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  • 1
    Electronic Resource
    Electronic Resource
    The effects of two forms of isometric training on the mechanical properties of the triceps surae in man (1985)
    Springer
    Pflügers Archiv 405 (1985), S. 384-388 
    Details
    ISSN: 1432-2013
    Keywords: Electrical stimulation ; Muscle ; Exercise ; Training ; Fatigue ; Isometric ; Endurance ; Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The training effects of rhythmic and sustained isometric contractions on the contractile characteristics of the triceps surae have been investigated in four healthy subjects over a period of 8 weeks. One leg (ST) of each subject was trained by performing repeated daily sustained (1 min) isometric contractions at 30% of maximal voluntary contraction force (MVC), and the other using rhythmic isometric contractions at 100% of MVC. The protocol was so arranged that the total area under the training force/ time curves was the same for each limb. Electrically evoked maximal twitch (P t) and tetanic (P o) tensions of the triceps surae were measured weekly on both legs using a standard procedure. The results showed that the rhythmic regime increased the MVC at the rate of 5.5% per week and the sustained training increased MVC at the rate of 3.3% per week. Twitch and tetanic tensions were not altered by either regime. However, only training using sustained contractions produced a progressive increase in endurance as measured by performance in a fatigue test. The results suggest that increases in voluntary strength resulting from short term isometric training are not necessarily associated with a rise in the intrinsic involuntary capacity of muscle fibres to generate force.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00595692
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of diet on human muscle weakness following prolonged exercise (1984)
    Springer
    European journal of applied physiology 53 (1984), S. 81-85 
    Details
    ISSN: 1439-6327
    Keywords: Work ; Fatigue ; Muscle glycogen ; Electrically stimulated contractions ; Strength ; Twitch and tetanic tensions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of altering muscle glycogen on the ability of skeletal muscle to generate voluntary and electrically evoked isometric force following prolonged exercise has been investigated in five healthy male subjects. Measurements from the triceps surae were made at rest, and before and after prolonged exercise (uphill walking) at approximately 75% $$\dot V_{{\text{O}}_{\text{2}} {\text{ max}}}$$ in low muscle glycogen (low CHO) and high muscle glycogen (high CHO) conditions. The results showed that before exercise there was no change in maximal twitch tension ( $${\text{P}}_{{\text{t}}_{\text{o}} }$$ ), maximal tetanic tension at frequencies of 10 (Po10), 20 (Po20) and 50 Hz (Po50), and maximal voluntary contraction (MVC) in low and high CHO compared with normal. The loss of force during a 2 min electrically evoked “fatigue test” at rest was found to be higher (p〈0.05) in low CHO and lower (p〈0.05) in high CHO than normal. Following the prolonged exercise, muscle weakness was produced in both low and high CHO conditions, but was found to be significantly greater in the low CHO condition for the measurements of Po10 (p〈0.01), Po20 (p〈0.05) and MVC (p〈0.05). It is concluded that changes in muscle glycogen alone do not alter the isometric force generating capacity of human muscle, but when combined with prolonged exercise low muscle glycogen enhances exercise-induced muscle weakness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964695
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Muscle function in children (1983)
    Springer
    European journal of applied physiology 52 (1983), S. 111-114 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00429036
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Electrically evoked isometric and isokinetic properties of the triceps surae in young male subjects (1988)
    Springer
    European journal of applied physiology 58 (1988), S. 321-326 
    Details
    ISSN: 1439-6327
    Keywords: Muscle ; Isometric ; Isokinetic ; Exercise ; Fatigue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between electrically evoked isometric and isokinetic properties of the triceps surae have been studied in 11 healthy male subjects. The results showed that the time to peak tension (TPT) and half relaxation time (1/2 RT) of the maximal twitch were 110±11 ms and 82±11 ms respectively, and the peak rates of rise of contraction (ΔP 50, ΔP 200) and relaxation (ΔP R50, ΔP R200) at 50 and 200 Hz were 0.36±0.07, 0.48±0.08 and 1.27±0.33, 1.25±0.27% Po ms−1 respectively. The decline in force during a fatigue test was significantly (P〈0.02) associated with the decrease in maximal relaxation rate (r=0.79). The TPT was significantly (P〈0.05) and inversely related to ΔP 50 and ΔP 200. The mean angle specific torque-velocity relationship for the 11 subjects was adequately described by the empirical exponential equation of the form: V=16.5 (e −p/30.8−e −84.3/30.8) where V=velocity (rads s−1) P=torque (Nm). The only significant association found between the isometric and isokinetic properties of the muscle was between ΔP R200 and the torque expressed at a given velocity of 4 rads s−1. This lack of association between the two variables is difficult to explain with certainty but it is suggested that it may be due to the differential effects of Ca2+ release and uptake and cross-bridge turnover rate in the two situations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00417270
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    Paper (German National Licenses)
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