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This Article Full Text Full Text (PDF) All Versions of this Article: 295/6/E1427    most recent 90428.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Benziane, B. Articles by Stepto, N. K. Search for Related Content PubMed PubMed Citation Articles by Benziane, B. Articles by Stepto, N. K.

Divergent cell signaling after short-term intensified endurance training in human skeletal muscle

¹Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institute, Stockholm, Sweden; ²Centre for Aging, Rehabilitation, Exercise, and Sport, Victoria University, Footscray, Victoria; and ³Department of Physiology, Monash University, Clayton, Victoria, Australia

Submitted 9 May 2008 ; accepted in final form 29 September 2008

Endurance training represents one extreme in the continuum of skeletal muscle plasticity. The molecular signals elicited in response to acute and chronic exercise and the integration of multiple intracellular pathways are incompletely understood. We determined the effect of 10 days of intensified cycle training on signal transduction in nine inactive males in response to a 1-h acute bout of cycling at the same absolute workload (164 ± 9 W). Muscle biopsies were taken at rest and immediately and 3 h after the acute exercise. The metabolic signaling pathways, including AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR), demonstrated divergent regulation by exercise after training. AMPK phosphorylation increased in response to exercise (16-fold; P < 0.05), which was abrogated posttraining (P < 0.01). In contrast, mTOR phosphorylation increased in response to exercise (2-fold; P < 0.01), which was augmented posttraining (P < 0.01) in the presence of increased mTOR expression (P < 0.05). Exercise elicited divergent effects on mitogen-activated protein kinase (MAPK) pathways after training, with exercise-induced extracellular signal-regulated kinase (ERK) 1/2 phosphorylation being abolished (P < 0.01) and p38 MAPK maintained. Finally, calmodulin kinase II (CaMKII) exercise-induced phosphorylation and activity were maintained (P < 0.01), despite increased expression (2-fold; P < 0.05). In conclusion, 10 days of intensified endurance training attenuated AMPK, ERK1/2, and mTOR, but not CaMKII and p38 MAPK signaling, highlighting molecular pathways important for rapid functional adaptations and maintenance in response to intensified endurance exercise and training.

adenosine 5'-monophosphate-activated protein kinase; protein kinase B; mitogen-activated protein kinases; calmodulin kinase II; mammalian target of rapamycin; glycogen

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