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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    European journal of applied physiology 70 (1995), S. 58-65 
    ISSN: 1439-6327
    Schlagwort(e): Oxygen uptake ; Lactate ; Wingate test ; Runners
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We investigated the aerobic and anaerobic contributions to performance during the Wingate test in sprint and middle-distance runners and whether they were related to the peak aerobic and anaerobic performances determined by two commonly used tests: the force-velocity test and an incremental aerobic exercise test. A group of 14 male competitive runners participated: 7 sprinters, aged 20.7 (SEM 1.3) years, competing in 50, 100 and 200-m events and 7 middle-distance runners, aged 20.0 (SEM 1.0) years, competing in 800, 1,000 and 1,500 m-events. The oxygen uptake ( $$\dot V{\text{O}}_{\text{2}} $$ ) was recorded breath-by-breath during the test (30 s) and during the first 20 s of recovery. Blood samples for venous plasma lactate concentrations were drawn at rest before the start of the test and during the 20-min recovery period. During the Wingate test mean power ( $$\dot W$$ ) was determined and three values of mechanical efficiency, one individual and two arbitrary, 16% and 25%, were used to calculate the contributions of work by aerobic ( $$\dot W$$ aer,ind,16%,25%) and anaerobic ( $$\dot W$$ an,ind,16%,25%) processes. Peak anaerobic power ( $$\dot W$$ an,peak) was estimated by the force-velocity test and maximal aerobic energy expenditure ( $$\dot W$$ aer,peak) was determined during an incremental aerobic exercise test. During the Wingate test, the middle-distance runners had a significantly greater $$\dot V{\text{O}}_{\text{2}} $$ than the sprinters (P 〈 0.001), who had significantly greater venous plasma lactate concentrations (P 〈 0.001). Moreover, $$\dot W$$ aer,ind,16%,25% were also significantly higher (P 〈 0.05) in the middle-distance runners [ $$\dot W$$ aer,ind 45 (SEM 4) % vs 28 (SEM 2) %; $$\dot W$$ aer,16% 30 (SEM 3) % vs 19 (SEM 2) %; $$\dot W$$ aer,25% 46 (SEM 3) % vs 29 (SEM 2)%]; $$\dot W$$ an,ind,16%,25% in the sprint runners (P 〈 0.05) [ $$\dot W$$ an,ind 72 (SEM 3) % vs 55 (SEM 4) %; $$\dot W$$ an,16% 81 (SEM 2) % vs 70 (SEM 3) %; $$\dot W$$ an,25% 71 (SEM 2) % vs 54 (SEM 3) %]. The $$\dot W$$ aer,ind/ $$\dot W$$ aer,peak and $$\dot W$$ × $$\dot W$$ an,ind/ $$\dot W$$ an,peak ratios, however, were not significantly different between the two groups of athletes. These results would indicate that the sprinters and middle-distance runners used preferentially a metabolic system according to their speciality. Nevertheless, under the conditions of its experiment, they seemed to rely on the same percentage of both peak anaerobic and peak aerobic performance for a given exercise task.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1439-6327
    Schlagwort(e): Arterio-venous difference ; Lactate ; Force-velocity test
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We investigated the role of the forearm skeletal muscles in the removal of lactate during repeated periods of short-term intensive leg exercise, i.e. a force-velocity (FV) test known to induce a marked accumulation of lactate in the blood. The leg FV test was performed by seven untrained male subjects. Arterial and venous blood samples for determination of arterial ([la−]a) and venous ([la−]v) plasma lactate concentrations were concomitantly taken at rest before the test, during the FV test at the end of each period of intensive exercise just before the 5-min between-sprint recovery period, and after the completion of the test at 2, 4, 6, 8, 10, 15, and 20 min of the final recovery. The arteriovenous difference in concentration for plasma lactate ([la−]a−v) was determined for each blood sample. During the test, [la−]a and [la−]v increased significantly (P 〈 0.001;P 〈 0.001) with significantly higher values for [la−]a (P 〈 0.001). At the onset of the test, [la−]a−v became positive and increased up to a braking force of 6 kg, correlating significantly with [la−]a (r = 0.61,P 〈 0.001) with power (r = 0.58,P 〈 0.001) during the test. At the end of the test, [la−]a, [la−]v and [la−]a−v decreased (P 〈 0.001;P 〈 0.001;P 〈 0.001 respectively) but were still higher than the basal values after 20-min of passive recovery. In conclusion, forearm skeletal muscles would seem to have been involved in the removal of lactate from the blood during the leg FV test, with an increase in lactate uptake proportional to the increase in plasma lactate concentration and power.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1439-6327
    Schlagwort(e): Key words Exercise ; 1H nuclear magnetic resonance ; 31P nuclear magnetic resonance ; Perfused muscle ; Lactate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We investigated whether localized 1H nuclear magnetic resonance spectroscopy (NMRS) using stimulated echoes (STEAM) with a long mixing time (t m) allowed the suppression of the fat signal and detection of lactate in skeletal muscle. The 1H NMRS sequence was first validated in three isolated and perfused rabbit biceps brachii muscles. Spectra were obtained on a wide-bore spectrometer using a dual-tuned probe (1H and 31P). Death was simulated by ceasing the muscle perfusion, which allowed post-mortem changes to be followed. During and after the simulated death, changes in levels of pH and in content of energy-rich compounds were observed with 31P NMRS. Our results showed an inverse linear relationship between pH and lactate in each of the three rabbits (r = 0.93, P 〈 0.001; r = 0.92, P 〈 0.01; r = 0.89, P 〈 0.01) and a decrease in phosphocreatine and concomitant increase in lactate. We then investigated whether this sequence allowed repeated detection of lactate in human soleus muscle during the recovery between periods of intense exercise (force-velocity test, F-v test). Seven subjects mean age 25.1 (SEM 0.8) years participated in this study. Soleus muscle lactate was detected at rest and for 3 min 30 s of the 5-min recovery between periods using a 2.35-T 40-cm bore magnet spectrometer. Arm venous plasma lactate concentration was measured at rest, during the F-v test when the subject stopped pedalling (S1), and at the end of each 5-min recovery between periods (S2). Results showed that the venous plasma lactate concentration at S1 and S2 increased significantly from the beginning of the F-v test to peak anaerobic power (W an,peak) (P 〈 0.001). The spectra showed that muscle lactate resonance intensity rose markedly when W an,peak was achieved. The muscle lactate resonance intensity plotted as a percentage of the resting value increased significantly at W an,peak compared with submaximal braking forces (P 〈 0.05). We concluded from these results that localized 1H NMRS using STEAM with a long t m allows suppression of the fat signal and repeated detection of lactate on isolated perfused skeletal muscle in animals and between periods of intense exercise in humans.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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