Background: Parkinson’s disease (PD) is characterized by progressive loss of dopamine-producing neurons in the substantia nigra, leading to motor impairment. Current treatments offer symptomatic relief but do not alter disease progression.

Objective: A proof-of-concept study evaluated whether six months of high-intensity aerobic exercise could preserve—and potentially restore—dopaminergic neuron function in early-stage PD patients.

Methods: Ten individuals diagnosed with PD within the past four years participated in structured high-intensity interval training (HIFI), conducted three times weekly for six months via the online “Beat Parkinson’s Today” program. Target heart rates were monitored using wearable devices. Baseline and post-intervention neuroimaging (neuromelanin-sensitive MRI and dopamine transporter–PET scans) measured changes in substantia nigra neuromelanin and dopamine transporter (DAT) availability.

Results: Contrary to expected declines, nine out of ten participants demonstrated significant increases in both neuromelanin signal and DAT binding post-exercise. These findings suggest neuronal recovery or enhanced dopaminergic function. Increased imaging signals align with healthier dopamine-producing neurons—supporting the hypothesis that intense exercise may be neuroprotective or even neurorestorative.

Conclusion: High-intensity aerobic exercise may not only slow neurodegeneration in Parkinson’s disease but also reverse aspects of dopaminergic neuron dysfunction. While preliminary, these imaging-based results represent the first evidence of exercise-induced biological changes at the neuronal level in PD. Larger, controlled trials are needed to confirm these findings and explore exercise as a disease-modifying intervention.