264-LB: Aerobic Exercise Training Reorganizes Skeletal Muscle Mitochondrial and Lipid Droplet Architecture

Exercise is a known intervention to alleviate insulin resistance. This study investigated how a 12-week endurance exercise intervention changes skeletal muscle mitochondrial and lipid droplet architecture in patients with type 2 diabetes. Participants completed 12 weeks of endurance exercise at 70% of their VO2 max five days a week at one hour a day. Muscle biopsies were taken before and 72 hours after the last exercise session. A subset of these muscle biopsies from two participants (58±0 years, 42.3±3.3 BMI, 2.5±0.7 medications, 8.2±0.1% HbA1c) was imaged using focused ion-beam scanning electron microscopy. Due to these results being preliminary, general trends are discussed. A deep-learning model segmented 14,197 mitochondria and 4,400 lipid droplets to assess individual mitochondrial and lipid droplet 3D structures, and mitochondria-to-lipid interactions. Surprisingly, exercise did not change individual mitochondrial and lipid droplet volume, surface area to volume ratio, or sphericity. There was an increase in mitochondria-to-mitochondria and mitochondria-to-lipid droplet interactions after endurance training. These preliminary data suggest that exercise may relieve insulin-resistant skeletal muscle by increasing the connectivity among mitochondria and lipid droplets prior to changing individual organelle morphology. Further analyses are ongoing to confirm these findings.