Muscle Quality, Architecture, and Activation in Cachectic Patients with Rheumatoid Arthritis

Objective. To explore muscle-specific force (force per physiological cross-sectional area, or PCSA) and muscle activation in cachectic patients with rheumatoid arthritis (RA).Methods. In 14 muscle-wasted patients with RA and age and sex matched healthy controls, vastus lateralis (VL) force and voluntary activation capacity were assessed during maximal isometric contractions with electromyography and superimposed electrical stimulations. VL PCSA was determined from ultrasound measures of fiber fascicle length (Lf), pennation angle, and volume, together with assessments of body composition by dual energy x-ray absorptiometry and objective physical function.Results. Although patients with RA had reduced physical function, lower muscle mass, and VL volume relative to controls, there were no differences in muscle-specific force and activation. PCSA, force, and pennation angle tended to be lower in RA, with no differences in Lf.Conclusion. Muscle-specific force and activation are not compromised and thus are unlikely to contribute to reduced function in cachectic patients with RA.

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Differences in Pedaling Technique in Cycling: A Cluster Analysis

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2015-0142 ◽

2016 ◽

Vol 11 (7) ◽

pp. 959-964

Author(s):

Fábio J. Lanferdini ◽

Rodrigo R. Bini ◽

Pedro Figueiredo ◽

Fernando Diefenthaeler ◽

Carlos B. Mota ◽

...

Keyword(s):

Cluster Analysis ◽

Power Output ◽

Muscle Activation ◽

Vastus Lateralis ◽

Unit Length ◽

Muscle Thickness ◽

Pennation Angle ◽

Fascicle Length ◽

Pedal Force ◽

Cluster 2

Purpose:To employ cluster analysis to assess if cyclists would opt for different strategies in terms of neuromuscular patterns when pedaling at the power output of their second ventilatory threshold (POVT2) compared with cycling at their maximal power output (POMAX).Methods:Twenty athletes performed an incremental cycling test to determine their power output (POMAX and POVT2; first session), and pedal forces, muscle activation, muscle–tendon unit length, and vastus lateralis architecture (fascicle length, pennation angle, and muscle thickness) were recorded (second session) in POMAX and POVT2. Athletes were assigned to 2 clusters based on the behavior of outcome variables at POVT2 and POMAX using cluster analysis.Results:Clusters 1 (n = 14) and 2 (n = 6) showed similar power output and oxygen uptake. Cluster 1 presented larger increases in pedal force and knee power than cluster 2, without differences for the index of effectiveness. Cluster 1 presented less variation in knee angle, muscle–tendon unit length, pennation angle, and tendon length than cluster 2. However, clusters 1 and 2 showed similar muscle thickness, fascicle length, and muscle activation. When cycling at POVT2 vs POMAX, cyclists could opt for keeping a constant knee power and pedal-force production, associated with an increase in tendon excursion and a constant fascicle length.Conclusions:Increases in power output lead to greater variations in knee angle, muscle–tendon unit length, tendon length, and pennation angle of vastus lateralis for a similar knee-extensor activation and smaller pedal-force changes in cyclists from cluster 2 than in cluster 1.

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Gastrocnemius muscle specific force in boys and men

Journal of Applied Physiology ◽

10.1152/japplphysiol.00697.2007 ◽

2008 ◽

Vol 104 (2) ◽

pp. 469-474 ◽

Cited By ~ 45

Author(s):

Christopher I. Morse ◽

Keith Tolfrey ◽

Jeanette M. Thom ◽

Vasilios Vassilopoulos ◽

Constantinos N. Maganaris ◽

...

Keyword(s):

Muscle Activation ◽

Muscle Length ◽

Tanner Stage ◽

Surface Emg ◽

Specific Force ◽

Moment Arm ◽

Fascicle Length ◽

Cross Sectional ◽

Adult Men

The aim of this study was to assess whether the in vivo specific force and architectural characteristics of the lateral gastrocnemius (GL) muscle of early pubescent boys ( n = 11, age = 10.9 ± 0.3 yr, Tanner stage 2) differed from those of adult men ( n = 12, age = 25.3 ± 4.4 yr). Plantarflexor torque was 55% lower in the boys (77.4 ± 21.4 N·m) compared with the adults (175.6 ± 31.7 N·m, P < 0.01). Physiological cross-sectional area (PCSA), determined in vivo using ultrasonography and MRI, was 52% smaller in the boys ( P < 0.01). No difference was found in pennation angle, or in the ratio of fascicle length ( Lf) to muscle length between the boys and men. Moment arm length was 25% smaller in the boys ( P < 0.01). Antagonist coactivation, assessed using surface EMG on the dorsiflexors, was not different between the boys and men (11.8 ± 6.7% and 13.5 ± 5.8%, respectively). Surprisingly, GL force normalized to PCSA (specific force) was significantly higher (21%) in the boys than in the men (13.1 ± 2.0 vs. 15.9 ± 2.7 N/cm2, P < 0.05). This finding could not be explained by differences in moment arm length, muscle activation, or architecture, and other factors, such as tendinous characteristics and/or changes in moment arm length with contraction, may be held responsible. These observations warrant further investigation.

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Patient education, disease activity and physical function: can we be more targeted? A cross sectional study among people with rheumatoid arthritis, psoriatic arthritis and hand osteoarthritis

Arthritis Research & Therapy ◽

10.1186/ar4339 ◽

2013 ◽

Vol 15 (5) ◽

pp. R156 ◽

Cited By ~ 29

Author(s):

Răzvan G Drăgoi ◽

Mwidimi Ndosi ◽

Martina Sadlonova ◽

Jackie Hill ◽

Mona Duer ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

Psoriatic Arthritis ◽

Patient Education ◽

Disease Activity ◽

Physical Function ◽

Cross Sectional Study ◽

Hand Osteoarthritis ◽

Sectional Study ◽

Cross Sectional

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Central excitability does not limit postfatigue voluntary activation of quadriceps femoris

Journal of Applied Physiology ◽

10.1152/japplphysiol.01347.2005 ◽

2006 ◽

Vol 100 (6) ◽

pp. 1757-1764 ◽

Cited By ~ 45

Author(s):

J. M. Kalmar ◽

E. Cafarelli

Keyword(s):

Evoked Potentials ◽

Repeated Measures ◽

Muscle Activation ◽

Motor Evoked Potentials ◽

Vastus Lateralis ◽

Central Fatigue ◽

Knee Extension ◽

Voluntary Activation ◽

Fatigue Protocol ◽

Central Excitability

After fatigue, motor evoked potentials (MEP) elicited by transcranial magnetic stimulation and cervicomedullary evoked potentials elicited by stimulation of the corticospinal tract are depressed. These reductions in corticomotor excitability and corticospinal transmission are accompanied by voluntary activation failure, but this may not reflect a causal relationship. Our purpose was to determine whether a decline in central excitability contributes to central fatigue. We hypothesized that, if central excitability limits voluntary activation, then a caffeine-induced increase in central excitability should offset voluntary activation failure. In this repeated-measures study, eight men each attended two sessions. Baseline measures of knee extension torque, maximal voluntary activation, peripheral transmission, contractile properties, and central excitability were made before administration of caffeine (6 mg/kg) or placebo. The amplitude of vastus lateralis MEPs elicited during minimal muscle activation provided a measure of central excitability. After a 1-h rest, baseline measures were repeated before, during, and after a fatigue protocol that ended when maximal voluntary torque declined by 35% (Tlim). Increased prefatigue MEP amplitude ( P = 0.055) and cortically evoked twitch ( P < 0.05) in the caffeine trial indicate that the drug increased central excitability. In the caffeine trial, increased MEP amplitude was correlated with time to task failure ( r = 0.74, P < 0.05). Caffeine potentiated the MEP early in the fatigue protocol ( P < 0.05) and offset the 40% decline in placebo MEP ( P < 0.05) at Tlim. However, this was not associated with enhanced maximal voluntary activation during fatigue or recovery, demonstrating that voluntary activation is not limited by central excitability.

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Nature of the coupling between neural drive and force-generating capacity in the human quadriceps muscle

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1908 ◽

2015 ◽

Vol 282 (1819) ◽

pp. 20151908 ◽

Cited By ~ 22

Author(s):

François Hug ◽

Clément Goupille ◽

Daniel Baum ◽

Brent J. Raiteri ◽

Paul W. Hodges ◽

...

Keyword(s):

Muscle Force ◽

Vastus Lateralis ◽

Quadriceps Muscle ◽

Myoelectric Activity ◽

Neural Drive ◽

Fascicle Length ◽

Cross Sectional ◽

Muscle Fascicle ◽

Generating Capacity ◽

The Relationship

The force produced by a muscle depends on both the neural drive it receives and several biomechanical factors. When multiple muscles act on a single joint, the nature of the relationship between the neural drive and force-generating capacity of the synergistic muscles is largely unknown. This study aimed to determine the relationship between the ratio of neural drive and the ratio of muscle force-generating capacity between two synergist muscles (vastus lateralis (VL) and vastus medialis (VM)) in humans. Twenty-one participants performed isometric knee extensions at 20 and 50% of maximal voluntary contractions (MVC). Myoelectric activity (surface electromyography (EMG)) provided an index of neural drive. Physiological cross-sectional area (PCSA) was estimated from measurements of muscle volume (magnetic resonance imaging) and muscle fascicle length (three-dimensional ultrasound imaging) to represent the muscles' force-generating capacities. Neither PCSA nor neural drive was balanced between VL and VM. There was a large ( r = 0.68) and moderate ( r = 0.43) correlation between the ratio of VL/VM EMG amplitude and the ratio of VL/VM PCSA at 20 and 50% of MVC, respectively. This study provides evidence that neural drive is biased by muscle force-generating capacity, the greater the force-generating capacity of VL compared with VM, the stronger bias of drive to the VL.

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Quality over quantity? Association of skeletal muscle myosteatosis and myofibrosis on physical function in chronic kidney disease

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gfy139 ◽

2018 ◽

Vol 34 (8) ◽

pp. 1344-1353 ◽

Cited By ~ 12

Author(s):

Thomas J Wilkinson ◽

Douglas W Gould ◽

Daniel G D Nixon ◽

Emma L Watson ◽

Alice C Smith

Keyword(s):

Chronic Kidney Disease ◽

Kidney Disease ◽

Physical Function ◽

Physical Performance ◽

Rating Scale ◽

Handgrip Strength ◽

Rectus Femoris ◽

Muscle Quality ◽

Muscle Size ◽

Cross Sectional

Abstract Background Chronic kidney disease (CKD) is characterized by adverse changes in body composition, which are associated with poor clinical outcome and physical functioning. Whilst size is the key for muscle functioning, changes in muscle quality specifically increase in intramuscular fat infiltration (myosteatosis) and fibrosis (myofibrosis) may be important. We investigated the role of muscle quality and size on physical performance in non-dialysis CKD patients. Methods Ultrasound (US) images of the rectus femoris (RF) were obtained. Muscle quality was assessed using echo intensity (EI), and qualitatively using Heckmatt’s visual rating scale. Muscle size was obtained from RF cross-sectional area (RF-CSA). Physical function was measured by the sit-to-stand-60s (STS-60) test, incremental (ISWT) and endurance shuttle walk tests, lower limb and handgrip strength, exercise capacity (VO2peak) and gait speed. Results A total of 61 patients (58.5 ± 14.9 years, 46% female, estimated glomerular filtration rate 31.1 ± 20.2 mL/min/1.73 m2) were recruited. Lower EI (i.e. higher muscle quality) was significantly associated with better physical performance [STS-60 (r = 0.363) and ISWT (r = 0.320)], and greater VO2peak (r = 0.439). The qualitative rating was closely associated with EI values, and significant differences in function were seen between the ratings. RF-CSA was a better predictor of performance than muscle quality. Conclusions In CKD, increased US-derived EI was negatively correlated with physical performance; however, muscle size remains the largest predictor of physical function. Therefore, in addition to the loss of muscle size, muscle quality should be considered an important factor that may contribute to deficits in mobility and function in CKD. Interventions such as exercise could improve both of these factors.

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In vivo physiological cross-sectional area and specific force are reduced in the gastrocnemius of elderly men

Journal of Applied Physiology ◽

10.1152/japplphysiol.01186.2004 ◽

2005 ◽

Vol 99 (3) ◽

pp. 1050-1055 ◽

Cited By ~ 138

Author(s):

Christopher I. Morse ◽

Jeanette M. Thom ◽

Neil D. Reeves ◽

Karen M. Birch ◽

Marco V. Narici

Keyword(s):

Achilles Tendon ◽

Voluntary Contraction ◽

Pennation Angle ◽

Specific Force ◽

Plantar Flexor ◽

Moment Arm ◽

Plantar Flexors ◽

Elderly Men ◽

Cross Sectional

Sarcopenia and muscle weakness are well-known consequences of aging. The aim of the present study was to ascertain whether a decrease in fascicle force (Ff) could be accounted for entirely by muscle atrophy. In vivo physiological cross-sectional area (PCSA) and specific force (Ff/PCSA) of the lateral head of the gastrocnemius (GL) muscle were assessed in a group of elderly men [EM, aged 73.8 yr (SD 3.5), height 173.4 cm (SD 4.4), weight 78.4 kg (SD 8.3); means (SD)] and for comparison in a group of young men [YM, aged 25.3 yr (SD 4.4), height 176.4 cm (SD 7.7), weight 79.1 kg (SD 11.9)]. GL muscle volume (Vol) and Achilles tendon moment arm length were evaluated using magnetic resonance imaging. Pennation angle and fiber fascicle length (Lf) were measured using B-mode ultrasonography during isometric maximum voluntary contraction of the plantar flexors. PCSA was estimated as Vol/Lf. GL Ff was calculated by dividing Achilles tendon force by the cosine of θ, during the interpolation of a supramaximal doublet, and accounting for antagonist activation level (assessed using EMG), Achilles tendon moment arm length, and the relative PCSA of the GL within the plantar flexor group. Voluntary activation of the plantar flexors was lower in the EM than in the YM (86 vs. 98%, respectively, P < 0.05). Compared with the YM, plantar flexor maximal voluntary contraction torque and Ff of the EM were lower by 47 and 40%, respectively ( P < 0.01). Both Vol and PCSA were smaller in the EM by 28% ( P < 0.01) and 16% ( P < 0.05), respectively. Also, pennation angle was 12% smaller in the EM, whereas there was no significant difference in Lf between the YM and EM. After accounting for differences in agonists and antagonists activation, the Ff/PCSA of the EM was 30% lower than that of the YM ( P < 0.01). These findings demonstrate that the loss of muscle strength with aging may be explained not only by a reduction in voluntary drive to the muscle, but mostly by a decrease in intrinsic muscle force. This phenomenon may possibly be due to a reduction in single-fiber specific tension.

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Three-dimensional geometrical changes of the human tibialis anterior muscle and its central aponeurosis measured with three-dimensional ultrasound during isometric contractions

PeerJ ◽

10.7717/peerj.2260 ◽

2016 ◽

Vol 4 ◽

pp. e2260 ◽

Cited By ~ 36

Author(s):

Brent J. Raiteri ◽

Andrew G. Cresswell ◽

Glen A. Lichtwark

Keyword(s):

Three Dimensional ◽

Muscle Length ◽

Pennation Angle ◽

Human Muscle ◽

Muscle Fibres ◽

Isometric Contractions ◽

Fascicle Length ◽

Cross Sectional ◽

Shape Changes

Background.Muscles not only shorten during contraction to perform mechanical work, but they also bulge radially because of the isovolumetric constraint on muscle fibres. Muscle bulging may have important implications for muscle performance, however quantifying three-dimensional (3D) muscle shape changes in human muscle is problematic because of difficulties with sustaining contractions for the duration of anin vivoscan. Although two-dimensional ultrasound imaging is useful for measuring local muscle deformations, assumptions must be made about global muscle shape changes, which could lead to errors in fully understanding the mechanical behaviour of muscle and its surrounding connective tissues, such as aponeurosis. Therefore, the aims of this investigation were (a) to determine the intra-session reliability of a novel 3D ultrasound (3DUS) imaging method for measuringin vivohuman muscle and aponeurosis deformations and (b) to examine how contraction intensity influencesin vivohuman muscle and aponeurosis strains during isometric contractions.Methods.Participants (n= 12) were seated in a reclined position with their left knee extended and ankle at 90° and performed isometric dorsiflexion contractions up to 50% of maximal voluntary contraction. 3DUS scans of the tibialis anterior (TA) muscle belly were performed during the contractions and at rest to assess muscle volume, muscle length, muscle cross-sectional area, muscle thickness and width, fascicle length and pennation angle, and central aponeurosis width and length. The 3DUS scan involved synchronous B-mode ultrasound imaging and 3D motion capture of the position and orientation of the ultrasound transducer, while successive cross-sectional slices were captured by sweeping the transducer along the muscle.Results.3DUS was shown to be highly reliable across measures of muscle volume, muscle length, fascicle length and central aponeurosis length (ICC ≥ 0.98, CV < 1%). The TA remained isovolumetric across contraction conditions and progressively shortened along its line of action as contraction intensity increased. This caused the muscle to bulge centrally, predominantly in thickness, while muscle fascicles shortened and pennation angle increased as a function of contraction intensity. This resulted in central aponeurosis strains in both the transverse and longitudinal directions increasing with contraction intensity.Discussion.3DUS is a reliable and viable method for quantifying multidirectional muscle and aponeurosis strains during isometric contractions within the same session. Contracting muscle fibres do work in directions along and orthogonal to the muscle’s line of action and central aponeurosis length and width appear to be a function of muscle fascicle shortening and transverse expansion of the muscle fibres, which is dependent on contraction intensity. How factors other than muscle force change the elastic mechanical behaviour of the aponeurosis requires further investigation.

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Evaluation of the Lower Limb Muscles’ Electromyographic Activity during the Leg Press Exercise and Its Variants: A Systematic Review

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17134626 ◽

2020 ◽

Vol 17 (13) ◽

pp. 4626

Author(s):

Isabel Martín-Fuentes ◽

José M. Oliva-Lozano ◽

José M. Muyor

Keyword(s):

Muscle Activation ◽

Vastus Lateralis ◽

Muscular Activity ◽

Rectus Femoris ◽

Biceps Femoris ◽

Quadriceps Muscle ◽

Electromyographic Activity ◽

Full Extension ◽

Cross Sectional ◽

Leg Press

The aim of this study was to analyze the literature on muscle activation measured by surface electromyography (sEMG) of the muscles recruited when performing the leg press exercise and its variants. The Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to report this review. The search was carried out using the PubMed, Scopus, and Web of Science electronic databases. The articles selected met the following inclusion criteria: (a) a cross-sectional or longitudinal study design; (b) neuromuscular activation assessed during the leg press exercise, or its variants; (c) muscle activation data collected using sEMG; and (d) study samples comprising healthy and trained participants. The main findings indicate that the leg press exercise elicited the greatest sEMG activity from the quadriceps muscle complex, which was shown to be greater as the knee flexion angle increased. In conclusion, (1) the vastus lateralis and vastus medialis elicited the greatest muscle activation during the leg press exercise, followed closely by the rectus femoris; (2) the biceps femoris and the gastrocnemius medialis showed greater muscular activity as the knee reached full extension, whereas the vastus lateralis and medialis, the rectus femoris, and the tibialis anterior showed a decreasing muscular activity pattern as the knee reached full extension; (3) evidence on the influence of kinematics modifications over sEMG during leg press variants is still not compelling as very few studies match their findings.

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