Muscle Shortening Research Articles

#2080 Prevalence and development of sarcopenia in chronic hemodialysis patients, a single center, prospective, observational study

Abstract Background and Aims Sarcopenia is a progressive muscle disease (muscle failure) associated with age and various factors including chronic kidney disease that increases the risk of falls, fractures, and mortality. We aimed to analyze the prevalence of sarcopenia and other related problems, such as nutrition or physical fitness, in a group of patients in a chronic dialysis program. Method In our dialysis center, we conducted a prospective observational study to monitor the prevalence and development of sarcopenia. We performed repeated SARC-F (simple five-item questionnaire), grip strength, bioimpedance analysis of body composition, short physical performance battery (SPPB), muscle sonography and MNA (Mini Nutritional Assessment) in chronic hemodialysis patients. Here we report the cross-sectional results of the prevalence of probable sarcopenia (according to the recommendations, enough to trigger assessment of causes and start intervention) defined by EWGSOP2 (the European Working Group on Sarcopenia in Older People), risk of malnutrition, physical fitness, and its development in 1 year follow up. Results The median age in our cohort was 64 years (IQR 16.5). We examined 58 patients (36 men and 22 women) who signed informed consent in the period from 1 October 2020 to 31 January 2023. The prevalence of probable sarcopenia was 20.7%. A higher prevalence was observed in women than in men (27.3% vs 16.7%, P = 0.505), in patients ≥65 years than in the <65 years (26.5% vs 8.3%, P = 0.102) and in the group of patients more than one year on dialysis compared to the group up to one year (27.8% vs 4.5%, P = 0.039). We observed reduced physical performance (SPPB test) in 20 subjects (34.5%) and risk of malnutrition according to MNA in 33 subjects (56.9%). Seven of 29 evaluated patients (24.1%) had a worsening of physical performance (SPPB) after one year. Ten out of 29 patients (34.5%) had worsened MNA scores; the prevalence of malnutrition risk in this group remained the same (51.7%). The development of other parameters did not lead to significant conclusions, given the heterogeneity of characteristics and the relatively small number of subjects. Conclusion Sarcopenia is a serious and potentially impactful problem. The prevalence of probable sarcopenia in our cohort was 20.7% and was higher, although not statistically significant, in women, in patients ≥65 years of age and in patients more than one year on dialysis.

Effects of Manual Lymphatic Drainage with Mobilization and Myofascial Release on Muscle Activities during Dynamic Balance in Adults with Calf Muscle Shortening.

Mobilization with movement (MWM) and myofascial release (MFR) are treatment techniques that increase ankle dorsiflexion range of motion (DFROM). Manual lymphatic drainage (MLD) facilitates waste drainage and improves soft tissue tension in peripheral tissues. To date, no studies have investigated how the combination of MLD, MWM, and MFR influences the human body. The purpose of this study is to determine how the combination of MLD, MWM, and MFR affects DFROM and balance ability. We randomly assigned 16 individuals (26 feet) to one of three groups: MWM-MFR (MR), MWM-MLD (MD), or MWM-MFR-MLD (MRD) intervention. To confirm the intervention effect of each group, DFROM was assessed using a modified lunge test, and dynamic balance was measured using a modified star excursion balance test. In the results, differences were found between the MR and MRD groups in PL and mGCM activities in the 1 section (p = 0.008, p = 0.036) and between the MD and MRD groups in mGCM activity in the 4 and 5 sections (p = 0.049, p = 0.004). We suggest that the application of MRD is the most effective intervention for increasing muscle activation of the PL and mGCM during the modified star excursion balance test.

Advances in study of surgical approaches and MRI evaluation of total hip arthroplasty

To review the research on different surgical approaches and MRI evaluation of total hip arthroplasty (THA), to clarify the possible muscle damage caused by different approaches, and to help clinicians avoid intraoperative muscle damage and identify the causes of certain muscle-related complications after operation. The research literature on different surgical approaches and MRI evaluation of THA at home and abroad was extensively reviewed to summarize the MRI performance of the posterior approach, modified direct lateral approach, direct anterior approach, and minimally invasive anterolateral approach (also called Orthopadische Chirurgie Munchen approach). The traditional posterior approach mainly damages the short external rotator muscle group and increases the incidence of postoperative dislocation; the piriformis-keeping posterior approach significantly improves the quality of the pyriformis tendon in the postoperative period, but it may lead to damage to the intrapelvic portion of the piriformis muscle. The modified direct lateral approach mainly damages the gluteus medius muscle, which increases the risk of postoperative claudication. The direct anterior approach mainly damages the vastus tensoris muscle and may result in damage to the short external rotator muscle group and the muscles around the incision. The minimally invasive anterolateral approach primarily damages the superior gluteal nerve, which subsequently leads to denervation of the broad fascial tensor fasciae latae, and this approach may also result in injury to the gluteus medius and gluteus minimus muscles. The muscle damage status significantly affects prognosis, and the minimally invasive approach is more suitable for elderly patients. MRI can clarify the different types of muscle damage caused by different surgical approaches. Minimally invasive approaches can reduce muscle damage and improve postoperative function compared with traditional approaches, and can benefit elderly patients more, but due to the small field, forcing to expand the surgical field will lead to unintended muscle damage and reduce postoperative function.

Low Inter-Rater Reliability and Reproducibility of Neck Reflex/“Adler-Langer” Points in Neural Therapy Diagnostics but Increased Pressure Pain Threshold after Therapy: Results of a Randomized Controlled Observer-Blind Trial

Background: Neck reflex points or Adler-Langer points are commonly used in neural therapy to detect so-called interference fields. Chronic irritations or inflammations in the sinuses, teeth, tonsils, or ears are supposed to induce tension and tenderness of the soft tissues and short muscles in the upper cervical spine. The individual treatment strategy is based on the results of diagnostic Adler-Langer point palpation. This study investigated the inter- and intra-rater reliability and explored treatment effects. Methods: We performed a randomized controlled trial with 104 inpatients (80.8% female, 51.8 ± 12.74 years) of a German department for internal and integrative medicine. Patients were randomized to individual neural therapy according to the pathological findings (n = 48) or no treatment (n = 56). In each patient, three experienced raters (20–45 years of experience in neural therapy) and two novice raters (medical students) rated Adler-Langer points rigidity on a standardized rating scale (“strong,” “weak,” “none”). The patients independently evaluated the tenderness on palpation of the eight points using the same scale. Pressure pain thresholds were assessed at the eight Adler-Langer points. All patients were retested after 30 min. The five raters were blinded to treatment allocation and assessments of the other raters. Video recordings were obtained to assess the consistency of the areas tested by the different raters. Results: Agreement between patients and raters (Cohen’s kappa = 0.161–0.400) and inter-rater reliability were low (Fleiss kappa = 0.132–0.150). Moreover, the individual agreement (pre-post comparisons in untreated patients) was similarly low even in experienced raters (Cohen’s kappa = 0.099–0.173). Video documentation suggests that raters do not place their fingers in the correct segments (percentage of correct position: 42.0–60.6%). Pressure pain thresholds at five of the eight Adler-Langer points showed significant changes after treatment compared to none in the control group. Conclusion: Under this artificial experimental setting, this method of Adler-Langer point palpation has not proven to be a reliable diagnostic tool. But it could be shown that, as claimed by the method, the tenderness in five of eight Adler-Langer points decreased after neural therapy.

Muscle-Tendon Unit Properties in Mice Bred for High Levels of Voluntary Running: Novel Physiologies, Coadaptation, Trade-Offs, and Multiple Solutions in the Evolution of Endurance Running.

AbstractMuscle-tendon unit (MTU) morphology and physiology are likely major determinants of locomotor performance and therefore Darwinian fitness. However, the relationships between underlying traits, performance, and fitness are complicated by phenomena such as coadaptation, multiple solutions, and trade-offs. Here, we leverage a long-running artificial selection experiment in which mice have been bred for high levels of voluntary running to explore MTU adaptation, as well as the role of coadaptation, multiple solutions, and trade-offs, in the evolution of endurance running. We compared the morphological and contractile properties of the triceps surae complex, a major locomotor MTU, in four replicate selected lines to those of the triceps surae complex in four replicate control lines. All selected lines have lighter and shorter muscles, longer tendons, and faster muscle twitch times than all control lines. Absolute and normalized maximum shortening velocities and contractile endurance vary across selected lines. Selected lines have similar or lower absolute velocities and higher endurance than control lines. However, normalized shortening velocities are both higher and lower in selected lines than in control lines. These findings potentially show an interesting coadaptation between muscle and tendon morphology and muscle physiology, highlight multiple solutions for increasing endurance running performance, demonstrate that a trade-off between muscle speed and endurance can arise in response to selection, and suggest that a novel physiology may sometimes allow this trade-off to be circumvented.

Lower Extremity Muscle Tendon Interaction Around Knee During Gait Among Adolescent Children with Cerebral Palsy with Varying Crouch Angle.

Optimal management and surgical planning of severe bony deformities and muscle tendon unit contractures demands comprehensive evaluation of all structures including the dynamic muscle tendon length of all muscles around the joint during gait. Present study aimed to explore dynamic muscle-tendon length for all muscles around the knee joint along with pelvis, hip, and ankle joint kinematics among adolescent children with varying crouch angle. Muscle-tendon length of 29 adolescent children with cerebral palsy with varying crouch angles was computed using a full-body musculo-skeletal model and expressed as a percentage of muscle-tendon length during walking compared to resting condition. Children with knee flexion angle greater than 25° demonstrated lower anterior pelvic tilt and 11% greater muscle-tendon length of semimembranosus and biceps femoris during stance phase of gait compared to children with knee flexion angle less than 25° and typically developing children (p < 0.01). The findings of present study reported that routine bedside clinical evaluation in adolescent children with knee flexion angle greater than 25° revealed moderate shortening of hamstring muscle in supine position. Whereas instrumented objective evaluation of gait demonstrated lengthened hamstring muscle and reduced hip extension and relatively lower anterior pelvic tilt. Therefore, it may be valuable to add objective assessment of dynamic muscle-tendon length to kinematics of all lower-extremity joint motion during gait, in order to understand the muscle-joint interactions; particularly in children with severe crouch and plan specific, tailor-made surgical and non-surgical interventions.

Resistance exercise following short term muscle disuse leads to enhanced mitochondrial activity and dynamics

Introduction: Short-term muscle unloading (~7-10 days) can be usually experienced following injury or hospitalisation, leading to muscle disuse atrophy, muscle weakness and changes in motor control. In such contexts, exercise countermeasures can be employed to overcome these neuromuscular impairments. Surprisingly, the effects of exercise countermeasures following the exposure to muscle unloading has been scarcely investigated. Hence, this study aimed to investigate the functional and molecular adaptations to a 21-day resistance training (RT) program following short term muscle disuse. We hypothesised that a period of resistance exercise following short-term unloading would speed up the recovery on muscle mass and function mostly by an effcient counteraction of the molecular regulators of muscle disuse atrophy consistent with the exercise modality employed. Methods: A 10-day unilateral lower limb suspension (ULLS) model was applied to eleven healthy young males (22.09 ± 2.91 y), followed by a 21-day RT program for the knee extensors performed at 70% of the 1RM (3 times/wk, 9 sessions in total). Data acquisition was performed before the ULLS period, after 10 days of unloading and after 21 days of resistance exercise. Quadriceps femoris isometric maximum voluntary contraction (MVC) was evaluated by dynamometry and quadriceps CSA was assessed by ultrasonography. Succinate dehydrogenase (SDH, a key component of the citric acid cycle and of the respiratory electron transfer chain) staining was performed on frozen cryosections obtained from VL biopsies, whereas western blot analyses were carried out for several mitochondrial-related proteins and transcriptomics data were obtained by RNA-seq. Results: Following ULLS, QF MVC and CSA decreased (-29.3%, p&lt;0.001, and -4.5%, p&lt;0.05, respectively). After the 21-d of RT, MVC was fully brought back (+42% compared to post-ULLS) whereas QF CSA showed a very marked hypertrophy (+18.6%, p&lt;0.001, compared to post-ULLS). SDH immunoreactivity was not affected by unloading but revealed a significant increase after exercise compared to post ULLS values (~+20%, p&lt;0.001). In addition, mitochondrial dynamics were highly influenced by resistance exercise, as mitochondrial pro-fusion (MFN1, MFN2, OPA1) and fission (DRP1, pDRP1616) proteins were markedly increased in response to RT compared to post-ULLS values (p&lt;0.05). Further, PGC-1a levels showed a trend to decrease after ULLS but even a stronger trend to increase after resistance exercise compared to post-ULLS (p=0.056). Transcriptomics analyses showed that the most differentially expressed genes were identified in the pathways related to oxidative phosphorylation, in which the top regulated genes after resistance training were mitochondrial related genes (CKMT2, UQCRH, ACSS1, MDH1, COX7A2, CYCS, SLC16A1), presenting a marked reduction after ULLS and being significantly enhanced after RT. When compared to baseline, the genes which showed a positive “rebound effect” after resistance exercise were mostly related to mitochondrial function (MT-ATP6, MT-CO2, MT-ND3). Noteworthy, among these latter genes, the top upregulated one was APLNR, coding for apelin receptor protein, a positive regulator of inter-myofibrillar mitochondrial content in sarcopenia and ageing. Conclusions: Resistance exercise was effective in recovering muscle mass and function after 10 days of disuse, but it enhanced mitochondrial activity, biogenesis, and dynamics far beyond the expected effects for such exercise modality. In fact, mitochondrial-related genes expression was the most affected by exercise. This suggests that mitochondrial dynamics could play an essential role in the recovery of neuromuscular alterations induced by short term disuse. We put forward the hypothesis that the prior level of physical activity and a prior exposure to short-term muscle disuse could be driving the nature of adaptations to subsequent resistance training. Funding: The present work was funded by the Italian Space Agency (ASI), MARS-PRE, Project, n. DC-VUM-2017-006. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

SERCA mediated thermogenesis during contraction-relaxation cycle in rat skeletal muscle in vivo

BACKGROUND: Across the lifespan, body temperature homeostasis is tightly regulated and impacts various physiological phenomena. In skeletal muscle, heat is produced via contraction-dependent (shivering) and independent (nonshivering) mechanisms, regulating the body temperature and muscle physiology including contractile properties. PURPOSE: In this study, we aimed to reveal the intracellular temperature dynamics in skeletal muscle in vivo during the contraction-relaxation cycle. Additionally, we tested the hypothesis that calcium ion (Ca2+) handling mediated by sarcoplasmic reticulum Ca2+ ATPase (SERCA) is involved in the thermogenesis process during contraction-relaxation cycle in skeletal muscle fibers. METHOD: The spinotrapezius muscle of anesthetized adult male Wistar rats (n = 18) was exteriorized and subjected to microinjection of fluorescent probe Cellular Thermoprobe for Fluorescence Ratio (49.3 μM) for intracellular temperature imaging in vivo. The fluorescence ratio (R: 580 nm / 515 nm) was measured in vivo during temperature increases induced by an external heater for thermoprobe calibration. R was also measured following Ca2+ injection (3.9 nL, 2.0 mM), and Ca2+ injection with SERCA inhibition by cyclopiazonic acid (CPA, 100 μM). RESULTS: The fluorescence ratio linearly increased with the increase of the muscle surface temperature from 25 °C to 40 °C (r2 = 0.97, P &lt; 0.01). The intracellular temperature in muscle was increased and sustained following the Ca2+ injection and this thermogenetic response was significantly suppressed with SERCA inhibition (Ca2+: 38.3 ± 1.4 °C vs Ca2++CPA: 28.3 ± 2.8 °C, P &lt; 0.01 at 1 min following injection). Importantly, elevated muscle temperature occurred predominantly in the muscle relaxation phase that followed the muscle shortening: That shortening occurred immediately and transiently after the Ca2+ injection. CONCLUSION: In this investigation, we demonstrated a novel technique for in vivo intracellular temperature imaging of skeletal muscle. Herein we demonstrate that substantial heat is generated concomitantly with SERCA mediated Ca2+ handling and muscle relaxation. This work was supported by JSPS KAKENHI Grant Numbers 20H04074, 19K22800. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effective Stretching Positions of the Piriformis Muscle Evaluated Using Shear Wave Elastography.

Piriformis syndrome is often associated with muscle spasms and shortening of the piriformis muscle (PM). Physical therapy, including static stretching of the PM, is one of the treatments for this syndrome. However, the effective stretching position of the PM is unclear in vivo. This study aimed to determine the effective stretching positions of the PM using ultrasonic shear wave elastography. Observational study. Twenty-one healthy young men (22.7 [2.4]y) participated in this study. The shear elastic modulus of the PM was measured at 12 stretching positions using shear wave elastography. Three of the 12 positions were tested with maximum internal rotation at 0°, 20°, or 40° hip adduction in 90° hip flexion. Nine of the 12 positions were tested with maximum external rotation at positions combined with 3 hip-flexion angles (70°, 90°, and 110°) and 3 hip-adduction angles (0°, 20°, and 40°). The shear elastic modulus of the PM was significantly higher in the order of 40°, 20°, and 0° of adduction and higher in external rotation than in internal rotation. The shear elastic modulus of the PM was significantly greater in combined 110° hip flexion and 40° adduction with maximum external rotation than in all other positions. This study revealed that the position in which the PM was most stretched was maximum external rotation with 110° hip flexion and 40° hip adduction.

Muscle Activity and Kinematics During Three Hamstring Strengthening Exercises Compared to Sprinting: A Cross-Sectional Study.

During sprinting, the biceps femoris long head predominantly gets injured, while hamstring strengthening exercises predominantly activate the semitendinosus more effectively. Understanding how joint dominance influences hamstring activity may offer clarity on appropriate exercise selection in strengthening programs. This study compared three hip-dominant hamstring exercises: the rocker, perpetuum mobile fast and slow (PMfast and PMslow) and the Nordic Hamstring exercise (NHE) on their potential to simulate sprint-like activity and kinematics. Muscle activity of the posterior kinetic chain (biceps femoris, semitendinosus, gluteus maximus, and medial gastrocnemius) was measured with surface electromyography (sEMG) during the exercises and treadmill running at 75% of the individual maximal sprint velocity in male athletes. sEMG data were normalized to maximal sprinting. 3D-motion capture was employed to assess hip and knee angles. Eight male athletes were included (age: 24.0 years ± SD 2.9; body mass: 76.8 kg ± 7.7; height: 1.79 m ± 0.08). Greater activity of the hamstrings occurred during the explosive exercises ranging from 63.9% [95%CI: 56.3-71.5%] (rocker) to 49.0% [95%CI: 40.4-57.6%] (PMfast) vs.34.0% [95%CI: 29.1-38.9%] (NHE) to 32.1% [95%CI: 26.9-37.3%] (PMslow). The rocker showed greatest hamstring and gluteus maximus activity. Biceps femoris consistently showed greater activity than the semitendinosus across all exercises in peak (mean difference: 0.16, [95%CI: 0.07-0.26]) and average (mean difference: 0.06, [95%CI: 0.01-0.11]) activity. PMfast, PMslow and NHE demonstrated less hip flexion angle at peak hamstring activity than the rocker and high-speed running and every exercise showed less hamstring elongation stress than during high-speed running. Hamstring activity is comparable to high-intensity treadmill running for NHE and PMslow, and greater for the rocker and PMfast. Gluteus maximus activity varied, with the rocker and PMfast showing greater activity than in sprinting. All examined exercises demonstrated their peak activity at short hamstring muscle length. 3b.

Unusual cause of muscle weakness, type II respiratory failure and pulmonary hypertension: a case report of ryanodine receptor type 1(RYR1)-related myopathy

BackgroundPatients with congenital myopathies may experience respiratory involvement, resulting in restrictive ventilatory dysfunction and respiratory failure. Pulmonary hypertension (PH) associated with this condition has never been reported in congenital ryanodine receptor type 1(RYR1)-related myopathy.Case presentation A 47-year-old woman was admitted with progressively exacerbated chest tightness and difficulty in neck flexion. She was born prematurely at week 28. Her bilateral lower extremities were edematous and muscle strength was grade IV−. Arterial blood gas analysis revealed hypoventilation syndrome and type II respiratory failure, while lung function test showed restrictive ventilation dysfunction, which were both worse in the supine position. PH was confirmed by right heart catheterization (RHC), without evidence of left heart disease, congenital heart disease, or pulmonary artery obstruction. Polysomnography indicated nocturnal hypoventilation. The ultrasound revealed reduced mobility of bilateral diaphragm. The level of creatine kinase was mildly elevated. Magnetic resonance imaging showed myositis of bilateral thigh muscle. Muscle biopsy of the left biceps brachii suggested muscle malnutrition and congenital muscle disease. Gene testing revealed a missense mutation in the RYR1 gene (exon33 c.C4816T). Finally, she was diagnosed with RYR1-related myopathy and received long-term non-invasive ventilation (NIV) treatment. Her symptoms and cardiopulmonary function have been greatly improved after 10 months.ConclusionsWe report a case of RYR1-related myopathy exhibiting hypoventilation syndrome, type II respiratory failure and PH associated with restrictive ventilator dysfunction. Pulmonologists should keep congenital myopathies in mind in the differential diagnosis of type II respiratory failure, especially in patients with short stature and muscle weakness.

Muscle Tone, Stiffness, and Elasticity in Elite Female Cyclists after Consecutive Short Competitions.

For professional road cyclists, most overload injuries affect the lower limbs. They are mostly represented by contractures or muscle shortening, characterised by a variation of muscular tone, stiffness, and elasticity. This real-life study aimed to assess specific mechanical parameters in top-class female cyclists who participated in 3 races a week. Hypothesis. Muscle tone, stiffness, and elasticity will be affected immediately after competition and at the end of the week due to accumulated fatigue. Six professional cyclists were evaluated. This pilot study consisted of a controlled trial and three days of competition, with rest days between them. MyotonPRO was used to measure tone, stiffness, and elasticity in six leg muscles: vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), lateral gastrocnemius (LG), and medial gastrocnemius (MG). Daily basal and pre- and postrace measures were carried through to the 3 races in a week. The muscular tone of VL, VM, LG, and MG and the stiffness of VL, VM, RF, BF, LG, and MG decreased after races. VL and RF were mostly affected by (p=0.05) and (p=0.009), respectively. Basal elasticity improved over time until the last day. Muscle tone and stiffness decreased after a very intense and exhausting cycling endurance competition. Basal elasticity improved immediately after the race and continued this trend until the end of the week. More research is needed on changes in mechanical properties in competition and risk prevention of injuries.

Effects of Neuromuscular Electrical Stimulation and Therapeutic Ultrasound on Quadriceps Contracture of Immobilized Rats.

Quadriceps contracture is a condition where the muscle-tendon unit is abnormally shortened. The treatment prognosis is guarded to poor depending on the progress of the disease. To improve the prognosis, we investigated the effectiveness of therapeutic ultrasound and NMES in treating quadriceps contracture in an immobilized rat model. Thirty-six Wistar rats were randomized into control, immobilization alone, immobilization and spontaneous recovery, immobilization and therapeutic ultrasound, immobilization and NMES, and immobilization and therapeutic ultrasound and NMES combination groups. The continuous therapeutic ultrasound (frequency, 3 MHz, intensity 1 W/cm2) and NMES (TENS mode, frequency 50 Hz; intensity 5.0 ± 0.8 mA) were performed on the quadriceps muscle. On Day 15, immobilization-induced quadriceps contracture resulted in a decreased ROM of the stifle joint, reduction in the sarcomere length, muscle atrophy, and muscle fibrosis. On Day 43, therapeutic ultrasound, NMES, and combining both methods improved muscle atrophy and shortening and decreased collagen type I and III and α-SMA protein. The combination of therapeutic ultrasound and NMES significantly reduced the mRNA expression of IL-1β, TGF-β1, and HIF-1α and increased TGF-β3. Therefore, the combination of therapeutic ultrasound and NMES is the most potent rehabilitation program for treating quadriceps contracture.

Intrinsic ankle stiffness is associated with paradoxical calf muscle movement but not postural sway or age.

Due to Achilles tendon compliance, passive ankle stiffness is insufficient to stabilise the body when standing. This results in 'paradoxical' muscle movement, whereby calf muscles tend to shorten during forward body sway. Natural variation in stiffness may affect this movement. This may have consequences for postural control, with compliant ankles placing greater reliance upon active neural control rather than stretch reflexes. Previous research also suggests ageing reduces ankle stiffness, possibly contributing to reduced postural stability. Here we determine the relationship between ankle stiffness and calf muscle movement during standing, and whether this is associated with postural stability or age. Passive ankle stiffness was measured during quiet stance in 40 healthy volunteers ranging from 18 to 88years of age. Medial gastrocnemius muscle length was also recorded using ultrasound. We found a significant inverse relationship between ankle stiffness and paradoxical muscle movement, that is, more compliant ankles were associated with greater muscle shortening during forward sway (r≥0.33). This was seen during both quiet stance as well as voluntary sway. However, we found no significant effects of age upon stiffness, paradoxical motion or postural sway. Furthermore, neither paradoxical muscle motion nor ankle stiffness was associated with postural sway. These results show that natural variation in ankle stiffness alters the extent of paradoxical calf muscle movement during stance. However, the absence of a clear relationship to postural sway suggests that neural control mechanisms are more than capable of compensating for a lack of inherent joint stiffness.

The role of surface electromyography in confirming the effect of blepharoplasty on strength of levator palpebrae superioris muscle in congenital blepharoptosis

BackgroundBlepharoptosis is an abnormal drooping of the upper eyelid margin with the eye in the primary gaze position. The clinical evaluating tests of upper eyelid muscle function lack objectivity, while surface electromyography (SEMG) is an objective evaluating tool of muscle power. We aimed to confirm the effect of blepharoplasty on levator muscle power after its shortening via levator aponeurosis resection surgery in cases of congenital ptosis through electrophysiological and clinical studies.The study included 40 patients aged ≥ 10 years with congenital blepharoptosis from the ophthalmology department of our university hospital, along with 40 age- and sex-matched healthy controls. All participants were subjected to clinical and electrophysiological assessment of levator muscle before and after blepharoplasty.ResultsThere was a significant improvement in clinical and electrophysiological findings among cases post-surgery compared with preoperative parameters. We recorded clinical improvement in 90% of patients postoperatively regarding eyelid morphology, symmetry, and visual field. Meanwhile, 82.5% of patients showed improvement in their muscle power using SEMG parameters in terms of improved muscle amplitude and firing characters compared with preoperative measures.ConclusionSEMG provides a standardized, objective method of analysis of upper eyelid muscle power. It confirms that levator muscle shortening via levator aponeurosis resection surgery could increase its power based on its pre-surgical power and electrophysiological characteristics; so, it could be considered an indicator of post-operative improvement of ptosis based on electrophysiological measurements before surgery. The relatively short follow-up period and lack of quantitative analysis of EMG were limitations of this study.

The morphometric parameters of the biceps brachii: cadaveric study.

The biceps brachii (BB) is a fusiform muscle comprising of two muscular bellies located in the anterior compartment of the arm. Its primary function includes elbow flexion and forearm supination. The study aimed to examine the morphometric parameters of the BB in adult cadaveric specimens. This dissection-based study examined the anatomy of the BB in 40 arms taken from 20 Thiel embalmed European cadavers, including 13 males with an average age of 81 years and seven females with an average age of 84 years. The investigation included an observational inspection of the BB morphology and collected 19 parameters, comprising the lengths and widths of the short and long head tendons and muscle bellies. The observation analysis showed that the anatomy of the BB consisted mainly of two muscle bellies: a short head and a long head. An additional third humeral head, originating from the anteromedial aspect of the mid of the humerus and inserted into the common biceps tendon, was observed in four (10%) specimens. The average lengths of the short head and long head were 35.98 ± 3.44cm and 38.90 ± 3.40cm, respectively. There was no difference in the BB parameters according to the arm sides. However, the male specimens showed greater BB parameters than the female specimens. The short head had a greater muscle belly, while the long head had a longer origin and insertion tendons. The BB parameters were correlated positively with the humerus length.

Relationship between pectoralis major stiffness and shoulder extension range of motion.

This study aimed to investigate the correlation between the passive muscle stiffness of the pectoralis major muscle pars clavicularis (PMc) and shoulder extension range of motion (ROM) in both male and female participants. Thirty-nine (23 male/16 female) physically active and healthy participants volunteered in this study. After a standardized warm-up, the PMc stiffness was tested via shear wave elastography at a slightly stretched position (long muscle length) and in a non-stretched position (short muscle length). Additionally, a custom-made device and 3D motion capture assessed the active shoulder extension ROM. We found a significant moderate and negative relationship between shoulder extension ROM and PMc stiffness at long muscle length (rs = -0.33; p = 0.04) but not at short muscle length (r = -0.23; p = 0.17). Additionally, there was no significant difference between male and female participants in the correlation analyses at both elbow angles. The moderate correlation between PMc stiffness at a slightly stretched position and shoulder extension ROM suggests that additionally, other structures such as nerves/fascia stiffness or even stretch tolerance might be factors that can be related to shoulder extension ROM.

Serious Game with Electromyography Feedback and Physical Therapy in Young Children with Unilateral Spastic Cerebral Palsy and Equinus Gait: A Prospective Open-Label Study.

The clinical effects of a serious game with electromyography feedback (EMGs_SG) and physical therapy (PT) was investigated prospectively in children with unilateral spastic cerebral palsy (USCP). An additional aim was to better understand the influence of muscle shortening on function. Thirty children with USCP (age 7.6 ± 2.1 years) received four weeks of EMGs_SG sessions 2×/week including repetitive, active alternating training of dorsi- and plantar flexors in a seated position. In addition, each child received usual PT treatment ≤ 2×/week, involving plantar flexor stretching and command strengthening on dorsi- and plantar flexors. Five-Step Assessment parameters, including preferred gait velocity (normalized by height); plantar flexor extensibility (XV1); angle of catch (XV3); maximal active ankle dorsiflexion (XA); and derived coefficients of shortening, spasticity, and weakness for both soleus and gastrosoleus complex (GSC) were compared pre and post treatment (t-tests). Correlations were explored between the various coefficients and gait velocities at baseline. After four weeks of EMGs_SG + PT, there was an increase in normalized gait velocity from 0.72 ± 0.13 to 0.77 ± 0.13 m/s (p = 0.025, d = 0.43), a decrease in coefficients of shortening (soleus, 0.10 ± 0.07 pre vs. 0.07 ± 0.08 post, p = 0.004, d = 0.57; GSC 0.16 ± 0.08 vs. 0.13 ± 0.08, p = 0.003, d = 0.58), spasticity (soleus 0.14 ± 0.06 vs. 0.12 ± 0.07, p = 0.02, d = 0.46), and weakness (soleus 0.14 ± 0.07 vs. 0.11 ± 0.07, p = 0.005, d = 0.55). At baseline, normalized gait velocity correlated with the coefficient of GSC shortening (R = -0.43, p = 0.02). Four weeks of EMGs_SG and PT were associated with improved gait velocity and decreased plantar flexor shortening. A randomized controlled trial comparing EMGs_SG and conventional PT is needed.

Clinical Outcomes of Bipolar Hemiarthroplasty with a Conjoined Tendon-Preserving Posterior Approach for Femoral Neck Fractures.

Background and Objectives: The conventional posterior approach in the lateral decubitus position is widely used for femoral neck fractures in femoral hemiarthroplasty. Postoperative dislocation is the major problem with this approach. The conjoined tendon-preserving posterior (CPP) approach is a less invasive surgical approach than the conventional posterior approach to the hip, maintains posterior stability, and preserves short external rotators and joint capsules. However, the mention was required to avoid muscle damage and whether muscle damage affects postoperative dislocation or not. The current study aimed to evaluate the clinical results of the CPP approach in hemiarthroplasty for femoral neck fractures and identify muscle damage risk factors. Materials and Methods: This study was a retrospective cohort study and included 170 hips in 168 patients. The mean age at the operation was 81.2 years. The preservation rate of the internal obturator muscle and gemellus inferior muscle and factors related to intraoperative short rotator muscle injury were investigated retrospectively. The postoperative complications and the relation between muscle damage and postoperative dislocation were investigated. Results: In the four hips (2.3%) with the obturator internus muscle damage, thirty-eight hips (22.4%) with gemellus inferior muscle damage were detected; in the muscle-damaged cases, the high body mass index (BMI) was significantly higher. The complication occurred in four hips (2.3%), including postoperative posterior dislocation in one hip without muscle damage (0.6%). Postoperative infection occurred in one hip (0.6%), and peroneal or sciatic nerve paralysis was suspected in two hips (1.1%). Conclusions: Compared to the conventional posterior approach in previous reports, the CPP approach reduces postoperative dislocation. A higher BMI is a risk factor for muscle damage, and the gemellus inferior muscle damage has no effect on postoperative dislocation. The CPP approach for BHA appeared to be an effective treatment method.

Residual force depression is not related to positive muscle fascicle work during submaximal voluntary dorsiflexion contractions in humans.

Residual force depression (rFD) following active muscle shortening is assumed to correlate most strongly with muscle work, but this has not been tested during voluntary contractions in humans. Using dynamometry, we compared steady-state ankle joint torques (N=16) following tibialis anterior (TA) muscle-tendon unit (MTU) lengthening and shortening to the time-matched torque during submaximal voluntary fixed-end dorsiflexion reference contractions (REF) at a matched MTU length and EMG amplitude. Ultrasound revealed significantly reduced (P<0.001) TA fascicle shortening amplitudes during MTU lengthening without a preload over small and medium amplitudes, respectively, relative to REF. MTU lengthening with a preload over a large amplitude significantly (P<0.001) increased fascicle shortening relative to REF, as well as stretch amplitudes relative to MTU lengthening without a preload (P=0.001). Significant (P=0.028) steady-state fascicle force enhancement relative to REF was observed following MTU lengthening, and was similar among MTU lengthening-hold conditions (3-5%). MTU shortening with and without a preload over small and large amplitudes significantly (P<0.001) increased positive fascicle and MTU work relative to REF, but significant (P=0.006) rFD was observed following MTU shortening with a preload (7-10%) only. rFD was linearly related to positive MTU work [rrm (47)=0.48, P<0.001], but not positive fascicle work [rrm (47)=0.16, P=0.277]. Our findings indicate that MTU lengthening without substantial fascicle stretch enhances steady-state force output, which might arise from less shortening-induced rFD. Our findings also indicate similar rFD following different amounts of positive fascicle/MTU work, which cautions against using work to predict rFD during submaximal voluntary contractions. KEY POINTS: Accurately predicting muscle force is challenging because active muscle shortening depresses force output. The residual force depression (rFD) that exists following active muscle shortening is commonly assumed to correlate strongly and positively with muscle work. We found that tibialis anterior muscle fascicle work and muscle-tendon unit work did not accurately predict rFD during submaximal voluntary dorsiflexion contractions. Fascicle shortening during fixed-end reference contractions also potentially induced rFD of 3-5%, which was similar to the rFD following muscle-tendon unit shortening without a preload. A higher number of active muscle fibres during shortening probably increased rFD, which suggests that motor unit recruitment during shortening might predict rFD.