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  • 1
    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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  • 2
    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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