltoid and biceps muscles, with an active denervation process at work. The predominance of C5 and C6 brachial plexus injuries in the cervical root and upper/middle trunk of patients with BPI has been confirmed. A probable explanation for the bilateral symptoms of dysfunction detected via clinical neurophysiology methods in the examined BPI patients, who showed primarily unilateral damage, maybe the reaction of their internal neural spinal center's organization. Even when subclinical, this may explain the poor BPI treatment outcomes that sometimes occur following long-term physical therapy or surgical treatment.

How to Optimize the Experimental Protocol for Surface EMG Signal Measurements Using the InterCriteria Decision-Making Approach

The InterCriteria decision-making approach, known as InterCriteria analysis (ICrA), was applied here to optimize the experimental protocol when the surface electromyography (EMG) signals of upper arm human muscles are recorded. Ten healthy subjects performed cycling movements in the sagittal plane with and without added weight for ten, six, two, and one second, respectively, for each active phase. The EMG signals from six muscles, namely m. deltoideus pars clavicularis and pars spinata, m. brachialis, m. anconeus, m. biceps brachii, and m. triceps brachii caput longum, were recorded. ICrA was used on the obtained data to find correlations between the sixteen different phases, eight for elbow flexion and eight for elbow extension. Based on the obtained results, we proposed an optimized experimental protocol (OEP) that omits slower and more difficult tasks while saving crucial data. The optimized protocol consists of seven, instead of ten, tasks and takes three minutes less than the time taken for the full experimental protocol (FEP). The lower number of movements in the OEP could prevent physical and psychical fatigue, discomfort, or even pain in the investigated subjects. In addition, the time to train subjects, as well as the time to process the surface EMG data, can be significantly reduced.

Does the Extent of Tear Influence Pseudoparesis in Patients With Isolated Subscapularis Tears?

Surgeons tend to associate pseudoparesis with massive rotator cuff tears. However, little is known about the degree to which isolated subscapularis tears might be associated with pseudoparesis of the shoulder. Is the extent of subscapularis tears associated with pseudoparesis? A retrospective analysis identified all patients with subscapularis tears from 2010 to 2021 in the longitudinally maintained shoulder arthroscopy archive of one university hospital's shoulder section of the orthopaedic department. After exclusion, 106 of 152 patients with isolated subscapularis tears who underwent arthroscopic surgery were included in the study. Sixty percent of the patients were women, and the mean ± SD age was 52 ± 11 years. Patients who were scheduled for arthroscopic surgery were divided into two groups according to the presence or absence of pseudoparesis preoperatively. Pseudoparesis was considered to be active forward elevation > 45º but < 90º, which is a simple and reproducible measurement that can be taken using a goniometer, and demonstrated complete passive forward elevation. Pseudoparesis was present in 41% (43 of 106) of patients with an isolated subscapularis tear. Data on tear severity (according to Lafosse type, noted during arthroscopy), integrity of the subscapularis tendon (noted during arthroscopy), fatty degeneration (using the Goutallier grading system on MRI), arthroscopic findings of biceps disorder, superior labrum anterior to posterior (SLAP) lesions, and pain severity (measured by VAS score) were recorded. We used logistic regression analysis to examine the relationship between pseudoparesis and disruption of the tendinous part of the subscapularis. After accounting for potentially confounding factors such as biceps disorders and muscle atrophy, we found that pseudoparesis was associated with decreased tear severity according to the Lafosse classification (adjusted OR 0.2 [95% CI 0.1 to 0.7]; p = 0.01) and with disruption of the tendinous portion of the subscapularis (adjusted OR 21 [4 to 128]; p = 0.001). Patients with less severe tears (Lafosse type I) have lower odds of experiencing pseudoparesis compared with those with more severe tears (Lafosse types II, III, and IV), and patients with disruption of the tendinous portion of the subscapularis have substantially higher odds of pseudoparesis compared with those with an intact tendinous portion. No association was found between pseudoparesis and subscapularis fatty degeneration, biceps disorder, or SLAP lesions. This study provides initial evidence suggesting that isolated subscapularis tears are associated with pseudoparesis. The main finding of this study is that isolated subscapularis tears that involve the tendon extending to the inferior part of the subscapularis have higher odds of being found with pseudoparesis. These findings highlight the importance of maintaining the integrity of the superior tendinous part of the subscapularis for active forward elevation > 90°. Level III, therapeutic study.

All-Suture Anchor Techniques for Biceps Tenodesis Are Noninferior in End-Cycle Stiffness to an Interference Screw Technique; However, Secondary Outcomes, Such as Ultimate Failure Load, Yield Load, Creep, and Load-to-Failure Stiffness, Are Inferior in an Ovine Model

PurposeThe purpose of this study was to assess the biomechanical performance of two simplified loop and tack biceps tenodesis techniques, all-suture anchor and all-suture anchor with a button, compared to the interference screw technique in an ovine model. MethodsTwenty-one biceps tenodesis procedures were executed on the humeri and flexor digitorum profundus tendons of skeletally mature, female sheep. Limbs were evenly randomized into two experimental groups (all-suture anchor with/without button) and one control group (interference screw). Cyclic loading followed by a load-to-failure test was conducted.The primary outcome metric was end-cycle stiffness, or stiffness measured at the end of cyclic loading, as it modeled the resistance of the construct to the lower-force activities of postoperative physical therapy. Secondary metrics included ultimate failure load (UFL), yield load, creep, and load-to-failure stiffness. End-cycle stiffness difference-of-means testing was conducted with a minimal clinically significant difference (MCID) threshold of -15N/mm (1.5kg/mm). Groups were compared using ANOVA for all recorded variables. ResultsBoth the all-suture anchor and all-suture anchor with button techniques were found to be noninferior in end-cycle stiffness compared to the interference screw technique (-5.2N/mm, 95% CI [-13.6, 3.3] and –3.8N/mm, 95% CI [-12.5, -4.9]) for -15N/mm MCID. The all-suture techniques showed significantly lower UFL, lower yield load, greater creep, and lower load-to-failure stiffness (P<0.001, P<0.001, P=0.002, P<0.001, respectively). Tendon dimensions did not vary significantly across groups. ConclusionsUnder subfailure loading conditions, the all-suture anchor with/without button techniques demonstrated end-cycle stiffness noninferiority with an interference screw technique, however, these techniques were inferior in all secondary outcomes, including significantly lower UFL, lower yield load, greater creep, and lower load-to-failure stiffness. Clinical RelevanceThe all-suture anchor with/without button approaches may retain the natural length-tension dynamics of the long head biceps tendon as fixation can occur before releasing the tendon origin. Additionally, it may offer a simpler and more cost-effective alternative to prevailing arthroscopic methods.

Use of acoustic myography in evaluation of biceps brachii and triceps brachii muscle function in nine skijoring dogs

Abstract Studies have found pain and inflammation in the shoulder region of working sled dogs. As skijoring is a comparable, competitive winter sport, this act may result in injuries similar to those seen in sled dogs. The purpose of this study was to assess the duration of muscle contraction, temporal, and spatial summation (E-, S-, and T-scores) of the biceps and triceps brachii muscles and compare between skijoring and free-running. Nine skijoring dogs completed a free-run and skijoring trial on the same trail in random order. Acoustic myography (AMG), measuring on:off ratio (E-score), spatial summation (S-score), and temporal summation (T-score) of the biceps and triceps brachii was performed comparing the muscle work during skijoring and free-running tasks ensuring minimal acceleration during each recording period. Statistical analyses included Shapiro-Wilk tests, paired Student’s t-tests, two-way ANOVAs, and Mann-Whitney U tests. Significance was set at . When comparing the E-, S- and T-scores of the experienced dogs, the E-score of the triceps brachii was significantly lower during skijoring compared to free-running. When comparing the biceps versus the triceps in all dogs, T-score for the biceps was significantly lower than that of the triceps during skijoring. Males were significantly faster than the females during both the free-running and skijoring tasks. Males all fell in the experienced dog group. In experienced dogs, the increase in triceps workload during the task of skijoring with no apparent change in its antagonist, the biceps, could result in excess tension on the musculotendinous unit of the biceps. The relative workload of the biceps versus the triceps appears higher regarding temporal summation during skijoring.

Long-Term Resistance Trained Human Muscles Have More Fibers, More Myofibrils, and Tighter Myofilament Packing Than Untrained.

Increases in skeletal muscle size occur in response to prolonged exposure to resistance training that is typically ascribed to increased muscle fiber size. Whether muscle fiber number also changes remains controversial, and a paucity of data exists about myofibrillar structure. This cross-sectional study compared muscle fiber and myofibril characteristics in long-term resistance-trained (LRT) versus untrained (UNT) individuals. The maximal anatomical cross-sectional area (ACSAmax) of the biceps brachii muscle was measured by magnetic resonance imaging in 16 LRT (5.9 ± 3.5 yr' experience) and 13 UNT males. A muscle biopsy was taken from the biceps brachii to measure muscle fiber area, myofibril area, and myosin spacing. Muscle fiber number, and myofibril number in total and per fiber were estimated by dividing ACSAmax by muscle fiber area or myofibril area, and muscle fiber area by myofibril area, respectively. Compared with UNT, LRT individuals had greater ACSAmax (+70%, P < 0.001), fiber area (+29%, P = 0.028), fiber number (+34%, P = 0.013), and myofibril number per fiber (+49%, P = 0.034) and in total (+105%, P < 0.001). LRT individuals also had smaller myosin spacing (-7%, P = 0.004; i.e., greater packing density) and a tendency toward smaller myofibril area (-16%, P = 0.074). ACSAmax was positively correlated with fiber area ( r = 0.526), fiber number ( r = 0.445), and myofibril number (in total r = 0.873 and per fiber r = 0.566), and negatively correlated with myofibril area ( r = -0.456) and myosin spacing ( r = -0.382) (all P < 0.05). The larger muscles of LRT individuals exhibited more fibers in cross-section and larger muscle fibers, which contained substantially more total myofibrils and more packed myofilaments than UNT participants, suggesting plasticity of muscle ultrastructure.

Comparison of Myoelectric Activity Between Standing and Lying Plate Press Exercises in Recreationally-Trained Participants

The plate press is a multi-joint exercise that involves the elbow and shoulder joints and can be performed in two different body positions (lying and standing). The purpose of this study was to evaluate the myoelectric activity between two different plate press exercises (lying and standing) in recreationally-trained men. Fifteen resistance-trained men (26.7 ± 3.2 years, 83.1 ± 6.8 kg, 176.0 ± 6.4 cm) performed one set of 10 repetitions with a standard weight of 10kg for the standing and lying plate press exercises at 60 beats per minute. Surface electromyography was used to measure the myoelectric activity (integrated electromyography, iEMG) of the pectoralis major (PM), anterior deltoid (AD), triceps brachii (TB), and biceps brachii (BB). Two-way ANOVA (2 x 4) with repeated-measures was used to test differences between exercises and muscle groups (PM, AD, TB, and BB) for the iEMG values. There were significant differences between exercises for AD (Standing &gt; Lying: 41.7\%, p=0.05), TB (Lying &gt; Standing: 51.4\%, p=0.047), and BB (Standing &gt; Lying: 54.6\%, p=0.001). In the comparison between muscle groups, TB presented the lowest myoelectric activation for the standing plate press exercise (57.6\%, p&lt;0.05) and BB presented the lowest myoelectric activation for the lying plate press exercise (48.1\%, p&lt;0.05). In conclusion, the lying plate press exercise showed a greater myoelectric activation of the TB and the standing plate press exercise showed greater myoelectric activation of the AD and BB. PM showed high myoelectric activation in both exercises but with no difference between exercises.

Automatic Quantitative Assessment of Muscle Strength Based on Deep Learning and Ultrasound.

Skeletal muscle is a vital organ that promotes human movement and maintains posture. Accurate assessment of muscle strength is helpful to provide valuable insights for athletes' rehabilitation and strength training. However, traditional techniques rely heavily on the operator's expertise, which may affect the accuracy of the results. In this study, we propose an automated method to evaluate muscle strength using ultrasound and deep learning techniques. B-mode ultrasound data of biceps brachii of multiple athletes at different strength levels were collected and then used to train our deep learning model. To evaluate the effectiveness of this method, this study tested the contraction of the biceps brachii under different force levels. The classification accuracy of this method for grade 4 and grade 6 muscle strength reached 98% and 96%, respectively, and the overall average accuracy was 93% and 87%, respectively. The experimental results confirm that the innovative methods in this paper can accurately and effectively evaluate and classify muscle strength.

Mapping of spastic muscle activity after stroke: difference between passive stretch and active contraction

BackgroundInvestigating the spatial distribution of muscle activity would facilitate understanding the underlying mechanism of spasticity. The purpose of this study is to investigate the characteristics of spastic muscles during passive stretch and active contraction by high-density surface electromyography (HD-sEMG).MethodsFourteen spastic hemiparetic subjects and ten healthy subjects were recruited. The biceps brachii (BB) muscle activity of each subject was recorded by HD-sEMG during passive stretch at four stretch velocities (10, 60, 120, 180˚/s) and active contraction at three submaximal contraction levels (20, 50, 80%MVC). The intensity and spatial distribution of the BB activity were compared by the means of two-way analysis of variance, independent sample t-test, and paired sample t-test.ResultsCompared with healthy subjects, spastic hemiparetic subjects showed significantly higher intensity with velocity-dependent heterogeneous activation during passive stretch and more lateral and proximal activation distribution during active contraction. In addition, spastic hemiparetic subjects displayed almost non-overlapping activation areas during passive stretch and active contraction. The activation distribution of passive stretch was more distal when compared with the active contraction.ConclusionsThese alterations of the BB activity could be the consequence of deficits in the descending central control after stroke. The complementary spatial distribution of spastic BB activity reflected their opposite motor units (MUs) recruitment patterns between passive stretch and active contraction. This HD-sEMG study provides new neurophysiological evidence for the spatial relationship of spastic BB activity between passive stretch and active contraction, advancing our knowledge on the mechanism of spasticity.Trial registrationChiCTR2000032245.

Efficacy of Physical and Mental Practice in Improving Strength of Biceps Brachi in Youngadults

Efficacy of Physical and Mental Practice in Improving Strength of Biceps Brachi in Youngadults

A portable inflatable soft wearable robot to assist the shoulder during industrial work.

Repetitive overhead tasks during factory work can cause shoulder injuries resulting in impaired health and productivity loss. Soft wearable upper extremity robots have the potential to be effective injury prevention tools with minimal restrictions using soft materials and active controls. We present the design and evaluation of a portable inflatable shoulder wearable robot for assisting industrial workers during shoulder-elevated tasks. The robot is worn like a shirt with integrated textile pneumatic actuators, inertial measurement units, and a portable actuation unit. It can provide up to 6.6 newton-meters of torque to support the shoulder and cycle assistance on and off at six times per minute. From human participant evaluations during simulated industrial tasks, the robot reduced agonist muscle activities (anterior, middle, and posterior deltoids and biceps brachii) by up to 40% with slight changes in joint angles of less than 7% range of motion while not increasing antagonistic muscle activity (latissimus dorsi) in current sample size. Comparison of controller parameters further highlighted that higher assistance magnitude and earlier assistance timing resulted in statistically significant muscle activity reductions. During a task circuit with dynamic transitions among the tasks, the kinematics-based controller of the robot showed robustness to misinflations (96% true negative rate and 91% true positive rate), indicating minimal disturbances to the user when assistance was not required. A preliminary evaluation of a pressure modulation profile also highlighted a trade-off between user perception and hardware demands. Finally, five automotive factory workers used the robot in a pilot manufacturing area and provided feedback.

Effects of radial extracorporeal shock wave therapy on flexor spasticity of the upper limb in post-stroke patients: A randomized controlled trial

Objective This study aimed to assess the efficacy of radial extracorporeal shock wave therapy in treating upper limb spasticity after a stroke. Design Randomized controlled trial. Setting Zhujiang Hospital of Southern Medical University. Subjects This study included 95 people with stroke. Intervention The active (n = 47) and sham-placebo (n = 48) radial extracorporeal shockwave therapy groups received three treatment sessions (every third day). Main measures The Modified Ashworth Scale, Hmax/Mmax ratio, root mean square, co-contraction ratio, mechanical parameters of the muscle and temperature were measured at baseline and days 2, 5 and 8. Results Among the 135 potential participants screened, 100 were enrolled and allocated randomly, with 95 participants ultimately being included in the intent-to-treat analysis dataset. The active group showed significantly better improvements in upper limb spasticity and muscle function than did the sham-placebo group. Greater improvements in the Modified Ashworth Scale were observed in the active group than in the sham-placebo group (difference, −0.45; 95% CI, −0.69 to −0.22; P < 0.001). Moreover, significant differences in root mean square, co-contraction ratio and Hmax/Mmax ratio were observed between the two groups (all P < 0.001). The mechanical parameters of the biceps muscle were significantly better in the active group than in the sham-placebo group (P < 0.001). The active group had a higher temperature than the sham-placebo group, although the difference was not significant (P = 0.070). Conclusions This study revealed that the treatment with extracorporeal shockwave therapy can relieve upper limb spasticity in people with stroke.

Characterization of muscle oxygenation response in well-trained handcyclists.

Peripheral responses might be important in handcycling, given the involvement of smallmusclescompared to other exercise modalities. Therefore, the goal of this study was to compare changes in muscle oxygen saturation (∆SmO2) and deoxyhemoglobin level (∆[HHb]) between different efforts and muscles. Handcyclists participated in a Wingate, a maximal incremental test and a 20-min time-trial (TT). Oxygen uptake (VO2)as well as ∆SmO2, ∆[HHb], deoxygenation and reoxygenation rates in the triceps brachii (TB), biceps brachii (BB), anterior deltoid (AD) and extensor carpi radialis brevis (ER) were measured. ER ∆[HHb]max was 37% greater in the incremental test than in the Wingate (ES = 0.392, P = 0.031). TT mean power (W/kg) was associated with BB ∆SmO2min measured in the incremental test (r = -0.998 [-1.190, -0.806], P = 0.002) and in the Wingate (r = -0.994 [-1.327, -0.661], P = 0.006). MAP (W/kg) was associated with Wingate BB ∆SmO2min (r = -0.983 [-0.999, -0.839], P = 0.003), and Wingate peak (r = 0.649 [0.379, 0.895], P = 0.008) and mean power(W/kg) (r = 0.925 [0.752, 0.972], P = 0.003) was associated with right handgrip force. The strongest physiological predictor for TT performance was BB ∆SmO2min in the incremental test (P = 0.002, r2= 0.993, SEE 0.016W/kg), Wingate BB ∆SmO2min for MAP (P = 0.003, r2= 0.956, SEE 0.058W/kg) and right handgrip force for Wingate peak power (P = 0.005, r2= 0.856, SEE 0.551W/kg). Peripheral aerobic responses (muscle oxygenation) were predictiveof handcycling performance.

Anatomical study of the safety corridor for bridge plating positioned on the lateral border of the humerus.

This study shows the danger zone and the safety corridor in the lateral approach with bridge plating by measuring the distance between the lateral side of the plate positioned on the lateral aspect of the humerus and the radial nerve after it pierces the lateral intermuscular septum, in the different forearm positions. Forty arms of 20 human cadavers were used, the radial nerve was identified and marked on the lateral surface the radial nerve at the exit of the lateral intermuscular septum and anteriorisation of the nerve in relation to the humeral shaft and the lateral epicondyle was also marked. The distances were measured with a digital caliper. A submuscular extraperiosteal corridor was created, proximally between the biceps brachialis and deltoid muscle and distally between the triceps and brachioradialis muscle, followed by the positioning of the low contact large fragments contoured plate with 14 combined holes (fixed and cortical angle), inserted from distal to proximal. Measurements were performed in four positions (elbow flexion with forearm pronation, elbow flexion with forearm supination, elbow extension with forearm pronation and elbow extension with forearm supination). Significant statistical differences occurred with the different positions, and the elbow flexion with forearm supination was shown to be the position that provides the safest submuscular extraperiosteal corridor in a lateral approach of the humerus. The danger zone of radial nerve is an area that extends from 15cm to 5cm proximal to the lateral epicondyle and the safest way to create a submuscular and extraperiosteal corridor in the lateral region of the humerus is with the elbow in flexion and the forearm in supination.

Anatomy of the Lateral Antebrachial Cutaneous Nerve: Landmarks for Procedures in the Cubital Fossa

The research outlines anatomical landmarks that may help surgeons in identifying the lateral antebrachial cutaneous nerve (LABCN) to minimize nerve damage during procedures in the cubital fossa. Twenty-eight fresh cadaveric upper extremities were dissected. The course of the LABCN was followed from the emerging point at the biceps brachii tendon (BT) to the mid-forearm. The nerve's relationships with the BT, lateral epicondyle (LE), antebrachial vein, and brachioradialis (BR) muscle were measured and documented. The LABCN emerged lateral to the BT in all specimens and crossed medially at the top of the BT in 50% of the cadavers. It was deep to the forearm superficial fascia in all cadavers. At the level of the LE, the nerve was located at a mean of 6.3 ± 3.1 mm medial to the BR. The LABCN aligns with the medial border of the BR at a mean of 68 mm distal to the interepicondylar line. The mean distance from the LE to the LABCN at the interepicondylar line was 24.5 ± 7.2 mm. The LABCN and antebrachial vein are in the same deep fascia plane, on average 47.6 ± 5 mm (37-55) from the LE. At the elbow joint level, 82.1% of the specimens have two branches for the LABCN, whereas 17.9% demonstrated only a single branch. Lateral antebrachial cutaneous nerve was situated approximately 6.8 cm distal to the interepicondyle line, positioned at the ulnar edge of the BR, and runs parallel with the antebrachial vein deep to the forearm fascia plane. The nerve crossed over the biceps tendon in 50% of the specimens. These findings suggest that the nerve should be identified 6-7 cm distal to the LE, followed by a proximal dissection. This study may help surgeons in identifying LABCN, and reducing the potential risk of LABCN injury.

Electromyographic Analysis of Upper- and Lower-extremity Muscles in Adults during Agro-healing Activities

This study investigated the activity of upper- and lower-extremity muscles for 15 agricultural tasks of agro-healing. For the development of an agro-healing program using farm resource types, 15 selected agro-healing activities (namely, digging, raking, fertilizing, planting transplants, tying plants to stakes, watering, harvesting, washing, cutting, cooking, collecting natural objects, decorating natural objects, interacting with dogs, walking dogs, and feeding fish) were extracted and performed in a total of 21 adults (average age: 42.29 ± 14.76 years) at D Care Farm in Cheongju, Korea, from June to July 2022. Before these activities, informed consent was obtained from participants and muscle activity of the upper and lower extremities was measured. Muscle activation during activity performance was measured using electromyography (EMG), and the rating of perceived exertion for each activity was investigated. Bipolar surface EMG electrodes were attached at 16 locations on the left and right upper-extremity muscles (anterior deltoid, biceps brachialis, brachioradialis, and flexor carpi ulnaris) and lower-extremity muscles (vastus lateralis, vastus medialis, biceps femoris, and gastrocnemius). The results indicated that the activity of the lower-extremity muscles was higher than that of the upper-extremity muscles during 15 agricultural activities. During plant-mediated activity and animal-assisted activities, the rate of right muscle use was higher than that of left muscle use among the upper-extremity muscles, whereas the rate of right and left muscle use showed a similar tendency among the lower-extremity muscles. During plant-mediated activities, agricultural activities involving the use of heavy tools highly activated the right forearm muscle (flexor carpi ulnaris), whereas holding and interacting with animals highly activated the left forearm muscles (biceps brachialis, brachioradialis, and flexor carpi ulnaris). It is expected that the EMG data obtained in this study can be used as basic biomechanical data when designing an agro-healing program to improve physical function.

Synaptic inputs to motor neurons underlying muscle coactivation for functionally different tasks have different spectral characteristics.

The central nervous system (CNS) may produce the same endpoint trajectory or torque profile with different muscle activation patterns. What differentiates these patterns is the presence of cocontraction, which does not contribute to effective torque generation but allows to modulate joints' mechanical stiffness. Although it has been suggested that the generation of force and the modulation of stiffness rely on separate pathways, a characterization of the differences between the synaptic inputs to motor neurons (MNs) underlying these tasks is still missing. In this study, participants coactivated the same pair of upper-limb muscles, i.e., the biceps brachii and the triceps brachii, to perform two functionally different tasks: limb stiffness modulation or endpoint force generation. Spike trains of MNs were identified through decomposition of high-density electromyograms (EMGs) collected from the two muscles. Cross-correlogram showed a higher synchronization between MNs recruited to modulate stiffness, whereas cross-muscle coherence analysis revealed peaks in the β-band, which is commonly ascribed to a cortical origin. These peaks did not appear during the coactivation for force generation, thus suggesting separate cortical inputs for stiffness modulation. Moreover, a within-muscle coherence analysis identified two subsets of MNs that were selectively recruited to generate force or regulate stiffness. This study is the first to highlight different characteristics, and probable different neural origins, of the synaptic inputs driving a pair of muscles under different functional conditions. We suggest that stiffness modulation is driven by cortical inputs that project to a separate set of MNs, supporting the existence of a separate pathway underlying the control of stiffness.NEW & NOTEWORTHY The characterization of the pathways underlying force generation or stiffness modulation are still unknown. In this study, we demonstrated that the common input to motor neurons of antagonist muscles shows a high-frequency component when muscles are coactivated to modulate stiffness but not to generate force. Our results provide novel insights on the neural strategies for the recruitment of multiple muscles by identifying specific spectral characteristics of the synaptic inputs underlying functionally different tasks.

Neuromechanical Differences between Pronated and Supinated Forearm Positions during Upper-Body Wingate Tests.

Arm-cycling is a versatile exercise modality with applications in both athletic enhancement and rehabilitation, yet the influence of forearm orientation remains understudied. Thus, this study aimed to investigate the impact of forearm position on upper-body arm-cycling Wingate tests. Fourteen adult males (27.3 ± 5.8 years) underwent bilateral assessments of handgrip strength in standing and seated positions, followed by pronated and supinated forward arm-cycling Wingate tests. Electromyography (EMG) was recorded from five upper-extremity muscles, including anterior deltoid, triceps brachii lateral head, biceps brachii, latissimus dorsi, and brachioradialis. Simultaneously, bilateral normal and propulsion forces were measured at the pedal-crank interface. Rate of perceived exertion (RPE), power output, and fatigue index were recorded post-test. The results showed that a pronated forearm position provided significantly (p < 0.05) higher normal and propulsion forces and triceps brachii muscle activation patterns during arm-cycling. No significant difference in RPE was observed between forearm positions (p = 0.17). A positive correlation was found between seated handgrip strength and peak power output during the Wingate test while pronated (dominant: p = 0.01, r = 0.55; non-dominant: p = 0.03, r = 0.49) and supinated (dominant: p = 0.03, r = 0.51; don-dominant: p = 0.04, r = 0.47). Fatigue changed the force and EMG profile during the Wingate test. In conclusion, this study enhances our understanding of forearm position's impact on upper-body Wingate tests. These findings have implications for optimizing training and performance strategies in individuals using arm-cycling for athletic enhancement and rehabilitation.

Biceps tendon autograft augmentation for rotator cuff and instability procedures: a narrative review.

Rotator cuff tears (RCT) and instability are the most common surgically treated shoulder pathologies. The concept of augmentation using the long head of the biceps tendon (LHBT) autograft was created to improve the results of surgical treatment of these pathologies, especially in cases of chronic and massive injuries. The popularity of using the LHBT for augmentation is evidenced by the significant number of publications on this topic published in the last 3 years; however, only one systematic review has been published regarding only LHBT augmentation for massive RCTs. Several studies comparing partial repair with partial repair and additional LHBT augmentation for RCT showed superior clinical outcomes and lower re-tear rates when LHBT augmentation was performed. There is a rising popularity of using LHBT as an autograft to perform superior capsule reconstruction (SCR) in case of irreparable rotator cuff tears. In recent years, shoulder stabilization by arthroscopic Bankart repair with biceps augmentation has been promoted with very promising short-term results. The evidence provided by studies appears to be sufficient to recommend the use of LHBT for augmentation whenever necessary; however, larger studies with long-term follow-up are needed.