Obesity (OB) disrupts cellular communication consistent with lower skeletal muscle capillarization. Exosomes, small microvesicles, transport and deliver mRNA, miRNA, and proteins in an endocrine manner and are released by muscle during aerobic exercise. The effects of resistance exercise (REx) on exosome biogenesis is unknown. PURPOSE: Investigate if resistance exercise increases skeletal muscle exosome biogenesis pathways and if this response is impaired in obesity. METHODS: Lean (LN) and obese (OB) (n=8/group) sedentary men and women performed 3 sets of 8-12 repetitions/set of acute, single leg knee extension resistance exercise at 80% of 1-RM. Vastus lateralis biopsies were obtained at rest and at 15 min, and 3 hr post-exercise. Muscle mRNA, protein expression, fiber typing, and capillary staining were measured. RESULTS: The gene expression of the exosome biogenesis components hepatocyte growth factor-regulated tyrosine kinase (HGS) and vacuolar protein sorting mutant (VPS4a) were lower in OB than LN at rest (~25%) and at 15 min post- (~20%), but not 3 hr post-exercise. Expression of exosome surface markers apoptotic linked gene-2 interacting protein X (Alix) was lower (OB ~35% and LN ~20% 15min post-exercise) and tumor susceptibility gene-101 (TSG-101) was higher (OB ~50% and LN ~40% 3hr post-exercise) in response to REx in both groups. Acute resistance exercise increased vascular endothelial growth factor (VEGF) mRNA similarly in LN and OB. Interestingly, anti-angiogenic thrombospondin-1 (TSP-1) mRNA was increased by acute REx only in OB (~230% 3hr post-exercise). miR-130a (angiogenesis), miR-206 (myoblast to myotube differentiation) and miR-503 (repressor of cell proliferation) were increased in OB at rest and following exercise. Type II fiber size was greater and capillary density was lower in OB. CONCLUSION: Obesity alters skeletal muscle exosome biogenesis, angiogenic, and muscle differentiation pathways possibly contributing to greater muscle fiber size and lower muscle capillarization. Resistance exercise alters skeletal muscle exosome marker expression similarly in both lean and obese.