Velocity-based training (VBT) uses velocity rather than load to dictate training progressions; however, its impact on muscle structure in people with Parkinson’s disease (PD) remains undetermined. PURPOSE: The effects of VBT at 10% and 30% thresholds on changes in muscle thickness (MT), echo intensity (EI), fascicle angle (FA), shear wave elastography (SWE) and specific force (SF) and power (SP) of the left and right rectus femoris (RF) and vastus lateralis (VL) muscles were examined. METHODS: Subjects were split into 10% and 30% VT groups and underwent a 12-week VBT protocol. MT, EI, FA, SWE, SF, and SP were measured for left and right RF and VL using B-mode ultrasound before and after training. RESULTS: Mixed ANOVAs revealed significant time effects for MT with improvements in all muscles (p=.033; p=.003; p=.018; p=.038). For EI, the right RF (p=.020), left VL (p=.019), and right VL (p=.005) showed significant time effects, with all exhibiting decreases; group x time interactions were seen in the left RF, right RF and right VL with the right RF (p=.029) and right VL (p=.011) improving significantly more in the 30% VT group. There were significant time effects for FA in the right RF (p=.011) and SWE in the left RF (p =.013), both showing improvements. Significant time effects were indicated in RFSP with improvements in both legs (p=.040; p=.047). CONCLUSION: VBT is effective for improving muscle morphology in PD patients, especially for 30% VT.