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  • 1980-1984  (2)
  • 1930-1934
  • Electrical stimulation  (2)
  • 1
    ISSN: 1439-6327
    Keywords: Exercise ; Triceps surae ; Anaerobic power output ; Force platform and bicycle ; Electrical stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The dynamic performance and electrically evoked mechanical properties of elderly triceps surae muscle have been investigated in 9 men, aged 69 yr. Dynamic performance consisted of cycling on a force bicycle and a vertical jump off two feet from a force platform. The results showed that the time to peak tension (TPT) and half relaxation time (1/2 RT) were significantly greater (p〈0.001) by 30 ms and 22 ms and the supramaximal twitch (Pt) and tetanic (20 H−P020) tensions and maximal voluntary contraction (MVC) were less by 45 N (−33%), 708 N (−49%), and 899 N (−43%) in the elderly compared with young male control subjects. On the force platform, the height jumped (Ht), maximal force exerted (P), take-off velocity (VT), net impulse (NI) and peak power output ( $$\dot W$$ ) were less by 18.6 cm, 173 N, 0.9 ms−1, 52 Ns and 1120 w respectively. Similar differences of power, force and velocity were observed on the force bicycle. The reduction of $$\dot W$$ in the elderly was associated with the contractile characteristics of the leg muscle. The loss of contractile speed and capacity to generate force in old people was reflected in their inability to develop power during the performance of a maximal vertical jump and cycling.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 52 (1983), S. 111-114 
    ISSN: 1439-6327
    Keywords: Muscle ; Children ; Electrical stimulation ; Strength ; Fatigue ; Sex differences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrically evoked mechanical and contractile properties of the triceps surae have been measured in 52 children aged 11 and 14 years, and results compared with previously reported data for adults (Davies and White 1982). The results show that the time to peak tension (TPT), half relaxation time (1/2RT) and supramaximal tension (Pt) of the twitch were not significantly (p〉0.1) different in girls and boys and independent of age. The 14-year-old girls and boys were stronger in terms of their supramaximal 10, 20, and 50 Hz tetanic tensions and maximal voluntary contraction (MVC) than their younger counterparts, and both groups of children were significantly (p〈0.001) weaker than the young adults. However, if standardisation was made for an anthropometric estimate of calf muscle (plus bone) cross-sectional area (CSA), the differences in strength disappeared. Electrically stimulated and voluntary maximal force per unit CSA measured at the knee were 17.1 and 20.5 N·cm2 respectively and independent of sex and age. The loss of force during a 2-min stimulated fatigue test was the same in the children as the adults. The average fatigue indices ranged from 0.52 to 0.72 in the children, compared with 0.68 in the adults. It is concluded that absolute differences in muscle strength in children are a function of muscle mass. The force generating capacity expressed in N·cm2, fatiguability, contraction and relaxation times of the triceps surae would appear to remain unchanged through adolescence and early adulthood.
    Type of Medium: Electronic Resource
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