Abstract
Objective: Intramyocellular lipid (IMCL) storage negatively associates with insulin resistance, albeit not in endurance-trained athletes. We investigated the putative contribution of lipid droplet (LD) morphology and subcellular localization to the so-called athlete's paradox.
Methods: We performed quantitative immunofluorescent confocal imaging of muscle biopsy sections from endurance Trained, Lean sedentary, Obese, and Type 2 diabetes (T2DM) participants (n = 8/group). T2DM patients and Trained individuals were matched for IMCL content. Furthermore we performed this analysis in biopsies of T2DM patients before and after a 12-week exercise program (n = 8).
Results: We found marked differences in lipid storage morphology between trained subjects and T2DM: the latter group mainly store lipid in larger LDs in the subsarcolemmal (SS) region of type II fibers, whereas Trained store lipid in a higher number of LDs in the intramyofibrillar (IMF) region of type I fibers. In addition, a twelve-week combined endurance and strength exercise program resulted in a LD phenotype shift in T2DM patients partly towards an 'athlete-like' phenotype, accompanied by improved insulin sensitivity. Proteins involved in LD turnover were also more abundant in Trained than in T2DM and partly changed in an 'athlete-like' fashion in T2DM patients upon exercise training.
Conclusions: Our findings provide a physiological explanation for the athlete's paradox and reveal LD morphology and distribution as a major determinant of skeletal muscle insulin sensitivity. (C) 2018 The Authors. Published by Elsevier GmbH.
Original language | English |
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Pages (from-to) | 71-81 |
Number of pages | 11 |
Journal | Molecular Metabolism |
Volume | 17 |
DOIs | |
Publication status | Published - Nov 2018 |
Keywords
- Insulin sensitivity
- Athlete's paradox
- Intramyocellular lipid
- Lipid droplets
- INTRAMUSCULAR TRIGLYCERIDE BREAKDOWN
- HUMAN SKELETAL-MUSCLE
- INSULIN SENSITIVITY
- SPRINT INTERVAL
- ADIPOSE-TISSUE
- SEDENTARY MEN
- WEIGHT-LOSS
- PERILIPIN 2
- MITOCHONDRIA
- FIBERS