The increase in intramyocellular lipid content is a very early response to training

V.B. Schrauwen-Hinderling, P. Schrauwen, M.K.C. Hesselink, J.M.A. van Engelshoven, K. Nicolay, W.H.M. Saris, A.G. Kessels, M.E. Kooi

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Abstract

Schrauwen-Hinderling VB, Schrauwen P, Hesselink MK, van Engelshoven JM, Nicolay K, Saris WH, Kessels AG, Kooi ME.

Department of Radiology, University Hospital Maastricht, 6229 HX Maastricht, The Netherlands. vhi@rdia.azm.nl

The present study investigated the influences of a 2-wk training program on intramyocellular lipid (IMCL) content, IMCL decrease during exercise, fat oxidation, and insulin sensitivity. Nine untrained men (age, 23.3 +/- 3.2 yr; body mass index, 22.6 +/- 2.6 kg/m(2); maximal power output, 3.8 +/- 0.6 W/kg body weight) trained for 2 wk. Before and after training, subjects cycled for 3 h while substrate oxidation was measured. IMCL content in the vastus lateralis muscle was determined before and after cycling by proton magnetic resonance spectroscopy. Before and after training, insulin sensitivity was assessed by an insulin tolerance test. The training period resulted in a significant increase in IMCL content by 42 +/- 14%. IMCL content decreased significantly during cycling. However, 2 wk of training were not sufficient to achieve increases in fat oxidation and/or use of IMCL during exercise. All markers used to test insulin sensitivity point toward improved insulin sensitivity, albeit not significant. We conclude that the increase in IMCL content is a very early response to training, preceding significant changes in insulin sensitivity. The results suggest that the presence of triglycerides alone does not necessarily have detrimental effects on insulin sensitivity. We confirm earlier reports that IMCL contributes to the energy used during prolonged submaximal exercise
Original languageEnglish
Pages (from-to)1610-1616
Number of pages6
JournalJournal of Clinical Endocrinology & Metabolism
Volume88
Issue number4
DOIs
Publication statusPublished - 1 Jan 2003

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