Intramyocellular lipids: anthropometric determinants and relationships with maximal aerobic capacity and insulin sensitivity.

Abstract

The existence of metabolically relevant intramyocellular lipids (IMCL) as assessed by the noninvasive (1)H-magnetic resonance spectroscopy (MRS) has been established. In the present studies, we analyzed the relationships between IMCL in two muscle types [the predominantly nonoxidative tibialis muscle (tib) and the predominantly oxidative soleus muscle (sol)] and anthropometric data, aerobic capacity (VO(2)max, bicycle ergometry, n = 77) and insulin sensitivity (hyperinsulinemic euglycemic clamp, n = 105) using regression analysis. In univariate regression, IMCL (tib) was weakly but significantly correlated with percentage of body fat (r = 0.28, P = 0.01), whereas IMCL (sol) was better correlated with waist-to-hip ratio (r = 0.41, P < 0.0001). No significant univariate correlation with age or maximal aerobic power was observed. After adjusting for adiposity, IMCL (tib) was positively correlated with measures of aerobic fitness. A significant interaction term between VO(2)max and percentage of body fat on IMCL (tib) (P = 0.04) existed (whole model r(2) = 0.26, P = 0.001). In contrast, aerobic fitness did not influence IMCL (sol). No correlation between insulin sensitivity as such and IMCL (tib) (r = -0.13, P = 0.2) or IMCL (sol) (r = 0.03, P = 0.72) was observed. Nethertheless, a significant interaction term between VO(2)max and IMCL on insulin sensitivity existed [P = 0.04 (tib) and P = 0.02 (sol)]; [whole model (sol) r(2) = 0.61, P < 0.0001, (tib) r(2) = 0.60, P < 0.0001]. In conclusion, obesity and aerobic fitness are important determinants of IMCL. IMCL and insulin sensitivity are negatively correlated in untrained subjects. The correlation between the two parameters is modified by the extent of aerobic fitness and cannot be found in endurance trained subjects. Thus, measurements of aerobic fitness and body fat are indispensable for the interpretation of IMCL and its relationship with insulin sensitivity.

• Authors: Claus Thamer, Jürgen Machann, Oliver Bachmann, Michael Haap, Dominik Dahl, Beate Wietek, Otto Tschritter, Andreas Niess, Klaus Brechtel, Andreas Fritsche, Claus Claussen, Stephan Jacob, Fritz Schick, Hans-Ulrich Häring, Michael Stumvoll
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 88 Issue 4 Pg. 1785-91 (Apr 2003) ISSN: 0021-972X [Print] United States
• PMID: 12679474 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Blood Glucose
• Insulin
• Lipids

Topics

• Adipose Tissue
• Adult
• Anthropometry
• Blood Glucose (analysis)
• Body Composition
• Female
• Glucose Clamp Technique
• Humans
• Insulin (blood)
• Insulin Resistance
• Lipids (analysis)
• Magnetic Resonance Spectroscopy
• Male
• Muscle, Skeletal (chemistry, ultrastructure)
• Obesity (physiopathology)
• Oxidation-Reduction
• Oxygen Consumption
• Physical Endurance
• Physical Fitness