Background: Oxygen uptake at the anaerobic threshold (VO2AT) is considered as the main determinant for endurance performance in humans. Endurance performance steeply decreases with aging but seems to be kept exceedingly high in elite mountain runners. Methods: To obtain the age- and gender-related upper limits of endurance performance in this sport, we analyzed the results of the World Masters Athletic Championships in Mountain Running 2007. Additionally, to investigate the relationship between the individual VO2AT values and running times, laboratory tests were performed in 10 mountain runners. Results: The World Championships race times of the first 5 finishers of the 5-year age groups did not differ significantly from 35 to 49 years. The corresponding mean (± SD) values of the VO2AT were 68.0 ± 1.7 ml/min/kg in males and 58.1 ± 1.9 ml/min/kg in females. In the following age groups up to 70+ there was a decrease in the VO2AT of 29.1% in males and 33.9% in females. Conclusion: Thus, at the beginning of the 3rd millennium, elite mountain runners demonstrate that VO2AT and probably also VO2max may be held at top levels in humans up to the age of 45–49 years in both sexes. Despite the following decrease, endurance capacity remains about 3.5-fold higher in elite mountain runners up to 70+ years when compared to their untrained peers.
The F o F 1 -ATPase, a multisubunit protein complex of the inner mitochondrial membrane, produces most of the ATP in mammalian cells. Mitochondrial diseases as a result of a dysfunction of ATPase can be caused by mutations in mitochondrial DNA-encoded ATPase subunit a or rarely by an ATPase defect of nuclear origin. Here we present a detailed functional and immunochemical analysis of a new case of selective and generalized ATPase deficiency found in an Austrian patient. The defect manifested with developmental delay, muscle hypotonia, failure to thrive, ptosis, and varying lactic acidemia (up to 12 mmol/L) beginning from the neonatal period. A low-degree dilated cardiomyopathy of the left ventricle developed between the age of 1 and 2 y. A Ͼ90% decrease in oligomycin-sensitive ATPase activity and an 86% decrease in the content of the ATPase complex was found in muscle mitochondria. It was associated with a significant decrease of ADP-stimulated respiration of succinate (1.5-fold) and respiratory control with ADP (1.7-fold) in permeabilized muscle fibers, and with a slight decrease of the respiratory chain complex I and compensatory increase in the content of complexes III and IV. The same ATPase deficiency without an increase in respiratory chain complexes was found in fibroblasts, suggesting a generalized defect with tissue-specific manifestation. Absence of any mutations in mitochondrial ATP6 and ATP8 genes indicates a nuclear origin of the defect. Mitochondrial disorders caused by impairment of mitochondrial oxidative phosphorylation (OXPHOS) affect predominantly tissues with high-energy demands: muscle, brain, and heart. Subunits of OXPHOS complexes are encoded in two separate genomes: nuclear and mitochondrial. A pathogenic mutation in both genomes can cause an OX-PHOS defect. Defects in complex V-mitochondrial F o F 1 -ATPase are less frequent than the defects of the respiratory chain complexes, but they are mostly very severe and can be caused by mitochondrial DNA (mtDNA) mutations or by mutations in nuclear genes.Mitochondrial ATPase is a multisubunit complex composed of 16 different subunits (1). Six of these compose the globular F 1 part, which is responsible for enzymatic catalysis of ATP synthesis or hydrolysis. Ten remaining subunits form the membrane-spanning F o part, which performs H ϩ translocation across the inner mitochondrial membrane. Four subunits of F o form stalks that connect F 1 and F o parts. Only two subunits from F o part are encoded by mitochondrial genome: subunits a and A6L (subunits 6 and 8) (2). All of the other 14 subunits of the ATPase are encoded by the nuclear genes.Specific defects in mitochondrial ATPase are caused mainly by mtDNA mutations that affect subunit a; no mutations in subunit A6L have been described so far. The most frequent mutation in subunit a is T8993G mutation (3-7) or T8993C mutation (8)
PGC-1α (peroxisome proliferator-activated receptor γ co-activator 1α) is an important regulator of mitochondrial biogenesis and a master regulator of enzymes involved in oxidative phosphorylation. Recent evidence demonstrated that the Gly482Ser single nucleotide polymorphism (SNP) in the PGC-1α gene affects insulin sensitivity, blood lipid metabolism and binding to myocyte enhancer factor 2 (MEF2). Individuals carrying this SNP were shown to have a reduced cardiorespiratory fitness and a higher risk to develop type 2 diabetes. Here, we investigated the responses of untrained men with the Gly482Ser SNP to a 10 week programme of endurance training (cycling, 3 x 60 min/week, heart rate at 70-90% VO2peak). Quantitative data from analysis of biopsies from vastus lateralis muscle revealed that the SNP group, in contrast to the control group, lacked a training-induced increase in content of slow contracting oxidative fibres. Capillary supply, mitochondrial density, mitochondrial enzyme activities and intramyocellular lipid content increased similarly in both groups. These results indicate that the impaired binding of MEF2 to PGC-1α in humans with this SNP impedes exercise-induced fast-to-slow muscle fibre transformation.
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