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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
    Precision of ventilatory and gas exchange alterations as a predictor of the anaerobic threshold (1984)
    Springer
    European journal of applied physiology 52 (1984), S. 173-177 
    Details
    ISSN: 1439-6327
    Keywords: Anaerobic threshold ; Ventilatory threshold ; Exercise ventilation ; Gas exchange ; Blood lactate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Anaerobic threshold has been defined as the oxygen uptake ( $$\dot V_{{\text{O}}_{\text{2}} }$$ ) at which blood lactate (La) begins to rise systematically during graded exercise (Davis et al. 1982). It has become common practice in the literature to estimate the anaerobic threshold by using ventilatory and/or gas exchange alterations. However, confusion exists as to the validity of this practice. The purpose of this study was to examine the precision with which ventilatory and gas exchange techniques for determining anaerobic threshold predicted the anaerobic threshold resolved by La criteria. The anaerobic threshold was chosen using three criteria: (1) systematic increase in blood La (ATLa), (2) systematic increase in ventilatory equivalent for O2 with no change in the ventilatory equivalent for CO2 ( $${\text{AT}}_{\dot V_{\text{E}} } /\dot V_{{\text{O}}_{\text{2}} }$$ ), and (3) non-linear increase in expired ventilation graphed as a function of $$\dot V_{{\text{O}}_{\text{2}} }$$ ( $${\text{AT}}_{\dot V_{\text{E}} }$$ ). Thirteen trained male subjects performed an incremental cycle ergometer test to exhaustion in which the load was increased by 30 W every 3 minutes. Ventilation, gas exchange measures, and blood samples for La analysis were obtained every 3rd min throughout the test. In five of the thirteen subjects tested the anaerobic threshold determined by ventilatory and gas exchange alterations did not occur at the same $$\dot V_{{\text{O}}_{\text{2}} }$$ as the ATLa. The highest correlation between a gas exchange anaerobic threshold and ATLa was found for $${\text{AT}}_{\dot V_{\text{E}} } /\dot V_{{\text{O}}_{\text{2}} }$$ and was r=0.63 (P〈0.05). These data provide evidence that the ATLa and $${\text{AT}}_{\dot V_{\text{E}} }$$ do not always occur simultaneously and suggest limitations in using ventilatory or gas exchange measures to estimate the ATla.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00433388
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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