To investigate if resistance training exercises performed twice a week with or without gym equipment assistance in a 12-week period could improve balance in patients with Parkinson Disease (PD).

Methods: Sixty three patients with idiopathic PD (Hoehn and Yahr stage II - III) and preserved cognitive function will participate in this study. Patients will be randomized among three intervention groups: resistance training with free weights, resistance training with gym equipment and control group. Investigators will use static platform balance variables to assess the primary end-point outcome measures. For the secondary outcomes measures, most common clinical functional balances tests for PD will be applied: Berg Balance Scale (BBS), Mini-BESTest - Balance Evaluation (Mini-BESTest), Timed Up and Go test (TUG) and variables from dynamic posturography.

Parkinson's disease is a progressive neurodegenerative disease that affects motor functions and is characterized by bradykinesia, resting tremor, rigidity, and postural instability. Despite of pharmacological treatments, patients remain with deficits in balance, gait, autonomic system functions and cognition which impact on their quality of life.

The effects of resistance training on PD are still controversial when balance and improvement on functional tests are the targets.

Since the results of previous studies about resistance training on balance are still controversial, more interventions are required to address the question if strengthening exercise may improve or not the balance of PD patients. Our exercises will target the trunk, leg and shoulder muscles because of their contribution on patient's posture.

Inclusion Criteria:

• Age between 50 to 75 years old;
• Hoehn and Yahr stages II or III;
• Idiopathic Parkinson disease diagnosed according to the United Kingdom Parkinson's Disease Society Brain Research Centre Criteria, Institute of Neurology, London;
• Ability to walk independently without walking devices aid;
• Absence of orthopedic injuries or pain in joints that could interfere on training program;
• Stable medication regimen for PD treatment at recruitment stage;
• Mini Mental State Examination Scale (MMSE) ≥ to 27 for literate patients and schooling ≥ of 4 years of formal education;
• No cardiovascular instability;
• No pacemaker, decompensated metabolic disease, vestibular dysfunction, and stroke;
• Availability to come to the clinic twice a week;
• Not participating in other physical rehabilitation programs during and six months prior to the study.

Exclusion Criteria:

• Patients will be excluded if they refuse to participate, do not sign the consent form, have a diagnosis of secondary parkinsonism or present cognitive impairment.