Please assess the completion status of the following clinical trial:

Trial Title: Effects of Aerobic Exercise in Parkinson's Disease

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: SINGLE
- Phase: None
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* Veteran or non-veteran;~* Presence of all 3 cardinal features of Parkinson's disease (resting tremor, bradykinesia, and rigidity), which have to be asymmetrical;~* Hoehn and Yahr Scale stage I-III;~* Men or women aged 50-80 capable of performing the planned exercise programs;~* Intention to remain in the local area over the study period;~* Stable dopaminergic treatment regimen for at least 4 weeks prior to baseline without any clinical need for medication adjustment at the time of screening~Exclusion Criteria:~* Secondary parkinsonism;~* Parkinson-plus syndromes;~* MMSE score \<24;~* Participating in a aerobic exercise program;~* An unstable dosage of drugs active in the central nervous system (e.g., anxiolytics, antidepressants) during the 60 days before the baseline visit;~* Participation in drug studies or the use of investigational drugs within 30 days before screening; structural brain disease;~* Active epilepsy;~* Acute illness or active, confounding medical, neurological, or musculoskeletal conditions; alcoholism or other forms of drug addiction;~* Inability to complete the graded exercise test;~* Lack of medical clearance from our pulmonologist;~* Intention to move or take a \>1 month vacation during the study period;~* Contraindications to MRI or claustrophobia requiring sedation

- Gender: ALL
- Minimum Age: 50 Years
- Maximum Age: 80 Years
- Healthy Volunteers: f

Study Arms:
- Continuous training (Type: ACTIVE_COMPARATOR): Aerobic walking using continuous heart rate training.
- Interval training (Type: ACTIVE_COMPARATOR): Aerobic walking using interval heart rate training

Based on this trial design, predict the completion outcome and termination type (if applicable).