Relationship between work rate and oxygen uptake in mitochondrial myopathy during ramp-incremental exercise

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dc.contributor.authorGimenes, Ana Cristina Oliveira [UNIFESP]
dc.contributor.authorNeder, Jose Alberto [UNIFESP]
dc.contributor.authorDal Corso, Simone [UNIFESP]
dc.contributor.authorNogueira, Cristiano Rabelo [UNIFESP]
dc.contributor.authorNápolis, Lara Maris [UNIFESP]
dc.contributor.authorMello, Marco Tulio de [UNIFESP]
dc.contributor.authorOliveira, Acary Souza Bulle [UNIFESP]
dc.contributor.authorNery, Luiz Eduardo [UNIFESP]
dc.contributor.institutionUniversidade Federal de São Paulo (UNIFESP)
dc.date.accessioned2015-06-14T13:43:01Z
dc.date.available2015-06-14T13:43:01Z
dc.date.issued2011-04-01
dc.description.abstractWe determined the response characteristics and functional correlates of the dynamic relationship between the rate (Δ) of oxygen consumption ( <img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1188>O2) and the applied power output (work rate = WR) during ramp-incremental exercise in patients with mitochondrial myopathy (MM). Fourteen patients (7 males, age 35.4 ± 10.8 years) with biopsy-proven MM and 10 sedentary controls (6 males, age 29.0 ± 7.8 years) took a ramp-incremental cycle ergometer test for the determination of the <img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1189>O2 on-exercise mean response time (MRT) and the gas exchange threshold (GET). The Δ<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1190>O2/ΔWR slope was calculated up to GET (S1), above GET (S2) and over the entire linear portion of the response (S T). Knee muscle endurance was measured by isokinetic dynamometry. As expected, peak <img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1191>O2 and muscle performance were lower in patients than controls (P < 0.05). Patients had significantly lower Δ<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1192>O2/ΔWR than controls, especially the S2 component (6.8 ± 1.5 vs 10.3 ± 0.6 mL·min-1·W-1, respectively; P < 0.001). There were significant relationships between Δ<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1193>O2/ΔWR (S T) and muscle endurance, MRT-<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1194>O2, GET and peak <img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1195>O2 in MM patients (P < 0.05). In fact, all patients with Δ<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1196>O2/ΔWR below 8 mL·min-1·W-1 had severely reduced peak <img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1197>O2 values (<60% predicted). Moreover, patients with higher cardiopulmonary stresses during exercise (e.g., higher Δ ventilation/carbon dioxide output and Δ heart rate/Δ<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1198>O2) had lower Δ<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1199>O2/ΔWR (P < 0.05). In conclusion, a readily available, effort-independent index of aerobic dysfunction during dynamic exercise (Δ<img border=0 width=11 height=13 src=548_files/image001.gif v:shapes=_x0000_i1200>O2/ΔWR) is typically reduced in patients with MM, being related to increased functional impairment and higher cardiopulmonary stress.en
dc.description.affiliationUniversidade Federal de São Paulo (UNIFESP) Departamento de Medicina Disciplina de Pneumologia
dc.description.affiliationUniversidade Federal de São Paulo (UNIFESP) Setor de Doenças Neuromusculares
dc.description.affiliationUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Psicobiologia
dc.description.affiliationUnifespUNIFESP, Depto. de Medicina Disciplina de Pneumologia
dc.description.affiliationUnifespUNIFESP, Setor de Doenças Neuromusculares
dc.description.affiliationUnifespUNIFESP, EPM, Depto. de Psicobiologia
dc.description.sourceSciELO
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
dc.format.extent354-360
dc.identifierhttp://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011000400013
dc.identifier.citationBrazilian Journal of Medical and Biological Research. Associação Brasileira de Divulgação Científica, v. 44, n. 4, p. 354-360, 2011.
dc.identifier.fileS0100-879X2011000400013.pdf
dc.identifier.issn0100-879X
dc.identifier.scieloS0100-879X2011000400013
dc.identifier.urihttp://repositorio.unifesp.br/handle/11600/6403
dc.identifier.wosWOS:000289368400013
dc.language.isoeng
dc.publisherAssociação Brasileira de Divulgação Científica
dc.relation.ispartofBrazilian Journal of Medical and Biological Research
dc.rightsinfo:eu-repo/semantics/openAccess
dc.subjectMuscular diseasesen
dc.subjectOxygen consumptionen
dc.subjectCardiopulmonary exercise testingen
dc.subjectSkeletal muscleen
dc.subjectPathophysiologyen
dc.subjectMitochondrial myopathyen
dc.titleRelationship between work rate and oxygen uptake in mitochondrial myopathy during ramp-incremental exerciseen
dc.typeinfo:eu-repo/semantics/article
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