Muscle mitochondrial capacity exceeds maximal oxygen delivery in humans

TY - JOUR

T1 - Muscle mitochondrial capacity exceeds maximal oxygen delivery in humans

AU - Boushel, Robert Christopher

AU - Gnaiger, Erich

AU - Calbet, Jose A L

AU - Gonzalez-Alonso, Jose

AU - Wright-Paradis, Cynthia

AU - Sondergaard, Hans

AU - Ara, Ignacio

AU - Helge, Jørn W

AU - Saltin, Bengt

N1 - Copyright © 2010 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

PY - 2011/3

Y1 - 2011/3

N2 - Across a wide range of species and body mass a close matching exists between maximal conductive oxygen delivery and mitochondrial respiratory rate. In this study we investigated in humans how closely in-vivo maximal oxygen consumption (VO2 max) is matched to state 3 muscle mitochondrial respiration. High resolution respirometry was used to quantify mitochondrial respiration from the biopsies of arm and leg muscles while in-vivo arm and leg VO2 were determined by the Fick method during leg cycling and arm cranking. We hypothesized that muscle mitochondrial respiratory rate exceeds that of systemic oxygen delivery. The state 3 mitochondrial respiration of the deltoid muscle (4.3±0.4mmolo2kg-1min-1) was similar to the in-vivo VO2 during maximal arm cranking (4.7±0.5mmolO2kg-1min-1) with 6kg muscle. In contrast, the mitochondrial state 3 of the quadriceps was 6.9±0.5mmolO2kg-1min-1, exceeding the in-vivo leg VO2 max (5.0±0.2mmolO2kg-1min-1) during leg cycling with 20kg muscle (P<0.05). Thus, when half or more of the body muscle mass is engaged during exercise, muscle mitochondrial respiratory capacity surpasses in-vivo VO2 max. The findings reveal an excess capacity of muscle mitochondrial respiratory rate over O2 delivery by the circulation in the cascade defining maximal oxidative rate in humans.

AB - Across a wide range of species and body mass a close matching exists between maximal conductive oxygen delivery and mitochondrial respiratory rate. In this study we investigated in humans how closely in-vivo maximal oxygen consumption (VO2 max) is matched to state 3 muscle mitochondrial respiration. High resolution respirometry was used to quantify mitochondrial respiration from the biopsies of arm and leg muscles while in-vivo arm and leg VO2 were determined by the Fick method during leg cycling and arm cranking. We hypothesized that muscle mitochondrial respiratory rate exceeds that of systemic oxygen delivery. The state 3 mitochondrial respiration of the deltoid muscle (4.3±0.4mmolo2kg-1min-1) was similar to the in-vivo VO2 during maximal arm cranking (4.7±0.5mmolO2kg-1min-1) with 6kg muscle. In contrast, the mitochondrial state 3 of the quadriceps was 6.9±0.5mmolO2kg-1min-1, exceeding the in-vivo leg VO2 max (5.0±0.2mmolO2kg-1min-1) during leg cycling with 20kg muscle (P<0.05). Thus, when half or more of the body muscle mass is engaged during exercise, muscle mitochondrial respiratory capacity surpasses in-vivo VO2 max. The findings reveal an excess capacity of muscle mitochondrial respiratory rate over O2 delivery by the circulation in the cascade defining maximal oxidative rate in humans.

KW - Adult

KW - Female

KW - Humans

KW - Male

KW - Mitochondria, Muscle

KW - Oxygen

U2 - 10.1016/j.mito.2010.12.006

DO - 10.1016/j.mito.2010.12.006

M3 - Journal article

C2 - 21147270

SN - 1567-7249

VL - 11

SP - 303

EP - 307

JO - Mitochondrion

JF - Mitochondrion

IS - 2

ER -