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  • Human  (1)
  • Quadriceps femoris  (1)
  • 1
    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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  • 2
    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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