Influence of Sex and Cross-Sectional Area on Motor Unit Recruitment Patterns of the Vastus Lateralis

To examine the hypothesis that increases in fiber cross-sectional area mediated by high-resistance training (HRT) would result in a decrease in fiber capillarization and oxidative potential, regardless of fiber type, we studied six untrained males (maximum oxygen consumption, 45.6 ± 2.3 ml ⋅ kg−1 ⋅ min−1; mean ± SE) participating in a 12-wk program designed to produce a progressive hypertrophy of the quadriceps muscle. The training sessions, which were conducted 3 times/wk, consisted of three sets of three exercises, each performed for 6–8 repetitions maximum (RM). Measurements of fiber-type distribution obtained from tissue extracted from the vastus lateralis at 0, 4, 7, and 12 wk indicated reductions ( P < 0.05) in type IIB fibers (15.1 ± 2.1% vs. 7.2 ± 1.3%) by 4 wk in the absence of changes in the other fiber types (types I, IIA, and IIAB). Training culminated in a 17% increase ( P < 0.05) in cross-sectional area by 12 wk with initial increases observed at 4 wk. The increase was independent of fiber type-specific changes. The number of capillaries in contact with each fiber type increased by 12 wk, whereas capillary contacts-to-fiber area ratios remained unchanged. In a defined cross-sectional field, HRT also increased the capillaries per fiber at 12 wk. Training failed to alter cellular oxidative potential, as measured by succinic dehydrogenase (SDH) activity, regardless of fiber type and training duration. It is concluded that modest hypertrophy induced by HRT does not compromise cellular tissue capillarization and oxidative potential regardless of fiber type.

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Intra- and inter-muscular differences in the cross-sectional area of the quadriceps muscles assessed by extended field-of-view ultrasonography

Medical Ultrasonography ◽

10.11152/mu-2302 ◽

2020 ◽

Vol 22 (2) ◽

pp. 152 ◽

Cited By ~ 2

Author(s):

Chrysostomos Sahinis ◽

Eleftherios Kellis ◽

Nikiforos Galanis ◽

Konstantinos Dafkou ◽

Athanasios Ellinoudis

Keyword(s):

Vastus Lateralis ◽

Intraclass Correlation ◽

Cross Sectional Area ◽

Field Of View ◽

Cost Evaluation ◽

Sectional Area ◽

Cross Sectional ◽

Vastus Intermedius ◽

Extended Field ◽

Extended Field Of View

Aim: Τo examine the inter- and intra-muscular differences in the anatomical cross-sectional area (CSA) of the quadricep muscles, using extended - field of view (EFOV) ultrasonography (US).Material and methods: Panoramic transverse US images of the thigh were acquired from 10 young participants at five different locations across the thigh, in two sessions, spaced a week apart. The CSA of the vastus medialis (VM), rectus femoris (RF), vastus intermedius (VI), vastus lateralis (VL) and tensor vastus intermedius (TVI) was quantified.Results: The intraclass correlation coefficients ranged from 0.75 to 0.97 and the standard error of measurement ranged from 0.78% to 6.61%, indicating high test-retest reliability. Analysis of the variance indicated that among the 5 quadriceps muscles the VL and the RF displayed the greater CSA proximally, the VI medially and the VM distally across the thigh (p <0.05). No differences in the quadriceps CSA measured with and without including the TVI were found (p >0.05).Conclusions: The EFOV US technique provides transverse scans of the quadriceps muscle in vivo and allowed a reliable and non-invasive determination of CSA at a low cost. Evaluation of CSA along the thigh largely depends on the measurement site. Future studies that examine the quadriceps CSA using EFOV after any form of intervention should consider changes of at least 6.5% as meaningful.

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Maximal force as a function of anatomical features of motor units in the cat tibialis anterior

Journal of Neurophysiology ◽

10.1152/jn.1987.57.6.1730 ◽

1987 ◽

Vol 57 (6) ◽

pp. 1730-1745 ◽

Cited By ~ 99

Author(s):

S. C. Bodine ◽

R. R. Roy ◽

E. Eldred ◽

V. R. Edgerton

Keyword(s):

Motor Unit ◽

Tibialis Anterior ◽

Periodic Acid ◽

Muscle Fibers ◽

Motor Units ◽

Cross Sectional Area ◽

Sectional Area ◽

Periodic Acid Schiff ◽

Cross Sectional ◽

Single Motor Unit

In 11 tibialis anterior muscles of the cat, a single motor unit was characterized physiologically and subsequently depleted of its glycogen through repetitive stimulation of an isolated ventral root filament. Muscle cross sections were stained for glycogen using a periodic acid-Schiff reaction, and single-fiber optical densities were determined to identify those fibers belonging to the stimulated motor unit. Innervation ratios were determined by counting the total number of muscle fibers in a motor unit in sections taken through several levels of the muscle. The average innervation ratios for the fast, fatigueable (FF) and fast, fatigue-resistant (FR) units were similar. However, the slow units (S) contained 61% fewer fibers than the fast units (FF and FR). Muscle fibers belonging to S and FR units were similar in cross-sectional area, whereas fibers belonging to FF units were significantly larger than fibers belonging to either S or FR units. Additionally, muscle fibers innervated by a single motoneuron varied by two- to eightfold in cross-sectional area. Specific tensions, based on total cross-sectional area determined by summing the areas of all muscle fibers of each unit, showed a modest difference between fast and slow units, the means being 23.5 and 17.2 N X cm-2, respectively. Variations in maximum tension among units could be explained principally by innervation ratio, although fiber cross-sectional area and specific tension did contribute to differences between unit types.

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Effects of sprint cycle training on human skeletal muscle

Journal of Applied Physiology ◽

10.1152/jappl.1994.77.5.2385 ◽

1994 ◽

Vol 77 (5) ◽

pp. 2385-2390 ◽

Cited By ~ 64

Author(s):

C. A. Allemeier ◽

A. C. Fry ◽

P. Johnson ◽

R. S. Hikida ◽

F. C. Hagerman ◽

...

Keyword(s):

Fiber Type ◽

Vastus Lateralis ◽

Cross Sectional Area ◽

Aerobic Performance ◽

Vastus Lateralis Muscle ◽

Sectional Area ◽

Cross Sectional ◽

Fast Fiber ◽

Cycle Training ◽

Exercise Induced

Eleven men sprint trained two to three times per week for 6 wk to investigate possible exercise-induced slow-to-fast fiber type conversions. Six individuals served as controls. Both groups were tested at the beginning and end of the study to determine anaerobic performance and maximal oxygen consumption. In addition, pre- and postbiopsies were extracted from the vastus lateralis muscle and were analyzed for fiber type composition, cross-sectional area, and myosin heavy chain (MHC) content. No significant changes were found in anaerobic or aerobic performance variables for either group. Although a trend was found for a decrease in the percentage of type IIb fibers, high-intensity sprint cycle training caused no significant changes in the fiber type distribution or cross-sectional area. However, the training protocol did result in a significant decrease in MHC IIb with a concomitant increase in MHC IIa for the training men. These data appear to support previous investigations that have suggested exercise-induced adaptations within the fast fiber population (IIb-->IIa) after various types of training (endurance and strength).

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The Effect of ACL Reconstruction on Involved and Contralateral Limb Vastus Lateralis Morphology and Histology: A Pilot Study

The Journal of Knee Surgery ◽

10.1055/s-0039-1697899 ◽

2019 ◽

Author(s):

Eric C. Leszczynski ◽

Christopher Kuenze ◽

Brett Brazier ◽

Joseph Visker ◽

David P. Ferguson

Keyword(s):

Fiber Type ◽

Vastus Lateralis ◽

Knee Extension ◽

Cross Sectional Area ◽

Vastus Lateralis Muscle ◽

Myosin Isoforms ◽

Sectional Area ◽

Cross Sectional ◽

Contralateral Limb ◽

Significant Difference

AbstractQuadriceps muscle weakness is a commonly reported issue post anterior cruciate ligament reconstruction (ACLR), with minimal information related to skeletal muscle morphology following surgery. The purpose is to examine the morphological and functional differences in the vastus lateralis muscle from patient's ACLR and contralateral leg. Three physically active ACLR participants were recruited and secured to a dynamometer to perform maximal voluntary isometric knee extension contractions (MVIC) of the ACLR and contralateral limb. Muscle biopsies of the ACLR and contralateral vastus lateralis were performed, then sectioned, and stained for myosin isoforms to determine fiber type. Confocal images were acquired, and ImageJ software was used to determine the fiber type and cross-sectional area (CSA). There was a significant reduction in CSA of the type IIa and type IIx muscle fiber cells between healthy (IIa: 7,718 ± 1,295 µm2; IIx; 5,800 ± 601 µm2) and ACLR legs (IIa: 4,139 ± 709 µm2; IIx: 3,708 ± 618 µm2) (p < 0.05), while there was no significant difference in knee extension MVIC torque between legs (healthy limb: 2.42 ± 0.52 Nm/kg; ACLR limb: 2.05 ± 0.24 Nm/kg, p = 0.11). The reduction in the cross-sectional area of the ACLR type II fibers could impair function and increase secondary injury risk.

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Bilateral Differences in Muscle Architecture and Increased Rate of Injury in National Basketball Association Players

Journal of Athletic Training ◽

10.4085/1062-6050-49.3.60 ◽

2014 ◽

Vol 49 (6) ◽

pp. 794-799 ◽

Cited By ~ 17

Author(s):

Gerald T. Mangine ◽

Jay R. Hoffman ◽

Adam M. Gonzalez ◽

Adam R. Jajtner ◽

Tyler Scanlon ◽

...

Keyword(s):

Lower Extremity ◽

Vastus Lateralis ◽

Muscle Thickness ◽

Cross Sectional Area ◽

Lower Extremity Injury ◽

Sectional Area ◽

Basketball Players ◽

Cross Sectional ◽

Professional Basketball ◽

Bilateral Differences

Context Professional basketball players have demanding schedules that, in combination with certain underlying physical characteristics and side-to-side strength and power imbalances, may make them vulnerable to lower extremity injuries. Objective To examine the relationship among skeletal muscle architecture, lower body power, and games missed because of lower extremity injury (%MISS) in professional basketball players. Design Cross-sectional study. Setting Human Performance Laboratory. Patients or Other Participants Nine players under contract for Orlando Magic were assessed. We compared athletes who were injured (n = 4, height = 203.2 ± 5.5 cm, mass = 105 ± 7.5 kg, age = 25.0 ± 2.8 years) and those who remained healthy (n = 5, height = 200.2 ± 12.2 cm, mass = 100.1 ± 16.6 kg, age = 22.4 ± 1.9 years) during the season. Main Outcome Measure(s) Bilateral ultrasonographic measurements of muscle thickness, pennation angle, echo intensity, and cross-sectional area of the rectus femoris and vastus lateralis were collected before regular-season play. Subsequently, muscle thickness and pennation angle were used to compute fascicle length. Along with unilateral jumping power, inferences were made upon the magnitude of the relationship between the percentage bilateral difference in these measures and %MISS, as well as between injured and healthy athletes. Results The data indicated likely relationships between %MISS and age (r = 0.772), and between %MISS and bilateral differences in rectus femoris cross-sectional area (7.8% ± 6.4%; r = 0.657) and vastus lateralis cross-sectional area (6.2% ± 4.8%; r = 0.521), as well as a possible relationship with vastus lateralis muscle thickness (7.9% ± 8.9%; r = 0.444). Echo-intensity differences in the vastus lateralis were greater in injured (8.0% ± 2.4%) versus healthy athletes (3.2% ± 2.0%). Although a 2-fold difference in mean jumping power was observed between injured (26.3 ± 14.9 W) and healthy athletes (13.6 ± 8.7 W), these differences were not statistically significant (P = .20). Conclusions In the present sample, lower extremity side-to-side differences may be related to an increased risk for lower extremity injury. Future researchers using larger sample sizes need to identify normal versus at-risk ranges for bilateral differences in muscle structure and power of the lower extremities of professional basketball players and athletes in other sports.

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DeepACSA: Automatic segmentation of anatomical cross-sectional area in ultrasound images of human lower limb muscles using deep learning

10.1101/2021.12.27.21268258 ◽

2021 ◽

Author(s):

Paul Ritsche ◽

Philipp Wirth ◽

Neil Cronin ◽

Fabio Sarto ◽

Marco Narici ◽

...

Keyword(s):

Deep Learning ◽

Lower Limb ◽

Vastus Lateralis ◽

Rectus Femoris ◽

Cross Sectional Area ◽

Mean Difference ◽

Ultrasound Images ◽

Sectional Area ◽

Cross Sectional ◽

Manual Analysis

Background: Muscle anatomical cross-sectional area (ACSA) is an important parameter that characterizes muscle function and helps to classify the severity of several muscular disorders. Ultrasound is a patient friendly, fast and cheap method of assessing muscle ACSA, but manual analysis of the images is laborious, subjective and requires thorough experience. To date, no open access and fully automated program to segment ACSA in ultrasound images is available. On this basis, we present DeepACSA, a deep learning approach to automatically segment ACSA in panoramic ultrasound images of the human rectus femoris (RF), vastus lateralis (VL), gastrocnemius medialis (GM) and lateralis (GL) muscles. Methods: We trained convolutional neural networks using 1772 ultrasound images from 153 participants (25 females, 128 males; mean age = 38.2 years, range: 13-78) captured by three experienced operators using three distinct devices. We trained three muscle-specific models to detect ACSA. Findings: Comparing DeepACSA analysis of the RF to manual analysis resulted in intra-class correlation (ICC) of 0.96 (95% CI 0.94,0.97), mean difference of 0.31 cm2 (0.04,0.58) and standard error of the differences (SEM) of 0.91 cm2 (0.47,1.36). For the VL, ICC was 0.94 (0.91,0.96), mean difference was 0.25 cm2 (-0.21,0.7) and SEM was 1.55 cm2 (1.13,1.96). The GM/GL muscles demonstrated an ICC of 0.97 (0.95,0.98), a mean difference of 0.01 cm2 (-0.25, 0.24) and a SEM of 0.69 cm2 (0.52,0.83). Interpretation: DeepACSA provides fast and objective segmentation of lower limb panoramic ultrasound images comparable to manual segmentation and is easy to implement both in research and clinical settings. Inaccurate model predictions occurred predominantly on low-quality images, highlighting the importance of high image quality for accurate prediction.

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Skeletal Muscle Composition and Glucose Levels in Children Who Are Overweight and Obese

Pediatric Exercise Science ◽

10.1123/pes.2020-0018 ◽

2020 ◽

Vol 32 (3) ◽

pp. 157-164

Author(s):

Trent J. Herda ◽

Philip M. Gallagher ◽

Jonathan D. Miller ◽

Matthew P. Bubak ◽

Mandy E. Parra

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Vastus Lateralis ◽

Rectus Femoris ◽

Cross Sectional Area ◽

First Dorsal Interosseous ◽

Sectional Area ◽

Cross Sectional ◽

Muscle Composition ◽

Glucose Levels

Background: Skeletal muscle is overlooked in the realm of insulin resistance in children who are overweight and obese despite the fact that it accounts for the most glucose disposal. Objectives: Therefore, this study examined fasted glucose levels and muscle cross-sectional area and echo intensity (EI) via ultrasound images of the first dorsal interosseous, vastus lateralis, and rectus femoris in children who are normal weight and overweight and obese aged 8–10 years. Methods: In total, 13 males (age = 9.0 [0.7] y) and 7 females (age = 9.0 [0.8] y) volunteered for this study. Independent samples t tests and effect sizes (ESs) were used to examine potential differences in skeletal muscle composition and glucose concentrations. Results: There were no significant differences between groups for glucose concentration (P = .07, ES = 0.86); however, the children who were overweight and obese had significantly greater EI (P < .01, ES = 0.98–1.63) for the first dorsal interosseous, vastus lateralis, and rectus femoris and lower cross-sectional area when normalized to EI when collapsed across muscles (P < .04, ES = 0.92). Glucose concentrations correlated with EI and cross-sectional area/EI for the vastus lateralis (r = .514 to −.593) and rectus femoris (r = .551 to −.513), but not the first dorsal interosseous. Discussion: There is evidence that adiposity-related pathways leading to insulin resistance and skeletal muscle degradation are active in young children who are overweight and obese.

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