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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 52 (1984), S. 266-271 
    ISSN: 1439-6327
    Keywords: Human ; Endurance exercise ; Muscles ; Fibre types ; Histocytochemistry ; Ultrastructure ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The main fibre types ofM. vastus lateralis of 10 trained or untrained male individuals (25–35 years) were quantitatively determined by morphological techniques; the fibre types being defined according to the M-band appearance. The volume density of mitochondria (Vmit) was higher in endurance-trained muscles.Vmit was higher in Type 1 than in Type 2 fibres, there being no difference between subtypes of Type 2 fibres. The volume density of lipid droplets (Vli) showed a wide range of values both with respect to degree of training and between fibre types. Z-band width was not influenced by endurance training, but was considerably larger in Type 1 than in Type 2 fibres. Discriminant analysis showed that 46% of the fibres, preclassified according to the M-band appearance, would have been correctly allocated on basis of theVmit. The corresponding value for lipid droplets was 42% and for the Z-band width, 62%. It is concluded thatVmit is not a satisfactory criterion for discriminating between fibre types, especially between Type 2A and Type 2B in trained subjects. The study also shows that endurance training reduces the relative importance of individual-dependent factors in comparison with muscle fibre properties when concerningVmit.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 55 (1986), S. 74-78 
    ISSN: 1439-6327
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of the present study was to examine to what degree a reduction in systemic oxygen transport capacity influences the absolute and relative levels (% of maximal oxygen uptake) of submaximal blood lactate accumulation. Anemia was induced by repeated venesections in eight healthy males. After 9–10 weeks of anemia, hemoglobin concentration [Hb] was restored by retransfusion of packed erythrocytes. The [Hb] values obtained were, before venesections, in control (C)=145±10, in the anemic state (A)=110±8, and after retransfusion (R)=143+-8 g · l−1 respectively. In all states, muscle biopsies were taken and measurements made of $$V_{O_{2{\text{max}}} } $$ and $$V_{{\text{O}}_{\text{2}} }$$ at a running velocity corresponding to a blood lactate concentration of 4 mM (v Hla 4.0). In the A condition $$V_{O_{2{\text{max}}} } $$ decreased by 19% as compared to C (P〈0.01). v Hla 4.0. v Hla 4.0 was 14% lower in A as compared to C and R (p〈0.01). $$V_{{\text{O}}_{\text{2}} }$$ at v Hla 4.0 was 13% lower in A as compared to C (P〈0.01). However, $$V_{{\text{O}}_{\text{2}} }$$ at v Hla 4.0 expressed as a percentage of $$V_{O_{2{\text{max}}} } $$ was increased (P〈0.01) in the anemic state, the values obtained being C=83.3%, A=89.8% and R=84.8%. Ventilation at v Hla 4.0 was higher in A as compared to C and R (P〈0.05). R and C values were not significantly different for any of the values presented above. The maximal activity of citrate synthase in muscle did not differ between the three different conditions. It is concluded that a reduction in systemic oxygen transport leads to an absolute decrease in the fixed anaerobic threshold. However, peripheral factors modified this decrease. As a consequence there was a marked shift to the right, relative to $$V_{O_{2{\text{max}}} } $$ , in the submaximal lactate accumulation upon induction of anemia.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1439-6327
    Keywords: Acceleration ; Eccentric ; Concentric ; Isokinetic ; Method error
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new computerized dynamometer (the SPARK System) is described. The system can measure concentric and eccentric muscle strength (torque) during linear or nonlinear acceleration or deceleration, isokinetic movements up to 400° · s−1, and isometric torque. Studies were performed to assess: I. validity and reproducibility of torque measurements; II. control of lever arm position; III. control of different velocity patterns; IV. control of velocity during subject testing; and, V. intra-individual reproducibility. No significant difference was found between torque values computed by the system and known torque values (p〉0.05). No difference was present between programmed and external measurement of the lever arm position. Accelerating, decelerating and isokinetic velocity patterns were highly reproducible, with differences in elapsed time among 10 trials being never greater than 0.001 s. Velocity during concentric and eccentric isokinetic quadriceps contractions at 30° · s−1, 120° · s−1 and 270° · s−1 never varied by more than 3° · s−1 among subjects (N=21). Over three days of testing, the overall error for concentric and eccentric quadriceps contraction peak torque values for 5 angular velocities between 30° · s−1 and 270° · s−1 ranged from 5.8% to 9.0% and 5.8% to 9.6% respectively (N=25). The results indicate that the SPARK System provides valid and reproducible torque measurements and strict control of velocity. In addition, the intra-individual error is in accordance with those reported for other similar devices.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 58 (1988), S. 100-104 
    ISSN: 1439-6327
    Keywords: Man ; Torque-velocity characteristics ; Eccentric ; Concentric ; Quadriceps femoris ; Method error
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The primary purpose of this investigation was to study the eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man using a recently developed combined isometric, concentric and eccentric controlled velocity dynamometer (the SPARK System). A secondary purpose was to compare the method error associated with maximal voluntary concentric and eccentric torque output over a range of testing velocities. 21 males (21–32 years) performed on two separate days maximal voluntary isometric, concentric and eccentric contractions of the quadriceps femoris at 4 isokinetic lever arm velocities of 0° · s−1 (isometric), 30° · s−1 120° · s−1 and 270° · s−1. Eccentric peak torque and angle-specific torques (measured every 10° from 30° to 70°) did not significantly change from 0° · s−1 to 270° · s−1 (p〉0.05) (with the exception of angle-specific 40° torque, which significantly increased;p〈0.05). The mean method error was significantly higher for the eccentric tests (10.6%±1.6%) than for the concentric tests (8.1%±1.7%) (p〈0.05). The mean method error decreased slightly with increasing concentric velocity (p〉0.05), and increased slightly with increasing eccentric velocity (p〉0.05). A tension restricting neural mechanism, if active during maximal eccentric contractions, could possibly account for the large difference seen between the present eccentric torque-velocity results and the classic results obtained from isolated animal muscle.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 57 (1988), S. 360-368 
    ISSN: 1439-6327
    Keywords: Humans ; Skeletal muscles ; Anaerobic exercise ; Histocytochemistry ; Ultrastructure ; Muscle cell injury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The vastus lateralis muscles of eleven male elite sprinters (17–28 years) were investigated in order to examine the impact of high tension anaerobic muscular work on muscle fibre fine structure. In an attempt to reproduce the training regimen six subjects ran 20 repetitions of 25 s on a treadmill with 2 min 35 s in between, at a speed corresponding to 86% of their personal best 200 m time. PAS-stained sections of biopsies taken approximately 2 h after training generally indicated glycogen depletion in type 1 and type 2B fibres. At the light microscopic level, no signs of inflammation or fibre rupture were observed. However, at the ultrastructural level, frequent abnormalities of the contractile material and the cytoplasmic organelles were detected. Z-band streaming, autophagic vacuoles and abnormal mitochondria were the most conspicuous observations. Control specimens from sprinters who did not perform the acute exercise routine also displayed structural deviations, although to a lesser degree. It is hypothesized that during sprint training the leg musculature is put under great mechanical and metabolic stress which causes the degenerative response reported here.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Skeletal muscles ; Ultrastructure ; Exercise ; Glycogen ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these “depleted” type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed.
    Type of Medium: Electronic Resource
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