Changes In Muscle Architecture Research Articles

Intramuscular adipose tissue, muscle area, and power as predictors of performance in breast cancer survivors.

The decline in physical performance, assessed by physical tests such as the timed up and go (TUG) test, is a consequence of reduced physiological reserves at higher levels of a hierarchical process. This occurs due to changes in muscle architecture, including atrophy and fat infiltration into the muscles, which in turn lead to changes in muscle function, resulting in reduced muscle strength and power and, consequently, affecting physical performance. This study investigated predictive factors for physical performance in breast cancer survivor (BCS), focusing on intramuscular adipose tissue (IMAT), quadríceps muscle area (QMA), and muscular power. This observational, analytical, and cross-sectional study included 23 women without a history of cancer (age, 58.5 ± 8.3years; BMI, 27.2 ± 5.1kg/m2) and 56 BCS (age, 58.5 ± 8.3years; BMI, 27.2 ± 5.1kg/m2). QMA and IMAT were assessed using computed tomography images. Muscular power and physical performance were measured using the 5-repetition sit-to-stand and TUG tests, respectively. IMAT (r = 0.4, P < 0.01) and muscular power (r = - 0.4, P < 0.01) were associated with TUG performance in BCS, whereas QMA (r = - 0.22, P = 0.10) showed no significant association. QMA (r = 0.55, P < 0.01) was associated with muscular power, while no significant association was found between IMAT and muscular power (r = - 0.05, P = 0.73). Age explained 19% (P < 0.01) of TUG performance variability. Adding muscular power increased explanatory power by 12% (P < 0.01), and including IMAT further increased it by 7% (P = 0.02) for TUG performance. Collectively, age, muscular power, and IMAT accounted for 38% of the performance variance in the TUG test (age, B = 0.06, P = 0.043; muscular power, B = - 0.01, P = 0.002; IMAT, B = - 0.05, P = 0.020). Our findings suggest that IMAT and muscular power predict the physical performance of BCS, while QMA does not have the same predictive capability.

Determining Changes in Muscle Size and Architecture After Exercise Training: One Site Does Not Fit all.

Nunes, JP, Blazevich, AJ, Schoenfeld, BJ, Kassiano, W, Costa, BDV, Ribeiro, AS, Nakamura, M, Nosaka, K, and Cyrino, ES. Determining changes in muscle size and architecture after exercise training: One site does not fit all. J Strength Cond Res 38(4): 787-790, 2024-Different methods can be used to assess muscle hypertrophy, but the effects of training on regional changes in muscle size can be detected only using direct muscle measurements such as muscle thickness, cross-sectional area, or volume. Importantly, muscle size increases vary across regions within and between muscles after resistance training programs (i.e., heterogeneous, or nonuniform, muscle hypertrophy). Muscle architectural changes, including fascicle length and pennation angle, after resistance and stretch training programs are also region-specific. In this paper, we show that the literature indicates that a single-site measure of muscle shape does not properly capture the effects achieved after exercise training interventions and that conclusions concerning the magnitude of muscle adaptations can vary substantially depending on the muscle site to be examined. Thus, we propose that measurements of muscle size and architecture should be completed at multiple sites across regions between the agonist muscles within a muscle group and along the length of the muscles to provide an adequate picture of training effects.

Efficacy of accommodating variable-resistance training on muscle architecture, peak torque, and functional performance in patients with juvenile idiopathic arthritis: A randomized controlled trial

PurposeThis study sought to find out if a 6-week accommodating variable-resistance (AcVR) training might enhance muscle architecture, peak torque, and functional performance in patients with juvenile idiopathic arthritis (Juv-IA). MethodsFifty-eight patients with polyarticular Juv-IA (aged 12–18 years) were involved in a randomized controlled trial. They were allocated into two groups: the AcVR group (n = 29; underwent AcVR training, and the control group (n = 29; received the usual exercise regimen). Interventions were applied three times a week over six consecutive weeks. Measurements were done at baseline and after the intervention. The primary outcome measures were muscle architecture and peak torque, with functional capacity being the secondary measure. ResultsCompared to the control group, the AcVR group showed favorable pre-to-post changes in muscle architecture [fascicle length (P = 0.0007, η2p = .18), pennation angle (P = 0.0004, η2p = .20), and muscle thickness (P = 0.001, η2p = .17)]. Further, the AcVR group revealed a greater increase in peak concentric torque of knee extensors at angular speeds of 120°/sec [right side (P = 0.0032, η2p = .08); left side (P = 0.039, η2p = .07)] and 180°/sec [right side (P = 0.01, η2p = .11); left side (P = 0.014, η2p = .10)]. Furthermore, The AcVR group achieved more conducive changes in functional performance [6-min walk test (P = 0.003, η2p = .15), timed up and down stair test (P = 0.009, η2p = .12), and 4 × 10 m shuttle run test (P = 0.036, η2p = .08)]. ConclusionA 6-week AcVR training is potentially effective for improving muscle architectural qualities, enhancing peak muscle torque, and boosting functional performance in patients with Juv-IA without experiencing any detrimental side effects.

Impact of Reverse Shoulder Arthroplasty Design and Patient Shoulder Size on Moment Arms and Muscle Fiber Lengths in Shoulder Abductors.

Reverse shoulder arthroplasty (RSA) increases the moment arm of the deltoid, however there is limited knowledge on the accompanying changes in muscle architecture that play a role in muscle force production. The purpose of our study is to use a geometric shoulder model to evaluate the anterior deltoid, middle deltoid, and supraspinatus regarding 1) differences in moment arms and muscle-tendon lengths in small, medium, and large native shoulders, and 2) impact of three RSA designs on moment arms, muscle fiber lengths, and force-length (F-L) curves. A geometric model of a native glenohumeral joint was developed, validated, and adjusted to represent small, medium, and large shoulders. Moment arms, muscle-tendon lengths, and normalized muscle fiber lengths were assessed for the supraspinatus, anterior deltoid, and middle deltoid from 0 to 90 degrees abduction. RSA designs were modeled and virtually implanted, including a lateralized glenosphere with an inlay-135-degree humeral component (LGMH), a medialized glenosphere with an onlay-145-degree humeral component (MGLH), and a medialized glenosphere with an inlay-155-degree humeral component (MGMH). Descriptive statistics were used to compare moment arms and normalized muscle fiber lengths. As shoulder size increased, moment arms and muscle-tendon lengths for the anterior deltoid, middle deltoid, and supraspinatus increased. All RSA designs achieved greater moment arms for the anterior and middle deltoid, with MGLH achieving the largest increase. The resting normalized muscle fiber length of the anterior and middle deltoid was substantially increased in the MGLH (1.29) and MGMH (1.24), shifting the operating ranges of these muscles to the descending portions of their F-L curves, while LGMH maintained a resting deltoid fiber length (1.14) and operating range similar to the native shoulder. All RSA designs demonstrated a decrease in native supraspinatus moment arm in early abduction, with the largest decrease in MGLH (-59%) and minimal decrease in LGMH (-14%). The supraspinatus operated on the ascending limb of its F-L curve in the native shoulder and remained on this portion of the F-L curve for all RSAs. Although MGLH maximizes abduction moment arm for the anterior and middle deltoid, overlengthening of the muscle may compromise deltoid muscle force production by forcing the muscle to operate on the descending portion of its F-L curve. In contrast, the LGMH design increases the abduction moment arm for the anterior and middle deltoid more modestly, while allowing the muscle to operate near the plateau of its F-L curve and maximizing its force producing potential.

Effect of 3 Weeks of Strict Head‑Down Tilt Bed Rest on Human Muscle Fuction and Architecture

The aim of this study was to first, experimentally measure in vivo changes in the length, fiber angle and thickness of the medial gastrocnemius muscle (MG) in young men in response to changes in foot position and joint moment during isometric plantar flexion and, in secondly, to compare the changes in the above characteristics of the muscular architecture that occur during the transition from a state of rest to a given isometric intensity during plantar flexion. The internal architecture of the MG was determined after 21-day of strict head‑down tilt bed rest (HDT). MG scanning was performed using ultrasound at rest at ankle joint angles of –15° (dorsiflexion), 0° (neutral), +15° and +30° (plantar flexion). Additional ultrasounds were performed during maximal voluntary contraction (MVC) and additionally at 80, 60, 40, and 20% of the MVC with the ankle in neutral position. In each position, longitudinal ultrasound images of the MG were obtained in a relaxed (passive) state with the determination of the length (Lf) and angles of fascicles (Θf) relative to the aponeurosis. After HDT, the thickness of the MG during graduated isometric force up to 80% of the MVC in the neutral position of the ankle joint remained constant. Various Lf and Θf and their changes after HDT can be a limiting factor in the generation of muscle contractile functions. The results of the study show that the change in muscle structure during contraction compared to rest, as measured by changes in muscle architecture, can be used to assess muscle mechanical output.

Pathophysiological interactions between sarcopenia and type 2 diabetes: A two-way street influencing diagnosis and therapeutic options.

This review will try to elucidate the interconnected pathophysiology of sarcopenia and type 2 diabetes (T2D) and will try to identify a common pathway to explain their development. To this end, the PubMed and Scopus databases were searched for articles published about the underlying pathophysiology, diagnosis and treatment of both sarcopenia and T2D. The medical subject heading (MeSH) terms 'sarcopenia' AND 'diabetes mellitus' AND ('physiopathology' OR 'diagnosis' OR 'therapeutics' OR 'aetiology' OR 'causality') were used. After screening, 32 papers were included. It was evident that sarcopenia and T2D share multiple pathophysiological mechanisms. Common changes in muscle architecture consist of a shift in myocyte composition, increased myosteatosis and a decreased capacity for muscle regeneration. Further, both diseases are linked to an imbalance in myokine and sex hormone production. Chronic low-grade inflammation and increased levels of oxidative stress are also known pathophysiological contributors. In the future, research efforts should be directed towards discovering common checkpoints in the development of T2D and sarcopenia as possible shared therapeutic targets for both diseases. Current treatment for T2D with biguanides, incretins and insulin may already convey a protective effect on the development of sarcopenia. Furthermore, attention should be given to early diagnosis of sarcopenia within the population of people with T2D, given the sizeable physical and medical burden it encompasses. A combination of simple diagnostic techniques could be used at regular diabetes check-ups to identify sarcopenia at an early stage and start lifestyle modifications and treatment as soon as possible.

Dense reconstruction of elephant trunk musculature

The elephant trunk operates as a muscular hydrostat1,2 and is actuated by the most complex musculature known in animals.3,4 Because the number of trunk muscles is unclear,5 we performed dense reconstructions of trunk muscle fascicles, elementary muscle units, from microCT scans of an Asian baby elephant trunk. Muscle architecture changes markedly across the trunk. Trunk tip and finger consist of about 8,000 extraordinarily filigree fascicles. The dexterous finger consists exclusively of microscopic radial fascicles pointing to a role of muscle miniaturization in elephant dexterity. Radial fascicles also predominate (at 82% volume) the remainder of the trunk tip, and we wonder if radial muscle fascicles are of particular significance for fine motor control of the dexterous trunk tip. By volume, trunk-shaft muscles6 comprise one-third of the numerous, small radial muscle fascicles; two-thirds of the three subtypes of large longitudinal fascicles (dorsal longitudinals, ventral outer obliques, and ventral inner obliques);7,8,9 and a small fraction of transversal fascicles. Shaft musculature is laterally, but not radially, symmetric. A predominance of dorsal over ventral radial muscles and of ventral over dorsal longitudinal muscles may result in a larger ability of the shaft to extend dorsally than ventrally10 and to bend inward rather than outward. There are around 90,000 trunk muscle fascicles. While primate hand control is based on fine control of contraction by the convergence of many motor neurons on a small set of relatively large muscles, evolution of elephant grasping has led to thousands of microscopic fascicles, which probably outnumber facial motor neurons.

Chronic changes in muscle architecture and aponeurosis structure following calf muscle strain injuries.

Muscle strain injuries in the human calf muscles are frequent sports injuries with high recurrence. Potential structural and functional changes in the medial head of the musculus gastrocnemius (GM) and the associated aponeurosis are not well documented. To test whether a GM muscle strain injury affects muscle fascicle length, pennation angle, and the morphology of the deep aponeurosis at rest and during muscle contraction long time after the injury. Additionally, electromyography (EMG) of the GM and the soleus muscle during a unilateral heel rise was measured in the injured and uninjured calf. GM fascicle length, pennation angle, and aponeurosis thickness was analyzed on dynamic ultrasonography (US) recordings in 10 participants with a chronic calf strain. In addition, US images taken across the distal portion and mid-belly of the GM were analyzed at three different ankle positions. EMG recordings were obtained during a unilateral heel rise. The pennation angle of the injured distal GM was significantly larger compared to the uninjured GM in the contracted, but not the relaxed state. Pennation angle increased more in the injured compared to the uninjured GM during contraction. Fascicle length was shorter in the most distal portion of the injured GM. Fascicles at the distal portion of the injured GM showed a pronounced curvilinear shape as the muscle contracted and the aponeurosis was enlarged in the injured compared to the uninjured GM. The ratio between GM and soleus EMG activity showed a significantly higher relative soleus activity in the injured compared to the healthy calf. The greater change in pennation angle and curvilinear fascicle shape during contraction suggest that a long-term consequence after a muscle strain injury is that some muscle fibers at the distal GM are not actively engaged. The significantly enlarged aponeurosis indicates a substantial and long-lasting connective tissue involvement following strain injuries.

The importance of serial sarcomere addition for muscle function and the impact of aging.

During natural aging, skeletal muscle experiences impairments in mechanical performance due, in part, to changes in muscle architecture and size, notably with a loss of muscle cross-sectional area. Another important factor that has received less attention is the shortening of fascicle length, potentially reflective of a decrease in serial sarcomere number (SSN). Interventions that promote the growth of new serial sarcomeres, such as chronic stretching and eccentric-biased resistance training, have been suggested as potential ways to mitigate age-related impairments in muscle function. While current research suggests it is possible to stimulate serial sarcomerogenesis in muscle in old age, the magnitude of sarcomerogenesis may be less than in young muscle. This blunted effect may be partly due to age-related impairments in the pathways regulating mechanotransduction, muscle gene expression, and protein synthesis, as some have been implicated in SSN adaptation. The purpose of this review was to investigate the impact of aging on the ability for serial sarcomerogenesis, and elucidate the molecular pathways that may limit serial sarcomerogenesis in old age. Age-related changes in mTOR, IGF-1, myostatin, and serum response factor signalling, MuRFs, and satellite cells may hinder serial sarcomerogenesis. In addition, our current understanding of SSN in older humans is limited by assumptions based on ultrasound-derived fascicle length. Future research should explore the effects of age-related changes in the identified pathways on the ability to stimulate serial sarcomerogenesis, and better estimate SSN adaptations to gain a deeper understanding of the adaptability of muscle in old age.

Influence of internal muscle properties on muscle shape change and gearing in the human gastrocnemii.

Skeletal muscles bulge when they contract. These three-dimensional shape changes, coupled with fiber rotation, influence a muscle's mechanical performance by uncoupling fiber velocity from muscle belly velocity (i.e., gearing). Muscle shape change and gearing are likely mediated by the interaction between internal muscle properties and contractile forces. Muscles with greater stiffness and intermuscular fat, due to aging or disuse, may limit a muscle's ability to bulge in width, subsequently causing higher gearing. The aim of this study was to determine the influence of internal muscle properties on shape change, fiber rotation, and gearing in the medial (MG) and lateral gastrocnemii (LG) during isometric plantar flexion contractions. Multimodal imaging techniques were used to measure muscle shear modulus, intramuscular fat, and fat-corrected physiological cross-sectional area (PCSA) at rest, as well as synchronous muscle architecture changes during submaximal and maximal contractions in the MG and LG of 20 young (24 ± 3 yr) and 13 older (70 ± 4 yr) participants. Fat-corrected PCSA was positively associated with fiber rotation, gearing, and changes in thickness during submaximal contractions, but it was negatively associated with changes in thickness at maximal contractions. Muscle stiffness and intramuscular fat were related to muscle bulging and reduced fiber rotation, respectively, but only at high forces. Furthermore, the MG and LG had varied internal muscle properties, which may relate to the differing shape changes, fiber rotations, and gearing behaviors observed at each contraction level. These results indicate that internal muscle properties may play an important role in mediating in vivo muscle shape change and gearing, especially during high-force contractions.NEW & NOTEWORTHY Here, we measured internal muscle properties in vivo to determine their influence on the varying shape change and gearing behaviors in the synergistic gastrocnemii muscles. These relationships have previously only been hypothesized or examined within isolated muscles during supramaximal contractions. Our results contribute to a more comprehensive understanding of the factors that influence a muscle's mechanical response to force with implications for preventing or treating muscle deficits associated with aging, disease, and disuse.

Age-related changes in human skeletal muscle microstructure and architecture assessed by diffusion-tensor magnetic resonance imaging and their association with muscle strength.

Diffusion-tensor magnetic resonance imaging (DT-MRI) offers objective measures of muscle characteristics, providing insights into age-related changes. We used DT-MRI to probe skeletal muscle microstructure and architecture in a large healthy-aging cohort, with the aim of characterizing age-related differences and comparing these to muscle strength. We recruited 94 participants (43 female; median age = 56, range = 22-89 years) and measured microstructure parameters-fractional anisotropy (FA) and mean diffusivity (MD)-in 12 thigh muscles, and architecture parameters-pennation angle, fascicle length, fiber curvature, and physiological cross-sectional area (PCSA)-in the rectus femoris (RF) and biceps femoris longus (BFL). Knee extension and flexion torques were also measured for comparison to architecture measures. FA and MD were associated with age (β = 0.33, p = 0.001, R2 = 0.10; and β = -0.36, p < 0.001, R2 = 0.12), and FA was negatively associated with Type I fiber proportions from the literature (β = -0.70, p = 0.024, and R2 = 0.43). Pennation angle, fiber curvature, fascicle length, and PCSA were associated with age in the RF (β = -0.22, 0.26, -0.23, and -0.31, respectively; p < 0.05), while in the BFL only curvature and fascicle length were associated with age (β = 0.36, and -0.40, respectively; p < 0.001). In the RF, pennation angle and PCSA were associated with strength (β = 0.29, and 0.46, respectively; p < 0.01); in the BFL, only PCSA was associated with strength (β = 0.43; p < 0.001). Our results show skeletal muscle architectural changes with aging and intermuscular differences in the microstructure. DT-MRI may prove useful for elucidating muscle changes in the early stages of sarcopenia and monitoring interventions aimed at preventing age-associated microstructural changes in muscle that lead to functional impairment.

Enhanced skeletal muscle contractile function and corticospinal excitability precede strength and architectural adaptations during lower-limb resistance training

PurposeEvolving investigative techniques are providing greater understanding about the early neuromuscular responses to resistance training among novice exercisers. The aim of this study was to investigate the time-course of changes in muscle contractile mechanics, architecture, neuromuscular, and strength adaptation during the first 6-weeks of lower-limb resistance training.MethodsForty participants: 22 intervention (10 males/12 females; 173.48 ± 5.20 cm; 74.01 ± 13.13 kg) completed 6-week resistance training, and 18 control (10 males/8 females; 175.52 ± 7.64 cm; 70.92 ± 12.73 kg) performed no resistance training and maintained their habitual activity. Radial muscle displacement (Dm) assessed via tensiomyography, knee extension maximal voluntary contraction (MVC), voluntary activation (VA), corticospinal excitability and inhibition via transcranial magnetic stimulation, motor unit (MU) firing rate, and muscle thickness and pennation angle via ultrasonography were assessed before and after 2, 4, and 6-weeks of dynamic lower-limb resistance training or control.ResultsAfter 2-weeks training, Dm reduced by 19–25% in the intervention group; this was before any changes in neural or morphological measures. After 4-weeks training, MVC increased by 15% along with corticospinal excitability by 16%; however, there was no change in VA, corticospinal inhibition, or MU firing rate. After 6-weeks training there was further MVC increase by 6% along with muscle thickness by 13–16% and pennation angle by 13–14%.ConclusionEnhanced contractile properties and corticospinal excitability occurred before any muscle architecture, neural, and strength adaptation. Later increases in muscular strength can be accounted for by architectural adaptation.

Dynamics of Changes in Muscle Architecture, Force, Strength-Velocity Properties of the Muscles of Lower Limbs in Humans under the Influence of a Three Week Unloading

The present study examined the hypothesis that significant alterations in antigravity muscle architecture would occur with dry water immersion (DI) and that some structural changes may be seen in postural muscles because of the overall decrease in physical activity. Ten men (age (mean ± SE) – 24.5 ± 3.9 years, height – 176.1 ± 1.2 m, mass – 71.1 ± 3.4 kg) volunteered for the study. The healthy men underwent of DI for 21 days. All subjects did not use physical training during the exposure. The contractile properties of the muscle ankle extensors and flexors (maximal voluntary contraction (MVC) and strength-velocity relationship) were evaluated using an isokinetic dynamometer. The internal architecture of the triceps surae muscle of its two heads (medial (MG) and lateral (LG) gastrocnemius muscles) was determined by in vivo ultrasound (US) at ankle angles of –15° (dorsiflexion), 0° (neutral anatomical position), and +30° (plantarflexion) with an angle in the knee joint of 0°. In each position, longitudinal US of MG and LG were obtained at the proximal levels 30% (MG and LG) of the distance between the popliteal crease and the center of the lateral malleolus. US images were detected at rest for each ankle position, and the fiber length (Lf) and pennation angle (Θf) relative to the aponeurosis were determined. After DI the MVC muscle ankle extensors decreased from 122.6 ± 43.1 to 99.5 ± 22.7 N (19%). Although there was a significant no change in dorsiflexion. After DI with the ankle angle increasing from –15° to +30°, Lf changes from 43 ± 1 to 32 ± 2 mm (25.6%, p 0.01) for MG and from 45 ± 2 to 34 ± 1 mm (24.4%, p 0.01) for LG, and Θf increased from 21° ± 1° to 26° ± 2° (23.8%) for MG and from 14° ± 1° to 18° ± 2° (28.6%) for LG. Collectively, the present data suggest that the architecture and contractile capacity of human pennate muscle are interrelated, in vivo. The finding that amongst the antigravity muscles, the MG deteriorated to a greater extent than the LG is possibly related to the differences in relative load that this muscle possibly experiences during daily loading. Different Lf and Θf, and their changes by after unloading, might be related to differences in force-producing capabilities of the muscles and elastic characteristics of tendons and aponeuroses. Structural muscle changes can be considered as an adaptive process, in response to disuse.

Agreement and reliability of lower limb muscle architecture measurements using a portable ultrasound device

Although ultrasonography is commonly used to assess muscle architecture, high-end ultrasonography devices lack in portability and are expensive. Recently, ultrasonography devices consisting solely of a probe, an app, and/or a mobile display were introduced. These devices have lower acquisition costs than high-end devices and demonstrate higher portability. Portable systems would allow for cost-effective, on-site athlete or patient screenings of muscle architecture as well as diagnosis of pathologies or injury. Furthermore, portable systems can be easily transported to allow for uncomplicated assessment of athletes belonging to different teams or patients in different hospital units. Nonetheless, the reliability of portable systems and the comparability to high-end devices for muscle architecture assessment have not been investigated.&#x0D; We investigated the agreement and reliability of a portable and handheld ultrasonography system for muscle architecture measurements in human lower limb muscles. We acquired images of the rectus femoris (RF), vastus lateralis (VL) and gastrocnemius medialis (GM) in 36 active healthy participants (15 female, 21 male) at 50% of muscle length using the handheld Lumify (L12-4, linear array 37 mm, Philips Healthcare, Amsterdam, Netherlands) and a high-end laboratory device (ACUSON Juniper, linear-array 54 mm, 12L3, SIEMENS Healthineers, Erlangen, Germany). Muscle length was determined as distance between the proximal and distal muscle tendon junction. We compared measurements of muscle fascicle length, pennation angle and thickness. To assess inter-session reliability of the Lumify system, participants were measured twice within 1 week.&#x0D; Comparing RF architecture measurements of both devices resulted in intra-class correlations (ICCs) ranging from 0.46–0.82 and standardized mean difference (SMDs) ranging from −0.45–0.05. For VL, ICCs ranged from 0.60–0.89 and SMDs ranged from −0.11–0.13. ICCs and SMDs for the GM ranged from 0.82–0.86 and −0.07–0.07. Calculating inter-session reliability for RF resulted in ICCs ranging from 0.44–0.76 and SMDs ranging from −0.38–0.15. For VL, ICCs and SMDs ranged from 0.57–0.75 and −0.13–0.02. ICCs for GM ranged from 0.75–0.92 and SMDs ranged from −0.15–0.16. The highest agreement (ICC ≥ 0.82) and reliability (ICC ≥ 0.75) across all muscles was demonstrated for the measurement of muscle thickness.&#x0D; The Lumify system was comparable to a high-end device and reliable for GM measurements. Nevertheless, agreement and reliability were lower for the RF and VL. Thus, when interpreting longitudinal observed changes in muscle architecture assessed with the Lumify system, measurement errors should be considered. Future investigations should consider including different participant populations, comparing the reliability of different portable systems for muscle architecture assessment as well as including different muscle groups.

Does Electrode Sensor Positioning over Motor Points Affect Different Portions of Quadriceps Muscle Architecture during Submaximal Evoked Torque?

Background and Objectives. Few studies have evaluated differences in muscle architecture in quadriceps femoris constituents with sensor electrodes positioned over vastus lateralis (VL) and vastus medialis (VM) motor points during a neuromuscular electrical stimulation (NMES) session. We aimed to investigate the changes in muscle architecture of the rectus femoris (RF), VL, VM, and vastus intermedius (VI) portions during evoked contractions with sensor electrodes placed over VL and VM motor points. Materials and Methods. The study is a crossover, repeated-measure design, conducted with healthy males aged 24.0 ± 4.6 years. Ultrasonography at rest and evoked contraction at 40% of maximum voluntary contraction (MVC) were used to assess the pennation angle ( θ p ) and fascicle length (Lf) of RF, VL, VM, and VI portions. Results. The mean torque observed was 201.14 ± 50.22 N.m during MVC and at 40% of MVC was 80.45 ± 20.08 N.m. There was no difference for θ p comparing four components of the quadriceps femoris ( p = 0.27 ). There was a significant ( p &lt; 0.05 ) muscle evoked contraction interaction for Lf without relevant clinical importance to the study. Conclusions. There is no difference in the changes in the muscle architecture of quadriceps femoris constituents during stimulation with the electrodes placed on the VL and VM motor points. Therefore, clinicians can choose either VL or VM motor points for sensor electrode positioning and expect similar muscle architecture adaptation for a given evoked torque. Future clinical studies should be conducted to establish the optimal electrode positioning over different portions of the quadriceps muscle to optimize more rational NMES clinical settings.

Acute Effects of Percussive Therapy on the Posterior Shoulder Muscles Differ Based on the Athlete's Soreness Response.

BackgroundPercussive therapy is hypothesized to speed recovery by delivering gentle, rhythmic pulses to soft tissue. However, patients often present with a differential soreness response after percussive therapy, which may lead to altered clinical outcomes.PurposeTo compare the acute effects of percussion therapy on passive range of motion (ROM) and tissue-specific ultrasound measures (pennation angle [PA] and muscle thickness [MT]) between healthy individuals responding positively vs. negatively to percussive therapy performed on the dominant arm posterior rotator cuff.Study DesignCross-sectional laboratory studyMethodsFifty-five healthy individuals were assessed on a subjective soreness scale before and after a five-minute percussive therapy session on the dominant arm posterior rotator cuff muscles. Participants with no change or a decrease in muscle soreness were assigned to the positive response group and participants who reported an increase in muscle soreness were assigned to the negative response group. Passive internal rotation (IR) and external rotation (ER) ROM and strength, and muscle architecture of the infraspinatus and teres minor were measured via ultrasound on the dominant shoulder. All dependent variables were collected before percussive therapy, and 20 minutes following percussive therapy.ResultsThe positive response group had greater improvements than the negative response group in dominant arm IR ROM (2.3° positive vs. -1.3° negative, p=0.021) and IR strength (1.1 lbs vs. -1.2 lbs, p=0.011) after percussive therapy. No differences in ER strength or ROM were observed between groups. Regarding muscle architecture, the positive group had a lesser change in teres minor MT (0.00 mm vs. 0.11 mm, p=0.019) after percussive therapy. All other muscle architecture changes were not statistically different between groups.ConclusionParticipants with a positive response to percussive therapy had increased dominant arm IR ROM and IR strength, and decreased teres minor MT, after percussive therapy compared to the negative response participants.Level of EvidenceIII

Ultrasound Assessment of Changes in Muscle Architecture of the Brachialis Muscle After Stroke—A Prospective Study

ObjectiveTo investigate changes in ultrasound-derived muscle architecture parameters of the brachialis and correlations in patients with subacute stroke. DesignProspective longitudinal observational study. SettingTertiary inpatient rehabilitation center. ParticipantsFifty adult patients (N=50) who were recruited within the first month poststroke. The patients had a mean age of 57.2±12.3 years and 68.0% were male. The majority of patients had significant upper limb weakness with a low mean Motricity Index of 18.5±24.7 and median elbow flexor strength of grade 0. InterventionNot applicable. Main Outcome MeasuresUltrasound of the intact and hemiparetic brachialis was performed at 3-time intervals: within 1 month of stroke onset and at 1 and 6 months after first assessment. Clinical variables captured included upper limb motor power and elbow flexor spasticity. ResultsCompared to the intact brachialis, there was reduced muscle thickness (1.93 cm vs 2.07 cm, 1.86 cm vs 2.08 cm, 1.85 cm vs 2.05 cm; P=.022) and increased echo intensity (63.3 arbitrary units [AU] vs 56.8 AU, 69.4 AU vs 56.6 AU, 77.4 AU vs 58.2 AU; P<.001) in the hemiparetic brachialis at all assessment intervals (baseline, 1 month, 6 months). Reduction in muscle mass was greater in older patients, with the correlation coefficient ranging from −0.30 (P=.03) at baseline to −0.50 (P<.001) at 6 months. Presence of elbow flexor spasticity at 1-month assessment interval was associated with lower muscle mass reduction (1.93 cm vs 1.74 cm; P=.017), lower echo intensity (65.1 AU vs 75.1 AU; P=.023), and longer fascicle lengths (12.92 cm vs 9.83 cm; P=.002). ConclusionsChanges including decreased muscle thickness and increased echo intensity of the hemiparetic brachialis were noted over time. Elbow flexor spasticity at 1-month assessment interval appears to mitigate against these changes.

Shoulder muscle changes in patients with type 2 diabetes mellitus who have a painful shoulder: a quantitative muscle ultrasound study

BackgroundIt is assumed that in patients with diabetic neuropathy, muscle denervation can result in shoulder disorders. Muscle denervation will lead to changes in muscle architecture, which can be assessed by quantitative muscle ultrasound (QMUS). The aim was to investigate whether increased muscle echogenicity, as a sign of neuropathy, is more often present in patients with shoulder pain who have type 2 diabetes mellitus (T2DM) than in those without.MethodsSixty-six patients with T2DM and 23 patients without diabetes mellitus (DM) having shoulder pain were included. Quantitative muscle ultrasound images were obtained bilaterally from the biceps brachii, deltoid, and supra- and infraspinatus muscles. The mean echogenicity (muscle ultrasound grey value) was transformed into z-scores and compared to reference values obtained from 50 healthy participants. Associations between muscle echogenicity and clinical variables were explored.ResultsIn painful shoulders of both patients with T2DM and patients without DM, mean echogenicity z-scores of all muscles were significantly increased compared to healthy controls. No significant differences in echogenicity between patients with T2DM and those without DM were found. In patients with T2DM, a distal symmetric polyneuropathy was significantly associated with increased echogenicity of all muscles except the infraspinatus muscle.ConclusionsThese findings indicate that patients with painful shoulders, irrespective of having T2DM, seem to have abnormal shoulder muscles. Future studies are needed to elucidate whether neuropathy or other conditions lead to these muscle changes.

Alterations in biogenic amines levels associated with age-related muscular tissue impairment in Drosophila melanogaster

While holding on youth may be a universal wish, aging is a natural process associated with physical and physiological impairment in living organisms. Drosophila provides useful insights into aging-related events. Hence, this study was conducted to investigate the age-related changes in muscle function and architecture in relation to the biogenic amine titers. To achieve this aim, visceral and skeletal muscles performance was tested in newly-eclosed, sexually mature and old adult flies using climbing and gut motility assays. In addition, age-related ultrastructural alterations of muscular tissue were observed using transmission electron microscopy (TEM). The titer of selected biogenic amines was measured using high-performance liquid chromatography (HPLC). The results demonstrated that old flies were dramatically slower in upward movement than either newly-eclosed or sexually mature flies. Similarly, gut contraction rate was significantly lower in old flies than the sexually mature, although it was markedly higher than that in the newly-eclosed flies. In TEM examination, there were several ultrastructural changes in the midgut epithelium, legs and thorax muscles of old flies. Regarding biogenic amine titers, the old flies had significantly lower concentrations of octopamine, dopamine and serotonin than the sexually mature. We concluded that aging has adverse effects on muscular system function and ultrastructure, synchronized with biogenic amine titers changes. Our results highlighted the need for more researches on therapeutics that may balance the levels of age-related alterations in biogenic amines.

Neuromuscular disorders in women and men with spinal cord injury are associated with changes in muscle and tendon architecture

Objective The present study aimed to determine the association between neuromuscular function, motor function impairment, and muscle and tendon structures in individuals with spinal cord injury (SCI) compared to a control (non-disabled) population. Design A cross-sectional study with a control group. Setting Center of Adapted Sports Training and Special Physical Education. Participants Fifteen individuals with SCI and motor function impairments participated in the study. A paired non-disabled group was recruited for comparison. Interventions Not applicable. Outcome measures Muscle (biceps brachii, rectus femoris, vastus lateralis, vastus medialis, and tibialis anterior) and tendon (quadriceps and patellar tendons) structures were assessed by ultrasound imaging (thickness, pennation angle, fascicle length, and echogenicity). Neuromuscular electrophysiological disorders were also assessed using electrodiagnosis techniques (stimulus non-responsivity and chronaxie) in the same muscles. Results Except for the biceps brachii muscle, muscle thickness, pennation angle, and fascicle length were lower (p < 0.01) while echogenicity and chronaxie were greater (p < 0.01) in SCI participants. The SCI participants had a higher prevalence of neuromuscular electrophysiological disorders for all muscles, except the biceps brachii. Conclusion Neuromuscular disorders occur in association with muscle and tendon maladaptation in individuals with chronic SCI. A higher prevalence of electrophysiological disorders suggests an acquired polyneuromyopathy for muscles with motor function impairment even though the muscle was innerved, in addition to widespread muscle atrophy.