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  • 1
    Electronic Resource
    Electronic Resource
    Short-term exercise training improves diaphragm antioxidant capacity and endurance (2000)
    Springer
    European journal of applied physiology 81 (2000), S. 67-74 
    Details
    ISSN: 1439-6327
    Keywords: Key words Diaphragm ; Oxidative stress ; Fatigue ; Lipid peroxidation ; Antioxidants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract These experiments tested the hypothesis that short-term endurance exercise training would rapidly improve (within 5 days) the diaphragm oxidative/antioxidant capacity and protect the diaphragm against contraction-induced oxidative stress. To test this postulate, male Sprague-Dawley rats (6 weeks old) ran on a motorized treadmill for 5 consecutive days (40–60 min · day−1) at approximately 65% maximal oxygen uptake. Costal diaphragm strips were excised from both sedentary control (CON, n=14) and trained (TR, n=13) animals 24 h after the last exercise session, for measurement of in vitro contraction properties and selected biochemical parameters of oxidative/antioxidant capacity. Training did not alter diaphragm force-frequency characteristics over a full range of submaximal and maximal stimulation frequencies (P 〉 0.05). In contrast, training improved diaphragm resistance to fatigue as contraction forces were better-maintained by the diaphragms of the TR animals during a submaximal 60-min fatigue protocol (P 〈 0.05). Following the fatigue protocol, diaphragm strips from the TR animals contained 30% lower concentrations of lipid hydroperoxides compared to CON (P 〈 0.05). Biochemical analysis revealed that exercise training increased diaphragm oxidative and antioxidant capacity (citrate synthase activity +18%, catalase activity +24%, total superoxide dismutase activity +20%, glutathione concentration +10%) (P 〈 0.05). These data indicate that short-term exercise training can rapidly elevate oxidative capacity as well as enzymatic and non-enzymatic antioxidant defenses in the diaphragm. Furthermore, this up-regulation in antioxidant defenses would be accompanied by a reduction in contraction-induced lipid peroxidation and an increased fatigue resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013799
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Oxygen uptake kinetics in trained athletes differing in $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ (1985)
    Springer
    European journal of applied physiology 54 (1985), S. 306-308 
    Details
    ISSN: 1439-6327
    Keywords: Oxygen uptake kinetics ; $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ ; Exercise metabolism ; Trained athletes ; Gas exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous work has shown that when $$\dot V_{{\text{O}}_{\text{2}} }$$ kinetics are compared for endurance trained athletes and untrained subjects, the highly trained athletes have a faster response time. However, it remains to be determined whether the more rapid adjustment of $$\dot V_{{\text{O}}_{\text{2}} }$$ toward steady state in athletes is due to $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ differences or training adaptation alone. One approach to this problem is to study the time course of $$\dot V_{{\text{O}}_{\text{2}} }$$ kinetics at the onset of work in athletes who differ in $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ but have similar training habits. Therefore, the purpose of these experiments was to compare the time course of $$\dot V_{{\text{O}}_{\text{2}} }$$ kinetics at the onset of exercise in athletes with similar training routines but who differ in $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ . Ten subjects ( $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ range 50–70 ml · kg−1 · min−1) performed 6-minutes of cycle ergometer exercise at ∼50% $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ . Ventilation and gas exchange were monitored by open circuit techniques. The data were modeled with a single component exponential function incorporating a time delay, (T D ); $$\Delta \dot V_{{\text{O}}_{{\text{2}}f} } = \Delta \dot V_{{\text{O}}_{2ss} } {\text{ (1}} - e^{ - t - T_D /_{\tau )} }$$ , where Τ is the time constant $$\Delta \dot V_{{\text{O}}_{{\text{2}}f} }$$ is the increase in $$\dot V_{{\text{O}}_{\text{2}} }$$ at time t and $$\Delta \dot V_{{\text{O}}_{{\text{2ss}}} }$$ is the steady-rate increment above resting $$\dot V_{{\text{O}}_{\text{2}} }$$ . Kinetic analysis revealed a range of $$\dot V_{{\text{O}}_{\text{2}} }$$ half times from 21.6 to 36.0 s across subjects with a correlation coefficient of r=−0.80 (p〈0.05) between $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ and $$\dot V_{{\text{O}}_{\text{2}} }$$ half time. These data suggest that in highly trained indicivuals with similar training habits, those with a higher $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ achieve a more rapid $$\dot V_{{\text{O}}_{\text{2}} }$$ adjustment at the onset of work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00426150
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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