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  • 1
    ISSN: 1439-6327
    Keywords: Physical fitness ; Maximal oxygen uptake ; Skeletal muscle enzymes ; Muscle fibers ; Body fat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary On the basis of maximal oxygen uptake ( $$\dot V$$ O2 max) 18 normal, healthy men were divided into two groups of equal size: moderately trained subjects (MTR) each having $$\dot V$$ O2 max below 65.0 ml·min−1·kg−1 body weight (54.0±8.3) and well trained subjects (WTR), whose $$\dot V$$ O2 max exceeded 65.0 ml·min−1·kg−1 body weight (69.2±4.1). The WTR group had slightly (non significant, n.s.) higher percentage of slow twitch, oxidative (SO) fibers in M. vastus lateralis and higher (n.s.) activities of cytochrome c oxidase (CytOx), succinate dehydrogenase (SDH), 3-hydroxyacyl-CoA-dehydrogenase (HADH), and citrate synthase (CS), while lactate dehydrogenase (LDH) activity was lower (n.s.). In the MTR group only, the SO-%, and the activities of CytOx, SDH and HADH correlated positively with $$\dot V$$ O2 max, and LDH negatively with $$\dot V$$ O2 max. These correlations were not significant in the WTR group possibly because of the adaptations produced by training in this group. Multiple regression analysis was used to elucidate the best combination of variables to explain the variance in $$\dot V$$ O2 max. The best model consisted of the sum of relative activities of oxidative muscle enzymes (CytOx, SDH, HADH, CS), muscle LDH activity, body fat content (% F) and lean body mass. This model explained 69% of the variance in $$\dot V$$ O2 max; and of the individual variables % F was of utmost importance.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 44 (1980), S. 245-254 
    ISSN: 1439-6327
    Keywords: Prolonged exercise ; Blood glucose ; Muscle glycogen ; Physical fitness ; Respiratory exchange ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Seven physically fit (well-trained, maximal oxygen uptake 69.6±4.4 ml×kg−1×min−1) and eight less fit (moderately trained, maximal oxygen uptake 56.1±5.7 ml×kg−1×min−1) healthy male subjects were exercised for 4 h by bicycle ergometry against a pedalling resistance calculated to cause oxygen consumption corresponding to approximately 30% of each individual's maximal oxygen uptake value. Respiratory exchange ratio was estimated at 1 h and blood glucose and lactate concentrations and muscle glycogen content at 2 h intervals. Muscle glycogen content decreased markedly during the first 2 h of exercise in the well-trained group but was similar after 4 h exercise in both groups. No major differences were observed between the two subject groups in blood variable concentrations. Calculations based on respiratory exchange ratio showed that the proportion of carbohydrates utilized in the total energy consumption was 14% in the physically fit group and 25% in the less fit group, thus supporting previous observations that more energy is derived by fat oxidation in well-trained than in less-trained individuals during submaximal work at relatively similar oxygen consumption levels.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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