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Effect of exercise intensity and hypoxia on skeletal muscle AMPK signaling and substrate metabolism in humans
journal contribution
posted on 2006-04-01, 00:00 authored by Glenn WadleyGlenn Wadley, R Lee-Young, B Canny, C Wasuntarawat, Z Chen, Mark Hargreaves, B Kemp, G McConellWe compared in human skeletal muscle the effect of absolute vs. relative exercise intensity on AMP-activated protein kinase (AMPK) signaling and substrate metabolism under normoxic and hypoxic conditions. Eight untrained males cycled for 30 min under hypoxic conditions (11.5% O2, 111 ± 12 W, 72 ± 3% hypoxia VO2 peak; 72% Hypoxia) or under normoxic conditions (20.9% O2) matched to the same absolute (111 ± 12 W, 51 ± 1% normoxia VO2 peak; 51% Normoxia) or relative (to VO2 peak) intensity (171 ± 18 W, 73 ± 1% normoxia VO2 peak; 73% Normoxia). Increases (P < 0.05) in AMPK activity, AMPK{alpha} Thr172 phosphorylation, ACCbeta Ser221 phosphorylation, free AMP content, and glucose clearance were more influenced by the absolute than by the relative exercise intensity, being greatest in 73% Normoxia with no difference between 51% Normoxia and 72% Hypoxia. In contrast to this, increases in muscle glycogen use, muscle lactate content, and plasma catecholamine concentration were more influenced by the relative than by the absolute exercise intensity, being similar in 72% Hypoxia and 73% Normoxia, with both trials higher than in 51% Normoxia. In conclusion, increases in muscle AMPK signaling, free AMP content, and glucose disposal during exercise are largely determined by the absolute exercise intensity, whereas increases in plasma catecholamine levels, muscle glycogen use, and muscle lactate levels are more closely associated with the relative exercise intensity.
History
Journal
American journal of physiology : endocrinology and metabolismVolume
290Issue
4Publisher
American Physiological SocietyLocation
Bethesda, Md.Publisher DOI
ISSN
0193-1849eISSN
1522-1555Language
engPublication classification
C1.1 Refereed article in a scholarly journal; C Journal articleCopyright notice
2006, American Physiological SocietyUsage metrics
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