The Effects of Immobilization, after Lower Leg Fracture, on the Contractile Properties of Human Triceps Surae

1984 ◽  
Vol 66 (3) ◽  
pp. 277-282 ◽  
Author(s):  
M. J. White ◽  
C. T. M. Davies
Keyword(s):  
Lower Leg ◽  
Voluntary Contraction ◽  
Contractile Properties ◽  
Triceps Surae ◽  
Anthropometric Measurement ◽  
Muscle Fibres ◽  
Type I ◽  
Cross Sectional ◽  
Tension Development ◽  
Lower Leg Fracture

1. The contractile properties of the triceps surae were evaluated in 11 patients after unilateral fracture of the lower leg and subsequent immobilization for 135 ± 68 days. Calf muscle cross-sectional area (plus bone: CSA) was assessed from anthropometric measurement. 2. It was shown that the injured leg had a faster time to peak tension and increased half-relaxation time (1/2RT); twitch force (Pt) was reduced by 25%. Evoked maximal tetanic tensions (P0) at 10 and 20 Hz were reduced by 51% and 46% respectively compared with the uninjured leg. The force of a maximal voluntary contraction (MVC) was also reduced, by 50%, but calf circumference and CSA were only 5% and 16% respectively lower in the injured leg. 3. It was concluded that the changes in contractile speed may indicate a relatively greater atrophy of slow (type I) muscle fibres. 4. The relationship between CSA and tension generation in the injured limb was shown to be poor after immobilization and during recovery. Anthropometric estimation of CSA does not appear to reflect the degree of muscle wasting, as indicated by reduced tension development after immobilization.

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.

Changes in the human muscle force-velocity relationship in response to resistance training and subsequent detraining

2005 ◽  
Vol 99 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Lars L. Andersen ◽  
Jesper L. Andersen ◽  
S. Peter Magnusson ◽  
Charlotte Suetta ◽  
Jørgen L. Madsen ◽  
...  
Keyword(s):  
Resistance Training ◽  
Knee Extension ◽  
Limb Movement ◽  
Cross Sectional Area ◽  
Contractile Properties ◽  
Type I ◽  
Maximal Velocity ◽  
Sectional Area ◽  
Cross Sectional ◽  
Muscle Cross Sectional Area

Previous studies show that cessation of resistance training, commonly known as “detraining,” is associated with strength loss, decreased neural drive, and muscular atrophy. Detraining may also increase the expression of fast muscle myosin heavy chain (MHC) isoforms. The present study examined the effect of detraining subsequent to resistance training on contractile performance during slow-to-medium velocity isokinetic muscle contraction vs. performance of maximal velocity “unloaded” limb movement (i.e., no external loading of the limb). Maximal knee extensor strength was measured in an isokinetic dynamometer at 30 and 240°/s, and performance of maximal velocity limb movement was measured with a goniometer during maximal unloaded knee extension. Muscle cross-sectional area was determined with MRI. Electromyographic signals were measured in the quadriceps and hamstring muscles. Twitch contractions were evoked in the passive vastus lateralis muscle. MHC isoform composition was determined with SDS-PAGE. Isokinetic muscle strength increased 18% ( P < 0.01) and 10% ( P < 0.05) at slow and medium velocities, respectively, along with gains in muscle cross-sectional area and increased electromyogram in response to 3 mo of resistance training. After 3 mo of detraining these gains were lost, whereas in contrast maximal unloaded knee extension velocity and power increased 14% ( P < 0.05) and 44% ( P < 0.05), respectively. Additionally, faster muscle twitch contractile properties along with an increased and decreased amount of MHC type II and MHC type I isoforms, respectively, were observed. In conclusion, detraining subsequent to resistance training increases maximal unloaded movement speed and power in previously untrained subjects. A phenotypic shift toward faster muscle MHC isoforms (I → IIA → IIX) and faster electrically evoked muscle contractile properties in response to detraining may explain the present results.

Contractile adaptations in the human triceps surae after isometric exercise

1989 ◽  
Vol 66 (6) ◽  
pp. 2725-2732 ◽  
Author(s):  
S. E. Alway ◽  
J. D. MacDougall ◽  
D. G. Sale
Keyword(s):  
Volume Density ◽  
Voluntary Contraction ◽  
Triceps Surae ◽  
Type I ◽  
Type Ii ◽  
Contraction Time ◽  
Twitch Contraction ◽  
Human Triceps Surae ◽  
Before And After ◽  
Type Ii Fibers

Ultrastructural and twitch contractile characteristics of the human triceps surae were determined in seven healthy but very sedentary subjects before and after 16 wk of unilateral isometric training at 100% maximal voluntary contraction. After training, twitch contraction time decreased by approximately 20%. One-half relaxation time, peak twitch torque, and percent fiber type in any of the muscles of the triceps surae complex were not changed by training. Type I and type II fiber areas increased in the soleus by approximately 30%, but only type II fibers showed an increased in area in the lateral gastrocnemius (40%). Despite such changes in fiber area, the volume density of the sarcoplasmic reticulum-transverse tubular (SR) network averaged 3.2 +/- 0.6 and 5.9 +/- 0.9% in type I and type II fibers, respectively, before and after training in the two heads of the gastrocnemius. Type I SR fraction increased to 3.5 +/- 1.2% after training in the soleus; however, correlations were not significant between the change in the volume density of SR and the change in twitch contraction time (R = 0.46, P = 0.45) or the change in one-half relaxation time (R = -0.68, P = 0.08). The results demonstrate that isometric training at 100% maximal voluntary contraction induced changes in twitch contraction time that were not directly related to changes in the volume density of SR in fibers of the triceps surae.

Changes in Striated Muscle Fibres During Contraction and Growth with Particular Reference to Myofibril Splitting

1971 ◽  
Vol 9 (1) ◽  
pp. 123-137
Author(s):  
G. GOLDSPINK
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Actin Filaments ◽  
Sarcomere Length ◽  
Biceps Brachii ◽  
Hexagonal Lattice ◽  
Muscle Fibres ◽  
Cross Sectional ◽  
Tension Development ◽  
Transverse Tubular System ◽  
Myosin Filaments

Ultrastructural measurements were carried out on the mouse biceps brachii and soleus muscles fixed at different states of contraction and stretch. At a sarcomere length of 2.7-2.9 µm the more peripheral actin filaments ran slightly obliquely from the Z-disk to the A-band. This is due to a mismatch between the rhombic actin lattice at the Z-disk and the hexagonal lattice at the M-line. For a perfect transformation of a rhombic lattice into a hexagonal lattice the ratio of the lattice spacings has to be 1:1.51. However, at this sarcomere length the ratio is about 1:2.0 (Z:M). During contraction the angle of the peripheral actin filaments remains approximately the same because the expansion of the M lattice is compensated for, partly by an increase in the Z-lattice spacing and partly by the bowing of the peripheral myosin filaments. When the sarcomeres are stretched beyond 3.0 µm the myosin filaments straighten out and the Z:M ratio decreases. The ratio of 1:1.51 is almost attained when there is no overlap of the actin and myosin filaments. Ultrastructural measurements were also carried out on biceps brachii muscles of different ages. The lattice spacings for a standard sarcomere length did not change during the post-natal growth period. The amount of myofibrillar material and sarcoplasmic reticulum plus transverse tubular system were estimated using linear analysis for muscles at 3 different stages of growth. It was found that the myofibrillar cross-sectional area in an individual muscle fibre may increase 40-fold during growth and that the transverse tubular and sarcoplasmic reticulum systems increase at about the same rate. In both the biceps brachii and the soleus muscles the myosin and actin filaments are not built into a continuous mass but they are divided into numerous discrete myofibrils. Subdivision of the myofibril mass occurs because the myofibrils split once they attain a certain size. The evidence presented in this paper supports the suggestion that the longitudinal splitting of the myofibrils occurs by the ripping of the Z-disks. When tension is rapidly developed by 2 adjacent sarcomeres a stress is produced at the centre of the Z-disk resulting from the oblique pull of the actin filaments. This causes some of the Z-disk filaments to rip and the rip then extends across the disk with the direction of the weave of the lattice. Evidence for the mechanism includes electron-micrographs showing Z-disks that are apparently just commencing to split; in these cases a hole can be seen in the centre of the disk. A model experiment is described which demonstrates the importance of the rate of tension development in causing myofibril splitting. Rapid tension development produces a snatch effect which causes the Z-disk filaments to break more readily. This may explain why the myofibrils in fast muscles tend to be small and discrete whilst those in slow muscles are larger and more irregular in shape.

scholarly journals Contractile properties and sarcoplasmic reticulum calcium content in type I and type II skeletal muscle fibres in active aged humans

2015 ◽  
Vol 593 (11) ◽  
pp. 2499-2514 ◽  
Author(s):  
C. R. Lamboley ◽  
V. L. Wyckelsma ◽  
T. L. Dutka ◽  
M. J. McKenna ◽  
R. M. Murphy ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Calcium Content ◽  
Contractile Properties ◽  
Muscle Fibres ◽  
Type I ◽  
Type Ii ◽  
Skeletal Muscle Fibres ◽  
Sarcoplasmic Reticulum Calcium

Short-term immobilization and recovery affect skeletal muscle but not collagen tissue turnover in humans

2008 ◽  
Vol 105 (6) ◽  
pp. 1845-1851 ◽  
Author(s):  
Britt Christensen ◽  
Eva Dyrberg ◽  
Per Aagaard ◽  
Michael Kjaer ◽  
Henning Langberg
Keyword(s):  
Collagen Synthesis ◽  
Type I Collagen ◽  
Recovery Period ◽  
Triceps Surae ◽  
Muscle Size ◽  
Type I ◽  
Short Term ◽  
Cross Sectional ◽  
Significant Difference ◽  
Triceps Surae Muscles

Not much is known about the effects of immobilization and subsequent recovery on tendon connective tissue. In the present study, healthy young men had their nondominant leg immobilized for a 2-wk period, followed by a recovery period of the same length. Immobilization resulted in a mean decrease of 6% (5,413 to 5,077 mm2) in cross-sectional area (CSA) of the triceps surae muscles and a mean decrease of 9% (261 to 238 N·m) in strength of the immobilized calf muscles. Two weeks of recovery resulted in a 6% increased in CSA (to 5,367 mm2), whereas strength remained suppressed (240 N·m). No difference in Achilles tendon CSA was detected between the two legs at any time point. Local tendon collagen synthesis, measured as the peritendinous concentrations of PINP (NH2-terminal propeptide of type I collagen; indirect marker for collagen synthesis), was unchanged after 2 wk of immobilization. However, peritendinous levels of PINP were significantly elevated in the immobilized leg (15 to 139 ng/ml) following 2 wk of remobilization compared with preimmobilization levels. In contradiction hereto, systemic concentrations of PINP remained unchanged throughout the study. Immobilization reduced muscle size and strength, while tendon size and collagen turnover were unchanged. While recovery resulted in an increase in muscle size, strength was unchanged. No significant difference in tendon size could be detected between the two legs after 2 wk of recovery, although collagen synthesis was increased in the previously immobilized leg. Thus 2 wk of immobilization are sufficient to induce significant changes in muscle tissue, whereas tendon tissue seems to be more resistant to short-term immobilization.

Muscle fiber regeneration in nerve-intact and free skeletal muscle autografts in cats

1984 ◽  
Vol 246 (1) ◽  
pp. C96-C105 ◽  
Author(s):  
L. C. Maxwell
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Extensor Digitorum Longus ◽  
Contractile Properties ◽  
Type I ◽  
Tension Development ◽  
Fiber Area ◽  
Adult Cats ◽  
Type I Fibers ◽  
Muscle Fiber Regeneration

Extensor digitorum longus (EDL) muscles of adult cats were transplanted as free autografts (FRA) with the nerve severed or as nerve-intact autografts (NIA) with the nerve retained. Histochemical and contractile properties of NIA and FRA were analyzed at selected times from 1 to 14 wk after surgery. Regeneration was qualitatively similar in NIA and FRA. Regenerating fibers were observed in both NIA and FRA within 2 wk. After 14 wk there were fewer type I fibers in both NIA and FRA than in control EDL muscles. Capillarity was greater in NIA than FRA, but both types of autografts had significantly reduced capillarity relative to control muscles. Mean fiber area, muscle mass, and absolute tension development were greater in NIA than FRA but did not reach control muscle values. Muscle mass, mean fiber area, and contractile properties, but not the proportion of type I fibers, develop toward control values more quickly in autografts with the nerve left intact.

Strength and Contractile Adaptations in the Human Triceps Surae after Isotonic Exercise

1993 ◽  
Vol 2 (2) ◽  
pp. 104-114 ◽  
Author(s):  
Crayton L. Moss ◽  
Scott Grimmer
Keyword(s):  
Relaxation Time ◽  
Repeated Measures ◽  
Peak Force ◽  
Contractile Properties ◽  
Triceps Surae ◽  
Type I ◽  
Muscle Twitch ◽  
Time To Peak ◽  
High Repetition ◽  
Isotonic Exercise

The purpose of this study was to determine whether twitch contractile properties and strength of the triceps surae could be altered by 8 weeks of low-repetition or high-repetition isotonic exercise. Subjects were randomly assigned to either the low- or high-repetition group. Before- and after-training measurements were recorded for strength and contractile properties. The contractile variables of the muscle twitch were latency, time to peak force, peak force, half-contraction time, and half-relaxation time. Strength measurements were determined utilizing a one repetition maximal (1-RM) heel-raise testing device. A two-way ANOVA with repeated measures was used to test the effect of training on each variable. Both groups showed a significant increase in 1-RM and half-relaxation time and a decrease in electrical stimulation current after the 8-week training period. It was concluded that if high-repetition exercises develop slow-twitch Type I muscle fibers and low-repetition exercises develop fast-twitch Type II fibers, training programs must be designed specifically according to the desired outcome.

Architecture, composition, and contractile properties of rat soleus muscle grafts

1986 ◽  
Vol 250 (3) ◽  
pp. C474-C479 ◽  
Author(s):  
S. S. Segal ◽  
T. P. White ◽  
J. A. Faulkner
Keyword(s):  
Soleus Muscle ◽  
Muscle Length ◽  
Contractile Properties ◽  
Shortening Velocity ◽  
Cross Sectional ◽  
Tension Development ◽  
Specific Tension ◽  
Control Value ◽  
Rat Soleus Muscle ◽  
Total Muscle

Skeletal muscle grafts have a deficit in tension development compared with control muscles, even after accounting for reduced mass and total muscle cross-sectional area. Our purpose was to determine relationships among the architecture, tissue composition, and contractile properties of rat soleus muscle grafts. Data were compared with control soleus muscles obtained from littermates. Female Wistar rats were anesthetized with pentobarbital sodium for grafting of soleus muscles with nerve implant and for dissection of muscles 56 days after grafting. Compared with control values, the maximum specific tension (N/cm2) of grafts was 76%, the interstitial (inulin) space was 135%, and the connective tissue protein concentration was 177%. For grafts, total muscle length and fiber length were 91 and 123% of control values, respectively. The extrapolated shortening velocity at zero load (fiber lengths/s) for grafts was not different from the control value. The deficit in specific tension of grafts is explained by a greater concentration of noncontractile tissue components. Changes in muscle architecture and composition following grafting had little affect on contraction dynamics.

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