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Standardized protocol for a depletion of intramyocellular lipids (IMCL)

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2010
Author Ith Michael, Huber Philipp M., Egger Andrea, Schmid Jean Paul, Kreis Roland, Christ Emanuel R., Boesch Chris,
Project Multi-nuclear magnetic resonance spectroscopy (MRS) and imaging (MRI) on a clinical whole-body MR-system: insulin resistance, ageing, and physical activity
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Original article (peer-reviewed)

Journal NMR in Biomedicine
Volume (Issue) 23(5)
Page(s) 532 - 538
Title of proceedings NMR in Biomedicine
DOI 10.1002/nbm.1492

Abstract

Intramyocellular lipids (IMCL) are flexible fuel stores that are depleted by physical exercise and replenished by fat intake. IMCL or their degradation products are thought to interfere with insulin signaling thereby contributing to insulin resistance. From a practical point of view it is desirable to deplete IMCL prior to replenishing them. So far, it is not clear for how long and at which intensity subjects have to exercise in order to deplete IMCL.We therefore aimed at developing a standardized exercise protocol that is applicable to subjects over a broad range of exercise capacity and insulin sensitivity and allows measuring reliably reduced IMCL levels. Twelve male subjects, including four diabetes type 2 patients, with wide ranges of exercise capacity (VO 2peak per total body weight 27.9-55.8 ml*kg -1*min-1), insulin sensitivity (glucose infusion rate per lean body mass 4.7-15.3mg*min-1*kg -1), and BMI (21.7-31.5 kg*m-2), respectively, were enrolled. Using 1H magnetic resonance spectroscopy ( 1H-MRS), IMCL was measured in m.tibialis anterior and m.vastus intermedius before and during a depletion protocol of a week, consisting of a moderate additional physical activity (1 h daily at 60% VO2peak) and modest low-fat (10-15%) diet. Absolute IMCL-levels were significantly reduced in both muscles during the first 3 days and stayed constant for the next 3 days of an identical diet/exercise-scheme. These reduced IMCL levels were independent of insulin sensitivity, yet a tendency to lower depleted IMCL levels has been observed in subjects with higher VO2peak. The proposed protocol is feasible in subjects with large differences in exercise capacity, insulin sensitivity, and BMI, leading to reduced IMCL levels that neither depend on the exact duration of the depletion protocol nor on insulin sensitivity. This allows for a standardized preparation of IMCL levels either for correlation with other physiological parameters or for replenishment studies. Copyright © 2010 John Wiley & Sons, Ltd.
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