<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>1981-4690</journal-id>
<journal-title><![CDATA[Revista Brasileira de Educação Física e Esporte]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. Bras. Educ. Fís. Esporte]]></abbrev-journal-title>
<issn>1981-4690</issn>
<publisher>
<publisher-name><![CDATA[Escola de Educação Física e Esporte da Universidade de São Paulo  ]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1981-46902014000400683</article-id>
<article-id pub-id-type="doi">10.1590/1807-55092014000400683</article-id>
<title-group>
<article-title xml:lang="pt"><![CDATA[Teto metabólico como indicador de capacidade de tolerância ao esforço físico: importância da capacidade oxidativa de reserva]]></article-title>
<article-title xml:lang="en"><![CDATA[Metabolic ceiling as indicative of endurance capacity: importance of reserve oxidative capacity]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Pereira]]></surname>
<given-names><![CDATA[Benedito]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidade de São Paulo Escola de Educação Física e Esporte ]]></institution>
<addr-line><![CDATA[São Paulo SP]]></addr-line>
<country>Brazil</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>12</month>
<year>2014</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>12</month>
<year>2014</year>
</pub-date>
<volume>28</volume>
<numero>4</numero>
<fpage>683</fpage>
<lpage>689</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://educa.fcc.org.br/scielo.php?script=sci_arttext&amp;pid=S1981-46902014000400683&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://educa.fcc.org.br/scielo.php?script=sci_abstract&amp;pid=S1981-46902014000400683&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://educa.fcc.org.br/scielo.php?script=sci_pdf&amp;pid=S1981-46902014000400683&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="pt"><p><![CDATA[Comparados com outras esp&#233;cies animais, a capacidade para a resist&#234;ncia de seres humanos &#233; not&#225;vel. A tese dos fatores limitantes e determinantes da resist&#234;ncia considera vari&#225;veis como consumo m&#225;ximo de oxig&#234;nio (VO2max), limiares metab&#243;licos e economia de movimento as mais importantes para a efetiva&#231;&#227;o de exerc&#237;cios f&#237;sicos de longa dura&#231;&#227;o. Como o oxig&#234;nio (O2) e produtos do metabolismo de substratos (glicose e &#225;cidos graxos) s&#227;o utilizados no interior de mitoc&#244;ndrias do tecido muscular para obten&#231;&#227;o de energia por processos oxidativos durante esse tipo de exerc&#237;cio f&#237;sico, esta &#233; outra vari&#225;vel importante a ser considerada. O objetivo deste texto &#233; demonstrar que a incid&#234;ncia de fadiga em exerc&#237;cios f&#237;sicos prolongados intensos pode estar relacionada com modifica&#231;&#245;es negativas ocorridas no potencial oxidativo mitocondrial. A funcionalidade mitocondrial encontra-se situada entre limites extremos que correspondem aos estados 4 (repouso) e 3 (VO2max). A tese desse texto &#233; a de que quando essa vari&#225;vel aproxima-se do estado 3 durante o exerc&#237;cio f&#237;sico prolongado intenso, o organismo esgota suas possibilidades de produ&#231;&#227;o de energia pela fosforila&#231;&#227;o oxidativa, com consequente modifica&#231;&#245;es nos valores de limiares metab&#243;licos e no percentual do VO2max utilizado durante o esfor&#231;o f&#237;sico. Portanto, mitoc&#244;ndrias funcionam como um termostato bioenerg&#233;tico celular durante situa&#231;&#245;es como as que envolvem o exerc&#237;cio f&#237;sico intenso prolongado.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Compared with other animal species, the endurance capacity of humans is remarkable. The thesis of limiting and determining factors of endurance consider variables such as maximum oxygen (O2) consumption (VO2max), metabolic thresholds and movement economy the most importants. As the O2 and metabolic products of substrates (glucose and fatty acids) are used in muscle&#180;s mitochondria to obtain energy by oxidative processes during long duration exercise, this is another important variable to be considered. The aim of this assay is to show that the incidence of fatigue in this kind of exercise might be related to negative changes in mitochondrial oxidative potential. Mitochondrial oxidative potential is situated between the extreme limits of its functionality, which correspond to the states 4 (rest) and 3 (VO2max). The thesis put forward here is that when this variable is close to the state 3 during prolonged intense exercise, the body depletes their possibilities to produce energy through oxidative phosphorilation, with consequent changes in metabolic thresholds and increase in the percent of VO2max used in this condition. Therefore, mitochondria function as a cellular bioenergetic thermostat during situations such as those involving prolonged strenuous exercise.]]></p></abstract>
<kwd-group>
<kwd lng="pt"><![CDATA[Fadiga]]></kwd>
<kwd lng="pt"><![CDATA[Metabolismo]]></kwd>
<kwd lng="pt"><![CDATA[Mitocôndria]]></kwd>
<kwd lng="pt"><![CDATA[Resistência]]></kwd>
<kwd lng="en"><![CDATA[Fatigue]]></kwd>
<kwd lng="en"><![CDATA[Metabolism]]></kwd>
<kwd lng="en"><![CDATA[Mitochondria]]></kwd>
<kwd lng="en"><![CDATA[Endurance]]></kwd>
</kwd-group>
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