Tendon integrity depends on controlled extracellular matrix production and adaptation to mechanical load. Dysregulated hypoxia-inducible factor 1α (HIF1α) signaling has been linked to human tendon disease. To investigate the effects of chronic HIF1α activation and to compare responses between load-bearing Achilles tendons and positional tail tendon fascicles, we generated a tendon-specific VHL knockout in SCX-positive cells and performed label-free proteomics to characterize matrix remodeling.