scholarly journals CORRELATION BETWEEN MAXIMAL FORCE AND CROSS SECTIONAL AREA IN TYPE I & IIA SINGLE MUSCLE FIBERS

1998 ◽  
Vol 30 (Supplement) ◽  
pp. 253
Author(s):  
L S Krivickas ◽  
D Suh ◽  
R Roubenoff ◽  
V A Hughes ◽  
W R Frontera
Keyword(s):  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Type I ◽  
Single Muscle ◽  
Sectional Area ◽  
Cross Sectional ◽  
Maximal Force

Absence of regional differences in the size and oxidative capacity of diaphragm muscle fibers

1987 ◽  
Vol 63 (3) ◽  
pp. 1076-1082 ◽  
Author(s):  
G. C. Sieck ◽  
R. D. Sacks ◽  
C. E. Blanco
Keyword(s):  
Muscle Fibers ◽  
Continuous Distribution ◽  
Oxidative Capacity ◽  
Cross Sectional Area ◽  
Diaphragm Muscle ◽  
Type I ◽  
Fiber Types ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fast Twitch

The oxidative capacity and cross-sectional area of muscle fibers were compared between the costal and crural regions of the cat diaphragm and across the abdominal-thoracic extent of the muscle. Succinate dehydrogenase (SDH) activity of individual fibers was quantified using a microphotometric procedure implemented on an image-processing system. In both costal and crural regions, population distributions of SDH activities were unimodal for both type I and II fibers. The continuous distribution of SDH activities for type II fibers indicated that no clear threshold exists for the subclassification of fibers based on differences in oxidative capacity (e.g., the classification of fast-twitch glycolytic and fast-twitch oxidative glycolytic fiber types). No differences in either SDH activity or cross-sectional area were noted between fiber populations of the costal and crural regions. Differences in SDH activity and cross-sectional area were noted, however, between fiber populations located on the abdominal and thoracic sides of the costal region. Both type I and II fibers on the abdominal side of the costal diaphragm were larger and more oxidative than comparable fibers on the thoracic side.

Myonuclear number and myosin heavy chain expression in rat soleus single muscle fibers after spaceflight

1996 ◽  
Vol 81 (1) ◽  
pp. 145-151 ◽  
Author(s):  
D. L. Allen ◽  
W. Yasui ◽  
T. Tanaka ◽  
Y. Ohira ◽  
S. Nagaoka ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Soleus Muscle ◽  
Heavy Chain ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Type I ◽  
Type Ii ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fiber Size

The effects of 14 days of spaceflight on myonuclear number, fiber size, and myosin heavy chain (MHC) expression in isolated rat soleus muscle fiber segments were studied. Single soleus muscle fibers from rats flown on the Spacelab Life Sciences-2 14-day mission were compared with those from age-matched ground-based control rats by using confocal microscopy and gel electrophoresis. Spaceflight resulted in a significant reduction in the number of fibers expressing type I MHC and an increase in the number of fibers expressing type IIx or IIa MHC. Space-flight also resulted in an increase in the percentage of fibers coexpressing more than one MHC and in the reexpression of the neonatal isoform of MHC in some fibers. Fiber cross-sectional area was significantly reduced in pure type I MHC-expressing fibers and in fibers coexpressing type I+II MHC but not in fibers expressing one or more type II MHC in the flight rats. The number of myonuclei per millimeter was significantly reduced in type I MHC-expressing fibers from the flight rats but was not significantly different in type I+II and type II MHC-coexpressing fibers. Fibers expressing neonatal MHC were similar in size to control fibers but had significantly fewer myonuclei per millimeter than flight fibers not expressing neonatal MHC. In type I MHC-expressing fibers, the reduction in fiber cross-sectional area was greater than the reduction in myonuclear number; thus the average cytoplasmic volume per myonucleus was significantly lower in flight than in control fibers. The reduction in both myonuclear number and fiber size of fibers expressing type I MHC after 14 days of spaceflight supports the hypothesis that changes in the number of myonuclei may be a contributing factor to the reduction in fiber size associated with chronic unloading of the musculature.

Fiber Type and Size as Sources of Variation in Human Single Muscle Fiber Passive Elasticity

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Alex M. Noonan ◽  
Derek P. Zwambag ◽  
Nicole Mazara ◽  
Erin Weersink ◽  
Geoffrey A. Power ◽  
...  
Keyword(s):  
Composite Materials ◽  
Muscle Fiber ◽  
Fiber Diameter ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Single Muscle ◽  
Sectional Area ◽  
Cross Sectional ◽  
Single Muscle Fiber

Abstract Studies on single muscle fiber passive material properties often report relatively large variation in elastic modulus (or normalized stiffness), and it is not clear where this variation arises. This study was designed to determine if the stiffness, normalized to both fiber cross-sectional area and length, is inherently different between types 1 and 2 muscle fibers. Vastus lateralis fibers (n = 93), from ten young men, were mechanically tested using a cumulative stretch-relaxation protocol. SDS-PAGE classified fibers as types 1 or 2. While there was a difference in normalized stiffness between fiber types (p = 0.0019), an unexpected inverse relationship was found between fiber diameter and normalized stiffness (r = −0.64; p < 0.001). As fiber type and diameter are not independent, a one-way analysis of covariance (ANCOVA) including fiber diameter as a covariate was run; this eliminated the effect of fiber type on normalized stiffness (p = 0.1935). To further explore the relationship between fiber size and elastic properties, we tested whether stiffness was linearly related to fiber cross-sectional area, as would be expected for a homogenous material. Passive stiffness was not linearly related to fiber area (p < 0.001), which can occur if single muscle fibers are better represented as composite materials. The rule of mixtures for composite materials was used to explore whether the presence of a stiff perimeter-based fiber component could explain the observed results. The model (R2 = 0.38) predicted a perimeter-based normalized stiffness of 8800 ± 2600 kPa/μm, which is within the range of basement membrane moduli reported in the literature.

Effect of Early Low-Intensity Exercise on Rat Hind-Limb Muscles Following Acute Ischemic Stroke

2006 ◽  
Vol 7 (3) ◽  
pp. 163-174 ◽  
Author(s):  
Myoung-Ae Choe ◽  
Gyeong Ju An ◽  
Yoon-Kyong Lee ◽  
Ji Hye Im ◽  
Smi Choi-Kwon ◽  
...  
Keyword(s):  
Hind Limb ◽  
Gastrocnemius Muscle ◽  
Exercise Group ◽  
Cross Sectional Area ◽  
Type I ◽  
Sectional Area ◽  
Muscle Type ◽  
Cross Sectional ◽  
Low Intensity ◽  
Low Intensity Exercise

This study examined the effects of daily low-intensity exercise following acute stroke on mass, Type I and II fiber cross-sectional area, and myofibrillar protein content of hind-limb muscles in a rat model. Adult male Sprague-Dawley rats were randomly assigned to 1 of 4 groups (n = 7-9 per group): stroke (occlusion of the right middle cerebral artery [RMCA]), control (sham RMCA procedure), exercise, and stroke-exercise. Beginning 48 hours post-stroke induction/sham operation, rats in the exercise group had 6 sessions of exercise in which they ran on a treadmill at grade 10 for 20 min/day at 10 m/min. At 8 days poststroke, all rats were anesthetized and soleus, plantaris, and gastrocnemius muscles were dissected from both the affected and unaffected sides. After 6 sessions of exercise following acute ischemic stroke, the stroke-exercise group showed the following significant (p < .05) increases compared to the stroke-only group: body weight and dietary intake, muscle weight of affected soleus and both affected and unaffected gastrocnemius muscle, Type I fiber cross-sectional area of affected soleus and both affected and unaffected gastrocnemius muscle, Type II fiber cross-sectional area of the unaffected soleus, both affected and unaffected plantaris and gastrocnemius muscle, Type II fiber distribution of affected gastrocnemius muscle, and myofibrillar protein content of both affected and unaffected soleus muscle. Daily low-intensity exercise following acute stroke attenuates hind-limb muscle atrophy in both affected and unaffected sides. The effects of exercise are more pronounced in the soleus and gastrocnemius as compared to the plantaris muscle.

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

1987 ◽  
Vol 57 (6) ◽  
pp. 1730-1745 ◽  
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.

Interactive effects of emphysema and malnutrition on diaphragm structure and function

1994 ◽  
Vol 77 (2) ◽  
pp. 947-955 ◽  
Author(s):  
M. I. Lewis ◽  
S. A. Monn ◽  
W. Z. Zhan ◽  
G. C. Sieck
Keyword(s):  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Cross Sectional Area ◽  
Interactive Effects ◽  
Type I ◽  
Specific Force ◽  
Type Ii ◽  
Sectional Area ◽  
Succinate Dehydrogenase Activity ◽  
Cross Sectional

Interactive effects of emphysema (EMP) and prolonged nutritional deprivation (ND) on contractile, morphometric, and metabolic properties of hamster diaphragm muscle (DIA) were examined. Six months after induction of EMP (intratracheal elastase), saline-treated controls (CTL) and EMP hamsters of similar body weights were subjected to ND over 6 wk. Isometric contractile and fatigue properties of costal DIA were determined in vitro. DIA fibers were histochemically classified as type I or II, and fiber succinate dehydrogenase activity and cross-sectional area were determined using quantitative microscopic procedures. From histochemical sections, the number of capillaries per fiber (C/F) and per fiber cross-sectional area (C/A) were determined. ND resulted in progressive loss of body weight (ND-CTL, 23.8%; ND-EMP, 28.4%; P = NS). ND did not affect reduction in optimal length (Lo) of DIA fibers in EMP compared with CTL and ND-CTL hamsters. Maximum specific force (i.e., force/unit area) was reduced by approximately 25% in EMP animals compared with CTL. ND did not improve or exacerbate the reduction in specific force with EMP. ND attenuated improved fatigue resistance of DIA in EMP animals. No differences in fiber type proportions were noted among experimental groups. Significant atrophy of type I and II DIA fibers was noted after ND. Atrophy was proportionately greater in type II fibers of ND-EMP when referenced to EMP animals. Thus adaptive hypertrophy of type II DIA fibers in EMP animals was abolished. Fiber succinate dehydrogenase activity was significantly increased in type I and II fibers in EMP DIA. ND did not affect this metabolic adaptation of DIA fibers to persistent loads imposed by EMP.(ABSTRACT TRUNCATED AT 250 WORDS)

Rat diaphragm during postnatal development. I. Changes in distribution of muscle fibre type and in oxidative potential

1996 ◽  
Vol 8 (3) ◽  
pp. 391 ◽  
Author(s):  
MD Fratacci ◽  
M Levame ◽  
A Rauss ◽  
H Bousbaa ◽  
G Atlan
Keyword(s):  
Muscle Fibre ◽  
Fibre Type ◽  
Oxidative Capacity ◽  
Cross Sectional Area ◽  
Fibre Types ◽  
Type I ◽  
Sectional Area ◽  
Rat Diaphragm ◽  
Oxidative Potential ◽  
Cross Sectional

The changes occurring in the histochemical characteristics of the rat diaphragm during the postnatal period were examined. Fibre-type distribution, fibre oxidative capacity, i.e. succinate-dehydrogenase (SDH) activity, and cross-sectional area were compared in the costal (COS) and crural (CRU) regions, and across their abdominal and thoracic surfaces. The proportions of type I and IIb fibres in both COS and CRU increased with age, while the proportion of type IIa fibres progressively decreased. For COS, fibre distribution was homogeneous over the entire muscle and did not change after 4 weeks. For CRU, it was heterogeneous with a higher proportion of type I fibres on the thoracic surface as from the first week. All fibre types significantly increased in cross-sectional area between 1 and 8 weeks, with no significant differences in COS and CRU. Mean SDH activity did not differ between COS and CRU or across the muscles. Mean SDH activities-were low and identical in all fibre types at birth, and then increased, peaking at the 6th week in type I and IIa fibres. When total muscle fibre oxidative capacity was calculated from an index including fibre-type proportion, cross-sectional area and mean SDH activity, it was significantly higher at 1 than at 8 weeks after birth; this might have functional implications for the newborn.

scholarly journals Soleus fiber force and maximal shortening velocity after non-weight bearing with intermittent activity

1996 ◽  
Vol 80 (3) ◽  
pp. 981-987 ◽  
Author(s):  
J. J. Widrick ◽  
J. J. Bangart ◽  
M. Karhanek ◽  
R. H. Fitts
Keyword(s):  
Isometric Force ◽  
Weight Bearing ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Cross Sectional Area ◽  
Type I ◽  
Sectional Area ◽  
Shortening Velocity ◽  
Adult Rats ◽  
Cross Sectional

This study examined the effectiveness of intermittent weight bearing (IWB) as a countermeasure to non-weight-bearing (NWB)-induced alterations in soleus type I fiber force (in mN), tension (Po; force per fiber cross-sectional area in kN/m-2), and maximal unloaded shortening velocity (Vo, in fiber lengths/s). Adult rats were assigned to one of the following groups: normal weight bearing (WB), 14 days of hindlimb NWB (NWB group), and 14 days of hindlimb NWB with IWB treatments (IWB group). The IWB treatment consisted of four 10-min periods of standing WB each day. Single, chemically permeabilized soleus fiber segments were mounted between a force transducer and position motor and were studied at maximal Ca2+ activation, after which type I fiber myosin heavy-chain composition was confirmed by sodium dodecyl sufate-polyacrylamide gel electrophoresis. NWB resulted in a loss in relative soleus mass (-45%), with type I fibers displaying reductions in diameter (-28%) and peak isometric force (-55%) and an increase in Vo (+33%). In addition, NWB induced a 16% reduction in type I fiber Po, a 41% reduction in type I fiber peak elastic modulus [Eo, defined as (delta force/delta length) x (fiber length/fiber cross-sectional area] and a significant increase in the Po/Eo ratio. In contrast to NWB, IWB reduced the loss of relative soleus mass (by 22%) and attenuated alterations in type I fiber diameter (by 36%), peak force (by 29%), and Vo (by 48%) but had no significant effect on Po, Eo, or Po/Eo. These results indicate that a modest restoration of WB activity during 14 days of NWB is sufficient to attenuate type I fiber atrophy and to partially restore type I peak isometric force and Vo to WB levels. However, the NWB-induced reductions in Po and Eo, which we hypothesize to be due to a decline in the number and stiffness of cross bridges, respectively, are considerably less responsive to this countermeasure treatment.

scholarly journals Morphological peculiarities of neuromuscular junctions among different fiber types: Effect of exercise

2017 ◽  
Vol 27 (3) ◽  
Author(s):  
Teet Seene ◽  
Maria Umnova ◽  
Priit Kaasik
Keyword(s):  
Axon Terminal ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Fiber Types ◽  
Sectional Area ◽  
Cross Sectional ◽  
Thin Sections ◽  
Axon Terminals ◽  
Ultrastructural Studies

The aim of our research was to examine whether there are differences in the morphology of neuromuscular junctions of different types of muscle fibers in rodents, and after their adaptation to six weeks endurance exercise training. After 5-day acclimation, Wistar rats were subjected to run with the speed 35 m/min during 6 week, 5 days per week and the training volume reached 60 min per day. Muscle samples for ultrastructural studies were fixed, dehydrated and embedded in Epon-812. Ultra-thin sections were cut from longitudinally and transversely oriented blocs, using 4 blocks from each animal. The area of axon terminals on fast- twitch fibers is 1.5 time large (p&lt;0.001) and the perimeter of terminals is 1.7 time large in comparison with slow- twitch oxidative fibers (p&lt;0.001) in control group. There are correlation between cross-sectional area of different muscle fibers and length of axon terminals (r=0.72), between cross-sectional area and with of axon terminal (r=-0.62), and between turnover rate of contractile proteins and length of axon terminal (r=0.75). Fast remodeling of synapse on oxidative and oxidative-glycolytic muscle fibers during endurance training seems to guarantees the intensive renewal of the structures of muscle fibers with higher oxidative capacity.

Contractile properties of rat, rhesus monkey, and human type I muscle fibers

1997 ◽  
Vol 272 (1) ◽  
pp. R34-R42 ◽  
Author(s):  
J. J. Widrick ◽  
J. G. Romatowski ◽  
M. Karhanek ◽  
R. H. Fitts
Keyword(s):  
Rhesus Monkey ◽  
Body Mass ◽  
Fiber Length ◽  
Peak Power ◽  
Cross Sectional Area ◽  
Contractile Properties ◽  
Type I ◽  
Sectional Area ◽  
Shortening Velocity ◽  
Cross Sectional

It is well known that skeletal muscle intrinsic maximal shortening velocity is inversely related to species body mass. However, there is uncertainty regarding the relationship between the contractile properties of muscle fibers obtained from commonly studied laboratory animals and those obtained from humans. In this study we determined the contractile properties of single chemically skinned fibers prepared from rat, rhesus monkey, and human soleus and gastrocnemius muscle samples under identical experimental conditions. All fibers used for analysis expressed type I myosin heavy chain as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Allometric coefficients for type I fibers from each muscle indicated that there was little change in peak tension (force/fiber cross-sectional area) across species. In contrast, both soleus and gastrocnemius type I fiber maximal unloaded shortening velocity (Vo), the y-intercept of the force-velocity relationship (Vmax), peak power per unit fiber length, and peak power normalized for fiber length and cross-sectional area were all inversely related to species body mass. The present allometric coefficients for soleus fiber Vo (-0.18) and Vmax (-0.11) are in good agreement with published values for soleus fibers obtained from common laboratory and domesticated mammals. Taken together, these observations suggest that the Vo of slow fibers from quadrupeds and humans scale similarly and can be described by the same quantitative relationships. These findings have implications in the design and interpretation of experiments, especially those that use small laboratory mammals as a model of human muscle function.

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