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  • Competitive swimming  (2)
  • Maximal contraction  (2)
  • Electro-mechanical changes  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Hypoxia-induced fibre type transformation in rat hindlimb muscles (1990)
    Springer
    European journal of applied physiology 60 (1990), S. 331-336 
    Details
    ISSN: 1439-6327
    Keywords: Hypobaric hypoxia ; Muscle fibre type ; Histochemical changes ; Electro-mechanical changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twelve male Sprague-Dawley rats (21 days old) were randomly assigned into two experimental groups: sea level control (CONT) and hypobaric hypoxia (HYPO). The HYPO rats were kept in an hypobaric chamber maintaining a simulated altitude of 4000 m (61.1 kPa). After 10 weeks of treatment, the rat hindlimb muscles [soleus (SOL) and extensor digitorum longus (EDL)] were subjected to histochemical and electro-mechanical analyses. Results indicated that compared to CONT the HYPO SOL muscle had a significantly greater relative distribution of fast-twitch-oxidative-glycolytic (FOG) fibres (28.9% SEM 2.0 vs 18.3% SEM 1.8,P〈0.01) with a significant decrease in slow twitch oxidative fibre distribution (69.5% SEM 2.4 vs 82.9% SEM 3.1,P〈0.01). Compared to CONT the HYPO EDL muscle also manifested a significant increase in FOG fibre distribution (51.6% SEM 0.8 vs 46.6% SEM 1.1,P〈0.01), but this was accompanied by a significant decrease in fast twitch glucolytic fibres (44.3% SEM 0.9 vs 49.2% SEM 1.7,P〈0.05). These histochemical fibre type transformations accompanied significant and expected changes in the electro-mechanical parameters tested in situ, e.g. maximal twitch force, maximal rate of force development, contraction time, half relaxation time, force:frequency curve, and fatigability. It was concluded that chronic hypobaric hypoxia could have a potent influence upon the phenotype expression of muscle fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713495
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Movement-related cortical potentials during handgrip contractions with special reference to force and electromyogram bilateral deficit (1995)
    Springer
    European journal of applied physiology 72 (1995), S. 1-5 
    Details
    ISSN: 1439-6327
    Keywords: Movement-related cortical potentials ; Maximal contraction ; Bilateral deficit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated movement-related cortical potentials from motor cortex areas (C3 and C4) and isometric force and electromyogram (EMG) activity in association with maximal bilateral (BL) and unilateral (UL) handgrip contraction in eight right-handed subjects. The BL grip exhibited deficits in force [right, −5.2 (SEM 1.1)%; left, −4.5 (SEM 1.9)%] and EMG [right, −9.5 (SEM 2.2)%; left, −7.6 (SEM 2.5)%] compared with the UL grip. In the UL contractions, the amplitudes of the negative slope [NS′ 2.77 (SEM 0.70) vs 2.40 (SEM 0.76) μV·s for left hand,P 〈 0.05; 2.54 (SEM 0.55) vs 2.23(SEM 0.54) μV·s for right hand,P 〈 0.05 and motor potentials [MP: 1.56 (SEM 0.32) μV.s vs 1.23 (SEM 0.35) μV·s for left hand,P 〈 0.01; 1.44 (SEM 0.32) μV·s vs 1.10 (SEM 0.25) μV·s for right hand,P 〈 0.01] were greater in the contralateral hemisphere. For the BL contractions, the asymmetry of the larger potentials for the contralateral side disappeared and lower symmetrical potentials [NS′, 2.43 (SEM 0.61) μV·s for C3 vs 2.43 (SEM 0.63) μV·s for C4: MP: 1.31 (SEM 0.35) μV·s for C3 vs 1.34 (SEM 0.32) μV·s for C4] were observed. It was concluded that the BL deficit in force and EMG is associated with reduced movement-related cortical potentials suggesting that the bilateral force and (EMG) deficit compared with unilateral hand-grip contractions is caused by a mechanism of interhemispheric inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964106
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Maximal isometric force and neural activity during bilateral and unilateral elbow flexion in humans (1994)
    Springer
    European journal of applied physiology 69 (1994), S. 240-243 
    Details
    ISSN: 1439-6327
    Keywords: Human muscle ; Maximal contraction ; Electromyographic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated maximal isometric force and electromyographic (EMG) activity of the biceps brachii muscle during rapid bilateral (BL) and unilateral (UL) elbow flexion in 11 right-handed subjects. The BL exhibited a deficit in force for both arms and more so for the right than the left arm during the rising phase of force generation. The EMG of the left biceps brachii muscle was similar during UL and BL, but for the right arm EMG was lower during BL than during UL for the rising phase of force generation. The BL to UL ratio of mean power frequency of the EMG was lower for the right than for the left arm. The data would suggest that the relatively small BL strength was associated with a equally small EMG and a shift to a lower mean power frequency especially for the fast motor units of the dominant muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01094795
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Does critical swimming velocity represent exercise intensity at maximal lactate steady state? (1993)
    Springer
    European journal of applied physiology 66 (1993), S. 90-95 
    Details
    ISSN: 1439-6327
    Keywords: Competitive swimming ; Critical swimming velocity ; Maximal lactate steady state ; Onset of blood lactate accumulation ; Maximal oxygen uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this investigation was to determine whether the critical swimming velocity (ν crit), which is employed in competitive swimming, corresponds to the exercise intensity at maximal lactate steady state.ν crit is defined as the swimming velocity which could theoretically be maintained forever without exhaustion and expression as the slope of a regression line between swimming distances covered and the corresponding times. A total of eight swimmers were instructed to swim two different distances (200 m and 400 m) at maximal effort and the time taken to swim each distance was measured. In the present study,ν crit is calculated as the slope of the line connecting the two times required to swim 200 m and 400 m. vcrit determined by this new simple method was correlated significantly with swimming velocity at 4 mmol · 1−1 of blood lactate concentration (r = 0.914,P 〈 0.01) and mean velocity in the 400m freestyle (r = 0.977,P 〈 0.01). In the maximal lactate steady-state test, the subjects were instructed to swim 1600 m (4 x 400 m) freestyle at three constant velocities (98010, 100% and 102070 ofν crit). At 100%ν crit blood lactate concentration showed a steady-state level of approximately 3.2 mmol · 1− from the first to the third stage and at 98% ofν crit lactate concentration had a tendency to decrease significantly at the fourth stage. On the other hand, at 102% ofν crit, blood lactate concentration increased progressively and those of the third and fourth stages were significantly higher than those at 100% ofν crit (P〈0.05). These data suggest thatν crit, which can be calculated by performing two timed, maximal effort swimming tests, may correspond to the exercise intensity at maximal lactate steady state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00863406
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  • 5
    Electronic Resource
    Electronic Resource
    Determination and validity of critical velocity as an index of swimming performance in the competitive swimmer (1992)
    Springer
    European journal of applied physiology 64 (1992), S. 153-157 
    Details
    ISSN: 1439-6327
    Keywords: Competitive swimming ; Critical swimming velocity ; Onset of blood lactate accumulation ; Maximal oxygen consumption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this investigation was to test whether the concept of critical power used in previous studies could be applied to the field of competitive swimming as critical swimming velocity (νcrit). The νcrit, defined as the swimming velocity over a very long period of time without exhaustion, was expressed as the slope of a straight line between swimming distance (d lim) at each speed (with six predetermined speeds) and the duration (t lim). Nine trained college swimmers underwent tests in a swimming flume to measure νcrit at those velocities until the onset of fatigue. A regression analysis ofd lim on trim calculated for each swimmer showed linear relationships (r 2〉0.998,P〈0.01), and the slope coefficient signifying νcrit ranged from 1.062 to 1.262 m · s−1 with a mean of 1.166 (SD 0.052) m · s−1. Maximal oxygen consumption ( $$\dot VO_{2\max } $$ ), oxygen consumption ( $$\dot VO_2 $$ ) at anaerobic threshold, and the swimming also velocity at the onset of blood lactate accumulation (νOBLA) were also determined during the incremental swimming test. The νcrit showed significant positive correlations with $$\dot VO_2 $$ at anaerobic threshold (r=0.818,P〈0.01), νOBLA (r=0.949,P〈0.01) and mean velocity of 400m freestyle (r=0.864,P〈0.01). These data suggested that νcrit could be adopted as an index of endurance performance in competitive swimmers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00717953
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