title: Skeletal muscle reoxygenation after high-intensity exercise in mitochondrial myopathy.
abstract: This study addressed whether O(2) delivery during recovery from high-intensity, supra-gas exchange threshold exercise would be matched to O(2) utilization at the microvascular level in patients with mitochondrial myopathy (MM). Off-exercise kinetics of (1) pulmonary O(2) uptake VO(2P) (2) an index of fractional O(2) extraction by near-infrared spectroscopy (Δ[deoxy-Hb + Mb]) in the vastus lateralis and (3) cardiac output (Q'(T)) by impedance cardiography were assessed in 12 patients with biopsy-proven MM (chronic progressive external ophthalmoplegia) and 12 age- and gender-matched controls. Kinetics of VO(2P) were significantly slower in patients than controls (τ = 53.8 ± 16.5 vs. 38.8 ± 7.6 s, respectively; p < 0.05). Q'(T), however, declined at similar rates (τ = 64.7 ± 18.8 vs. 73.0 ± 21.6 s; p > 0.05) being typically slower than [Formula: see text] in both groups. Importantly, Δ[deoxy-Hb + Mb] dynamics (MRT) were equal to, or faster than, τVO(2P) in patients and controls, respectively. In fact, there were no between-group differences in τVO(2P)MRTΔ[deoxy-Hb + Mb] (1.1 ± 0.4 vs. 1.0 ± 0.2, p > 0.05) thereby indicating similar rates of microvascular O(2) delivery. These data indicate that the slower rate of recovery of muscle metabolism after high-intensity exercise is not related to impaired microvascular O(2) delivery in patients with MM. This phenomenon, therefore, seems to reflect the intra-myocyte abnormalities that characterize this patient population.
authors: Division of Respiratory Medicine, Department of Medicine, Pulmonary Function and Clinical Exercise Physiology Unit, Federal University of Sao Paulo, Paulista School of Medicine, Rua Botucatu, 740 3rd floor, Vila Clementino, Sao Paulo, Sao Paulo CEP 04023-062, Brazil. danielamanzoli@hotmail.com
authors: Daniela M
authors: DM
authors: Bravo
authors: Ana Cristina
authors: AC
authors: Gimenes
authors: Rúbia B
authors: RB
authors: Nascimento
authors: Eloara V M
authors: EV
authors: Ferreira
authors: Ana Cristina B
authors: AC
authors: Siqueira
authors: Ethiane D S
authors: ED
authors: Meda
authors: J Alberto
authors: JA
authors: Neder
authors: Luiz Eduardo
authors: LE
authors: Nery
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007700:Kinetics; D008297:Male; D017240:Mitochondrial Myopathies / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared