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Consecutive bouts of diverse contractile activity alter acute responses in human skeletal muscle

¹Exercise Metabolism Group, School of Medical Science, RMIT University, Melbourne, Australia; ²Copenhagen Muscle Research Centre and Centre of Inflammation and Metabolism, Department of Biology, University of Copenhagen, Denmark; ³Exercise, Muscle, and Metabolism Unit, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia; and ⁴School of Human Movement & Sport Sciences, University of Ballarat, Victoria, Australia

Submitted 11 September 2008 ; accepted in final form 19 January 2009

We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men [22.9 ± 6.3 yr, body mass of 73.2 ± 4.5 kg, peak O₂ uptake (O_2peak) of 54.0 ± 5.7 ml·kg^–1·min^–1] were randomly assigned to complete trials consisting of either resistance exercise (8 x 5 leg extension, 80% 1 repetition maximum) followed by a bout of endurance exercise (30 min cycling, 70% O_2peak) or vice versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout, and after 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1^Ser473 were elevated 15 min after resistance exercise compared with cycling, with the greatest increase observed when resistance exercise followed cycling (55%; P < 0.01). TSC2-mTOR-S6 kinase phosphorylation 15 min after each bout of exercise was similar regardless of the exercise mode. The cumulative effect of combined exercise resulted in disparate mRNA responses. IGF-I mRNA content was reduced when cycling preceded resistance exercise (–42%), whereas muscle ring finger mRNA was elevated when cycling was undertaken after resistance exercise (52%; P < 0.05). The hexokinase II mRNA level was higher after resistance cycling (45%; P < 0.05) than after cycling-resistance exercise, whereas modest increases in peroxisome proliferator-activated receptor gamma coactivator-1 mRNA did not reveal an order effect. We conclude that acute responses to diverse bouts of contractile activity are modified by the exercise order. Moreover, undertaking divergent exercise in close proximity influences the acute molecular profile and likely exacerbates acute "interference."

endurance; resistance exercise; acute responses; concurrent training

This article has been cited by other articles:

				V. G. Coffey, B. Jemiolo, J. Edge, A. P. Garnham, S. W. Trappe, and J. A. Hawley Effect of consecutive repeated sprint and resistance exercise bouts on acute adaptive responses in human skeletal muscle Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2009; 297(5): R1441 - R1451. [Abstract] [Full Text] [PDF]