Triceps Research Articles

Effect of speed and leading or trailing limbs on surface muscle activities during canter in Thoroughbred horses.

Given that Thoroughbred horses' canter is an asymmetric gait, not only speed but also leading or trailing limbs could affect muscle activities. However, the muscle activity during a canter remains poorly understood. Hence, we aimed to investigate speed and lead-side (leading or trailing) effects on surface electromyography (sEMG) during a canter. The sEMG data were recorded from left Musculus brachiocephalicus (Br), M. infraspinatus (Inf), long head of M. triceps brachii (TB), M. gluteus medius (GM), M. semitendinosus (ST), and M. flexor digitorum longus of seven Thoroughbreds with hoof-strain gauges at the left hooves. Horses cantered on a flat treadmill at 7, 10, and 13 m/s for 25 s each without lead change. Subsequently, the horses trotted for 3 min and cantered at the same speed and duration in the opposite lead side ("leading" at the left lead and "trailing" at the right lead). The order of the lead side and speed was randomized. The mean of 10 consecutive stride durations, duty factors, integrated-EMG values (iEMG) for a stride, and muscle onset and offset timing were compared using a generalized mixed model (P < 0.05). Stride durations and duty factors significantly decreased with speed regardless of the lead side. In all muscles, iEMG at 13 m/s significantly increased compared with 7 m/s (ranging from +15% to +134%). The lead-side effect was noted in the iEMG of Br (leading > trailing, +47%), Inf (leading > trailing, +19%), GM (leading < trailing, +20%), and ST (leading < trailing, +19%). In TB, GM, and ST, muscle onset in trailing was earlier than the leading, while offset in the leading was earlier in Br. In conclusion, different muscles have different responses to speed and lead side; thus, both the lead side and running speed should be considered during training and/or rehabilitation including canter or gallop.

Association of myostatin gene polymorphism with echocardiographic and muscular ultrasonographic measurements in Hungarian thoroughbreds horses

The g.66493737C/T polymorphism of the myostatin gene (MSTN) majorly influences muscle fiber composition and best race distance of Thoroughbreds. Thus, a better understanding of this process may lead to superior genetic exploitation for maximizing Thoroughbred athletic potential.Our objective is to investigate whether myostatin genotypes are associated with muscular development and cardiac variables of Thoroughbreds. Echocardiography and muscular ultrasonography were performed on three groups having C/C, C/T, and T/T genotypes, respectively. Each group consisted of 22 animals. Homogeneity of variance between the groups was checked by Levene's test. Multivariate analysis of variance was applied to determine differences in measured variables vs. MSTN genotypes. Fascicle length of anconeus and thickness of triceps brachii muscles showed significant differences between C/C and T/T genotypes (pFascicle-length-of-anconeus = 0.004, pthickness-of-triceps-brachii < 0.001). According to the primary outcome, there are associations between myostatin genotypes and cardiac variables. Aortic diameter at the sinus of Valsalva (end-diastole and end-systole) and aortic diameter at the valve (end-systole) indicated significant differences between C/C and T/T genotypes (paortic-diameter-at-the-sinus-of-Valsalva-end-diastole = 0.015, paortic-diameter-at-the-sinus-of-Valsalva-end-systole = 0.011, paortic-diameter-at-the-valve-end-systole = 0.014). Pearson correlation effect sizes were rFascicle-length-of-anconeus = 0.460, rthickness-of-triceps-brachii = 0.590, raortic-diameter-at-the-sinus-of-Valsalva-end-diastole = 0.423, raortic-diameter-at-the-sinus-of-Valsalva-end-systole = 0.450, and raortic-diameter-at-the-valve-end-systole = 0.462. C/C genotypes gave 22.1, 12.2, 6.3, 6.0, and 6.7% higher values compared to T/T genotypes, respectively. Differences regarding aortic diameter between genotype groups support the hypothesis that C/C animals have consequently increased cardiac output and aerobic capacity.

Electromyographic and Kinematic Comparison of the Leading and Trailing Fore- and Hindlimbs of Horses during Canter.

This study compared muscle activity and movement between the leading (Ld) and trailing (Tr) fore- (F) and hindlimbs (H) of horses cantering overground. Three-dimensional kinematic and surface electromyography (sEMG) data were collected from right triceps brachii, biceps femoris, middle gluteal, and splenius from 10 ridden horses during straight left- and right-lead canter. Statistical parametric mapping evaluated between-limb (LdF vs. TrF, LdH vs. TrH) differences in time- and amplitude-normalized sEMG and joint angle-time waveforms over the stride. Linear mixed models evaluated between-limb differences in discrete sEMG activation timings, average rectified values (ARV), and spatio-temporal kinematics. Significantly greater gluteal ARV and activity duration facilitated greater limb retraction, hip extension, and stifle flexion (p < 0.05) in the TrH during stance. Earlier splenius activation during the LdF movement cycle (p < 0.05), reflected bilateral activation during TrF/LdH diagonal stance, contributing to body pitching mechanisms in canter. Limb muscles were generally quiescent during swing, where significantly greater LdF/H protraction was observed through greater elbow and hip flexion (p < 0.05), respectively. Alterations in muscle activation facilitate different timing and movement cycles of the leading and trailing limbs, which justifies equal training on both canter leads to develop symmetry in muscular strength, enhance athletic performance, and mitigate overuse injury risks.

Radial nerve palsy caused by a rapidly growing intramuscular hematoma in an infant with biliary atresia: a case report

BackgroundBiliary atresia (BA) is a rare cause of persistent jaundice in infants that can result in vitamin K malabsorption and vitamin K deficiency bleeding (VKDB). We present an infant with BA who developed a rapidly growing intramuscular hematoma in her upper arm after a vaccination which caused a radial nerve palsy.Case presentationAn 82-day-old girl was referred to our hospital because of a rapidly growing left upper arm mass. She had received three doses of oral vitamin K before age 1 month. At age 66 days, she received a pneumococcal vaccination in her left upper arm. On presentation, she showed no left wrist or finger extension. Blood examination revealed direct hyperbilirubinemia, liver dysfunction, and coagulation abnormalities, indicating obstructive jaundice. Magnetic resonance imaging showed a hematoma in the left triceps brachii. Abdominal ultrasonography revealed an atrophic gallbladder and the triangular cord sign anterior to the portal vein bifurcation. BA was confirmed on cholangiography. VKDB resulting from BA in conjunction with vaccination in the left upper arm were considered the cause of the hematoma. The hematoma was considered the cause of her radial nerve palsy. Although she underwent Kasai hepatic portoenterostomy at age 82 days, the obstructive jaundice did not sufficiently improve. She then underwent living-related liver transplantation at age 8 months. The wrist drop was still present at age 1 year despite hematoma resolution.ConclusionsDelayed detection of BA and inadequate prevention of VKDB can result in permanent peripheral neuropathy.

Muscle Hypertrophy Responses to Changes in Training Volume: A Retrospective Analysis.

This study assessed associations between changes in the weekly number of sets performed and the percentage change in muscle thickness of the biceps (MTBB) and triceps (MTTB) brachii muscles. Through a retrospective analysis, sixty-eight resistance-trained subjects that participated in previous studies had their previous training volumes analyzed and compared to the volume imposed during each individual study. The relationship between variables was determined through Spearman correlation and a k-cluster analysis was performed to subdivide the participants into three groups and classified as:<0%; 0-50%, and >50% increase in the number of sets for both muscle groups. Moderate and weak correlations were observed between the alterations in training volume and changes in MTBB (rs=0.44, p=0.001) and MTTB (rs=0.35, p=0.002), respectively. A significant difference was noted between<0% to >50% for MTBB and MTTB (p=0.017; p=0.042, respectively), while no significant difference was observed between<0% to 0-50% and 0-50% to >50% (both p >0.05) for both muscle groups. In conclusion, muscle hypertrophy of the upper limbs is only weakly to moderately associated with changes in training volume of trained subjects.

Teaching NeuroImage: Radial Compression Neuropathy Secondary to Accessory Belly of the Triceps Muscle.

Teaching NeuroImage: Radial Compression Neuropathy Secondary to Accessory Belly of the Triceps Muscle.

Giant Malignant Schwannoma in the Right Thoracic Limb: Case Report

Introduction: Tumors of the sheath of the peripheral nerves, also known as schwannomas, mainly benign. The malignancy of these is very rare and there are few cases reported in the literature. Clinical case: A 62-year-old male with a diagnosis of ulcerated malignant schwannoma in the distal third of the posterior aspect of the right thoracic limb who attended the oncosurgery service. The CT scan reported a large solid tumor, predominantly hypodense, with a probable origin dependent on the poorly defined triceps brachii muscle. Surgical removal was performed with two centimeters of perilesional margins, performing primary closure with drain placement. Conclusion: Surgical treatment of total surgical removal with adequate margin coverage is the treatment of choice as a protective factor in survival in this type of tumor..

Association of functional sequence variants of the myosin heavy chain 3 gene with muscle collagen content in pigs.

This study examined the association between functional sequence variants (FSVs) of myosin heavy chain 3 (MYH3) genotypes and collagen content in a Landrace and Jeju native pig (JNP) crossbred population. Four muscles (Musculus longissimus dorsi, Musculus semimembranosus, Musculus triceps brachii, and Musculus biceps femoris) were used for the analysis of meat collagen content, and the same animals were genotyped for the FSVs of the MYH3 gene by using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Three FSVs of MYH3 genotypes were identified and had genotype frequencies of 0.358, 0.551, and 0.091 for QQ, Qq, and qq, respectively. QQ animals for the FSVs of the MYH3 genotypes showed higher collagen content in their M. longissimus dorsi (p < 0.001), M. semimembranosus (p < 0.001), M. triceps brachii (p < 0.001), and M. biceps femoris (p < 0.001) than qq homozygous animals. After the validation of this result in other independent populations, the FSVs of MYH3 genotypes can be a valuable genetic marker for improving collagen content in porcine muscles and can also be applied to increase the amount of collagen for biomedical purposes.

The medial forearm fascia and lateral forearm fascia contribute to overhead elbow extension in displaced olecranon fractures: a biomechanical study.

In nonoperative management of displaced olecranon fractures, patients are able to maintain overhead extension despite a persistent nonunion. It has been hypothesized that this is feasible because of an intact lateral cubital retinaculum. The purpose of this biomechanical study was to determine the contribution of the medial and lateral cubital retinacula to overhead extension in the setting of a displaced olecranon fracture. Eight fresh-frozen cadaveric upper-extremity specimens were used in this study. The triceps muscle was loaded through a pulley system operated by an Instron 8874 Biaxial Servohydraulic Fatigue Testing System at a rate of 10 mm/second to simulate overhead elbow extension. Each specimen was tested in 4 states: (1) native state with an intact olecranon; (2) transverse olecranon fracture; (3) transection of 1 cubital retinaculum (medial or lateral); and (4) transection of both medial and lateral cubital retinacula. The primary outcome was the ability to perform overhead extension. The secondary outcome was the force needed to generate extension. Elbow extension was noted in each specimen for trials 1, 2, and 3. Only when both the lateral fascia and medial fascia were transected was elbow extension not achieved. There was no significant difference in the force required to generate extension in the first 3 trials (P=.99). There was no significant difference in the change in the maximum force required to achieve extension between the specimens with only the medial side transected and the specimens with only the lateral side transected (P=.07). In the setting of an olecranon fracture, this biomechanical study suggests that if either the lateral or medial cubital retinaculum remains in continuity with the distal ulna, active overhead extension can be maintained. This finding may explain the positive clinical outcomes of nonoperative management of displaced olecranon fractures in the elderly patient population. Determining the integrity of the fascial structures preoperatively may help select candidates for nonoperative treatment of displaced olecranon fractures.

Evidence of a Double Pulse Muscle Activation Strategy in Drummers’ Trunk and Upper Limb Muscles During High-velocity Cymbal Crashes

Background: Playing the drum kit is a physically and cognitively demanding task, and skilled drummers share many such attributes with elite athletes. The ‘double pulse’ muscle activation (DPMA) pattern is a motor control strategy that has been observed in athletes of sports involving ballistic movements (e.g., baseball, golf, Mixed Martial Arts), and is believed to function to increase force transfer to the target. Objective: This study examined the muscle activation patterns of highly skilled drummers for evidence of a DPMA during high-velocity cymbal crashes. Methods: Five drummers were instrumented with electromyography electrodes on the right latissimus dorsi, triceps brachii, erector spinae, rectus abdominis, deltoideus posterior (DP), teres major, extensor carpi radialis, and flexor carpi ulnaris muscles. Six trials of data were collected, including a resting baseline, three maximum voluntary exertions (MVE) consisting of maximal effort cymbal crashes, a drumming pattern that included multiple crashes, and a ‘free-play’ trial. Results: The DPMA waveform was observed in all trials, but only those observed during the MVE trials were confirmed to coincide with the crashing movement via video analysis. The DP muscle – which functions to extend the shoulder joint to crash the stick on to the cymbal – exhibited confirmed DPMAs the most frequently. Conclusion: The extent to which drummers use the DPMA to produce high-velocity cymbal crashes within authentic playing conditions is inconclusive and needs further examination. Future study of the DPMA phenomenon in drummers would benefit from the addition of 3-dimensional motion capture to further understand the purpose of the muscle contractions of the DPMA.

필라테스 기구 운동 시 포지션에 따른 손목 과신전 자세가 상지와 어깨 근 활성도 및 통증에 미치는 영향

Purpose: This study compares and analyzes the effects of wrist hyper-extension posture on muscle activity and pain in upper limbs and shoulders when applying the Pilates exercise program to healthy adult women.BR Methods: The participants repeated hyper-extension posture and neutral posture of the wrist three times each using three instruments (cadillac, reformer, barrel). The activities of upper limbs muscles (post deltoid, anterior deltoid, lateral triceps, biceps brachii, and extensor carpi radialis brav is) were measured using surface electromyography. The pains of upper limbs (median wrist, lateral wrist, lateral elbow, and upper shoulder) were measured using electro algometer (FPX25).BR Result: The hyper-extension posture of the wrist revealed significant differences activities of post deltoid, lateral triceps, biceps brachii and extensor carpi radialis bravis muscles compared to neutral position of the wrist (p.05).BR The hyper-extension posture of the wrist elicited pain on median wrist, lateral wrist, lateral elbow, and upper shoulder more earlier that neutral posture of the wrist significantly (p.05).BR Conclusion: The hyper-extension posture of the wrist during the Pilates exercise program can reduce muscle activities and elicited pain on the upper limbs. Neutral posture of the wrist is important to improve muscle activities and reduce pain.

Vasculogenic Myoclonus of Peripheral Origin after Whiplash Injury: A Case Report

Based on the neuroanatomical origin of the electrical discharge, myoclonus could be classified in terms of its etiology as cortical, subcortical, spinal, or peripheral. A 29-year-old female patient experienced a continuous involuntary rhythmic twitching movement of the right elbow for 6 months. This myoclonus occurred immediately after a whiplash injury caused by a rear-end car accident. The patient had no radiological, clinical, or electrophysiological evidence for central nervous system origin. Concentric needle electromyography recordings of the right biceps, brachioradialis, and triceps muscles presented bursts of spontaneous rhythmic activity synchronous to the clinical myoclonus. Doppler ultrasound on the right arm revealed that the biceps and triceps contraction coincided with the vascular pulsation of the brachial artery and vein. This result suggested that myoclonus was caused by vascular stimulation, similar to the pathophysiology of hemifacial spasms. A whiplash injury around the neck or arm may have affected the vascular structures in the upper and middle trunks, resulting in vasculogenic myoclonus. Electromyography can be used to determine the classification and distribution of myoclonic jerks.

The interaction between changes of muscle activation and cortical network dynamics during isometric elbow contraction: a sEMG and fNIRS study.

Objective: The relationship between muscle activation during motor tasks and cerebral cortical activity remains poorly understood. The aim of this study was to investigate the correlation between brain network connectivity and the non-linear characteristics of muscle activation changes during different levels of isometric contractions. Methods: Twenty-one healthy subjects were recruited and were asked to perform isometric elbow contractions in both dominant and non-dominant sides. Blood oxygen concentrations in brain from functional Near-infrared Spectroscopy (fNIRS) and surface electromyography (sEMG) signals in the biceps brachii (BIC) and triceps brachii (TRI) muscles were recorded simultaneously and compared during 80% and 20% of maximum voluntary contraction (MVC). Functional connectivity, effective connectivity, and graph theory indicators were used to measure information interaction in brain activity during motor tasks. The non-linear characteristics of sEMG signals, fuzzy approximate entropy (fApEn), were used to evaluate the signal complexity changes in motor tasks. Pearson correlation analysis was used to examine the correlation between brain network characteristic values and sEMG parameters under different task conditions. Results: The effective connectivity between brain regions in motor tasks in dominant side was significantly higher than that in non-dominant side under different contractions (p < 0.05). The results of graph theory analysis showed that the clustering coefficient and node-local efficiency of the contralateral motor cortex were significantly varied under different contractions (p < 0.01). fApEn and co-contraction index (CCI) of sEMG under 80% MVC condition were significantly higher than that under 20% MVC condition (p < 0.05). There was a significant positive correlation between the fApEn and the blood oxygen value in the contralateral brain regions in both dominant or non-dominant sides (p < 0.001). The node-local efficiency of the contralateral motor cortex in the dominant side was positively correlated with the fApEn of the EMG signals (p < 0.05). Conclusion: In this study, the mapping relationship between brain network related indicators and non-linear characteristic of sEMG in different motor tasks was verified. These findings provide evidence for further exploration of the interaction between the brain activity and the execution of motor tasks, and the parameters might be useful in evaluation of rehabilitation intervention.

Myalgia in a Patient with Adult-Onset Asthma with Periocular Xanthogranuloma (AAPOX) due to Myotonic Dystrophy type 2 (P6-8.013)

<h3>Objective:</h3> To report a patient with myotonic dystrophy type 2 (DM2) and an adult-onset asthma with periocular xanthogranuloma (AAPOX). <h3>Background:</h3> AAPOX is a rare systemic non-Langerhans histiocytosis, clinically characterized by periocular yellowish plaques, adult-onset asthma, and lymphadenopathy, and pathologically characterized by non-caseating granulomas consisting of foamy histiocytes and Touton giant cells. The etiology of AAPOX is unknown, but recent studies suggested a possible link to IgG4-related disease. Autoimmune diseases occur in up to 30% of myotonic dystrophy type 2 (DM2) patients but concomitant AAPOX and DM2 have never been reported. <h3>Design/Methods:</h3> Case report. <h3>Results:</h3> A 38-year-old man with hyperlipidemia presented with 1.5-year history of progressive bilateral periorbital swelling and periocular yellowish plaques, 1-year history of asthma and exercise intolerance, and 4-month history of rosuvastatin-associated myalgias and difficulty climbing stairs. Periorbital soft tissue biopsy revealed characteristic pathological features of AAPOX. Neurologic examination revealed neither weakness nor clinical myotonia. Family history was significant for bradyarrhythmia requiring pacemaker in his mother and maternal grandfather. The patient’s creatine kinase was elevated at 606 U/L (normal &lt; 308 U/L). HMGCR-IgG was negative. IgG4 level was normal. Electromyography revealed diffuse myotonic discharges and a mild proximal myopathy without fibrillation potentials. A triceps brachii biopsy showed a marked increase of fibers harboring internal nuclei, scattered pyknotic nuclear clumps, and type 1 fiber smallness without granulomas. Genetic testing revealed a heterozygous CCTG repeat expansion &gt; 15,600 base pairs in intron 1 of <i>CNBP</i>, consistent with a diagnosis of DM2. His cardiac evaluation was unrevealing. The patient was treated with prednisone and methotrexate with improvement of his periocular disease. Myalgias persisted despite discontinuation of rosuvastati <h3>Conclusions:</h3> We first report the cooccurrence of AAPOX and DM2. Our finding supports the increased risk of autoimmune diseases in DM2 patients. <b>Disclosure:</b> Dr. Skolka has nothing to disclose. The institution of Shreyasee Amin has received research support from NIH. Dr. Liewluck has nothing to disclose.

Late integration of vision and proprioception during perturbed reaches.

The motor system corrects rapidly, but selectively, for perturbations to ongoing reaching movements, depending on the constraints of the task. To account for such sophistication, it has been postulated that corrections are based on an estimated limb state that integrates all sensory changes caused by the perturbation, taking into account their processing delays. Here, we asked if information from different sensory modalities is integrated immediately or processed separately in the early phase of a response. We perturbed the estimated state of the limb with both unimodal and bimodal visual and proprioceptive perturbations without changing the actual limb state. For visual perturbations, a cursor representing the hand was shifted to the left or the right relative to the true hand location. For proprioceptive perturbations, the biceps or triceps muscles were vibrated, which induced illusory limb-state changes to the right or the left. In the bimodal condition, the perturbations to vision and proprioception were either congruent or incongruent in their directions. Response latencies show that it takes ∼100 ms longer to respond to unimodal visual perturbations than to unimodal proprioceptive perturbations. Responses to bimodal perturbations show that it takes an additional ∼100 ms beyond the response to unimodal visual perturbations for intermodal consistency to impact the response. These results suggest that visual and proprioceptive signals are initially processed separately for state estimation and only combined at the level of the limb's motor output, instead of being immediately integrated into a single state estimate of the limb.NEW & NOTEWORTHY Both visual and proprioceptive signals provide information about arm state during reaching. By perturbing the perceived, but not the actual, position of the hand in both modalities using visual disturbances and muscle vibration, we examined multimodal integration and state estimation during reaching. Our results suggest that the early reach corrections are based on separate state estimates from the two sensory modalities and only later are based on a combined state estimate.

Comparison of Muscle Activity between the Horizontal Bench Press and the Seated Chest Press Exercises Using Several Grips.

This study aims to compare muscle activity in the pectoralis major, anterior deltoid, and triceps brachii in the horizontal bench press exercise with a prone grip at 150% and 50% of the biacromial width and the seated chest press exercise with two types of grips (a neutral grip at ~150% of the biacromial width and a prone grip at ~200% of the biacromial width). Twenty physically active adults performed a set of 8 repetitions at 60% of the one repetition maximum. The results showed that the clavicular portion of the pectoralis major had significantly greater muscle activity in the seated chest press exercise with a neutral grip (~30% of the maximal voluntary isometric contraction (MVIC)) than in the lying bench press exercise with a prone grip at 150% of the biacromial width (~25% MVIC). The muscle activity of the anterior deltoid was not significantly different across any exercise or grip evaluated (~24% MVIC). The muscle activity of the triceps brachii was significantly higher in the lying bench press exercise with a grip at 50% biacromial width (~16% MVIC) than at 150% of the biacromial width (~12% MVIC). In conclusion, all exercises and grips showed similar muscle activity, and the selection of these exercises should not be based exclusively on the grounds of muscle activation but rather on the load capacity lifted, the level of technique of the participant, and/or the transference to the specific sporting discipline or event.

The effect of pre-slaughter electrical stunning on bleeding efficiency, meat quality, histology, and microbial count of several goat muscles

This study was designed to compare the effect of non-electrical stunning and electrical stunning on bleeding efficiency, meat quality characteristics, bacterial count, and histology of longissimus thoraces, semitendinosus, biceps femoris, infraspinatus, semimembranosus, and triceps brachii muscles of goats. Forty goats were randomly divided into two groups: electrical stunning and non-electrical stunning with 20 animals each. Low frequency head-only electrical stunning of 1 Amp for 3 s at a frequency of 50 Hz was used. The slaughter was performed by severing the carotid artery, jugular vein, trachea, and oesophagus. Six muscles were kept in a chiller at 3–4 ºC for 24 h before quality measurements. Samples from the infraspinatus, longissimus thoraces, and semitendinosus muscles were preserved to evaluate histological features. Muscle samples from the non-electrical stunning group had substantially higher blood loss and lower bacterial counts after 72 h across the six muscles compared to the electrical stunning group. No significant differences in meat quality parameters were evident between the two groups. The stained sections of the electrically-stunned muscle samples detected alteration phenomena due to the presence of muscle fibres with split myofibres and myofibres with central rather than peripheral nuclei. Electrical stunning prior to slaughter increased bacterial contamination, decreased blood loss, and altered the position of muscle nuclei.

Muscular morphometric study of the canine shoulder for the design of 3D-printed endoprostheses in dogs with osteosarcoma of the proximal humerus: a pilot cadaveric study by MRI.

Osteosarcoma frequently affects the proximal humerus in dogs. In veterinary medicine, no therapeutic option for the treatment of osteosarcoma satisfactorily preserves limb function. 3D-printed personalized endoprosthesis offers a promising treatment option. Morphometric data, necessary for the design of the endoprosthesis, are currently lacking in canine patients. Our objective was to acquire the morphometric data necessary to refine the design of the endoprosthesis. A single canine cadaveric thoracic limb. Sagittal proton-density, and sagittal, dorsal, and transverse T1-weighted sequences of the thoracic limb were acquired with a 1.5 Tesla Magnetic Resonance Imaging (MRI) unit. Nineteen muscles of interest were subsequently identified using medical imaging software (Mimics©) and their volume was reconstructed in 3D using computer-aided design (CATIA©). Mormophetric data were recorded for each of the 19 muscles. The same canine cadaver was then dissected to measure the same parameters. All muscles were successfully identified with data consistent with the dissected cadaveric data. Certain muscles were more challenging to isolate on MRI, namely the heads of the triceps brachii, superficial pectoral, and latissimus dorsi. The relative distribution of muscle volumes was similar to historical data. Muscle tissue density was not significantly affected by freezing (1.059 g/cm3). MRI is a useful tool to collect morphometric data but imperfect if used alone. This approach was the first attempt to validate more general morphometric data that could be used to refine the design of custom 3D-printed prostheses for limb-sparing of the proximal humerus. Further imaging studies are warranted to refine our model.

The role of anticipatory and reflexive compensatory muscle activation in catching errors under load uncertainty.

This experiment investigated the role of anticipatory and reflexive compensatory neuromotor control in catching errors occurring under load uncertainty. Participants performed 64 trials of a one-handed ball catching task using visually identical balls of four different weights without knowing the weight of the ball on each trial. Anticipatory and reflexive compensatory muscle activation were recorded in five muscles (anterior deltoid, biceps brachii, wrist flexors group, triceps brachii, lumbar erector spinae) using the EMG integral. In each muscle, the anticipatory and reflexive compensatory muscle activation were compared between successful catches and catching errors for the lightest ball and the heaviest ball. Anticipatory muscle activation was not implicated in errors made with the lightest ball. However, reflexive compensatory muscle activation in the anterior deltoid, biceps brachii, and wrist flexors were implicated in errors made with the lightest ball. Specifically, catching errors with the lightest ball were characterized by elevated reflexive compensatory muscle activation. In the case of the heaviest ball, both anticipatory (anterior deltoid, wrist flexors) and reflexive compensatory muscle activation (anterior deltoid, biceps brachii, wrist flexors) were implicated in catching errors. That is, catching errors with the heaviest ball were characterized by lower anticipatory and reflexive compensatory muscle activation. Results are considered in the context of the likely influence of limb compliance in catching under load uncertainty.

High-intensity training with short and long intervals regulate cortical neurotrophic factors, apoptosis markers and chloride homeostasis in rats with stroke

Background/purposeThe optimal endurance exercise parameters remain to be defined to potentiate long-term functional recovery after stroke. We aim to assess the effects of individualized high-intensity interval training (HIIT) with either long or short intervals on neurotrophic factors and their receptors, apoptosis markers and the two-main cation-chloride cotransporters in the ipsi- and contralesional cerebral cortices in rats with cerebral ischemia. Endurance performance and sensorimotor functions were also assessed MethodsRats with a 2 h transient middle cerebral artery occlusion (tMCAO) performed work-matched HIIT4 (intervals: 4 min) or HIIT1 (intervals: 1 min) on treadmill for 2 weeks. Incremental exercises and sensorimotor tests were performed at day 1 (D1), D8, and D15 after tMCAO. Molecular analyses were achieved in both the paretic and non-paretic triceps brachii muscles and the ipsi- and contralesional cortices at D17 ResultsGains in endurance performance are in a time-dependent manner from the first week of training. This enhancement is supported by the upregulation of metabolic markers in both triceps brachii muscles. Both regimens alter the expression of neurotrophic markers and chloride homeostasis in a specific manner in the ipsi- and contralesional cortices. HIIT acts on apoptosis markers by promoting anti-apoptotic proteins in the ipsilesional cortex ConclusionHIIT regimens seem to be of clinical relevance in the critical period of stroke rehabilitation by strongly improving aerobic performance. Also, the observed cortical changes suggest an influence of HIIT on neuroplasticity in both ipsi- and contralesional hemispheres. Such neurotrophic markers might be considered as biomarkers of functional recovery in individuals with stroke.