A controlled, blinded, and randomized clinical study will be carried out in a large sample of people with Parkinson's disease, where the combined effects of physical exercise and transcranial direct curren stimlation (tDCS) on motor function will be evaluated.

Parkinson's disease (PD) is a neurological disease whose motor symptoms drastically affect the quality of life of those who suffer from it. There is currently high scientific evidence of the positive effect of physical exercise on the motor function of people with PD. This effect seems to be more relevant when this physical exercise is implemented with external sensory signals (eg visual, auditory). However, the neurophysiological mechanisms underlying these improvements induced by physical exercise are still unknown. It should also be noted that in recent years the simultaneous combination of physical exercise and transcranial direct current stimulation (tDCS) has begun to be explored, a non-invasive cortical neuromodulation technique that could enhance these positive effects of physical exercise. Up to now, the studies are few and have numerous methodological limitations to be able to confirm this potentiating effect of tDCS. In this project, a controlled, blinded, and randomized clinical study will be carried out in a large sample of people with PD, where the combined effects of physical exercise and tDCS on motor function will be evaluated. Using electrophysiological techniques (electroencephalography and transcranial magnetic stimulation), the possible neurophysiological mechanisms underlying the possible motor improvements found and their role in the processes of preparation and motor activation and synaptic plasticity will also be explored. The relevance of this study is twofold: i) on the one hand it will allow us to understand the movement control mechanisms that can be improved with physical exercise and thus allow us to develop more specific exercise programs in PD and ii) to know if the use of tDCS can enhance these benefits, thus opening a new therapeutic avenue in Parkinson's disease. Lastly, and taking into account that Parkinson's disease is the second most prevalent neurodegenerative disease, the results of this study may have a great impact on this group through a viable transfer to the social and health field.

Inclusion Criteria:

Clinical diagnosis of idiopathic Parkinson's disease, established according to the UK Parkinson's Disease Society Brain Bank Criteria.

Ability to understand and comply with study procedures.

Stable antiparkinsonian medication regimen prior to study participation.

Exclusion Criteria:

Significant cognitive impairment, defined as a score < 23 on the Mini-Mental State Examination (MMSE).

Below-average premorbid intelligence, defined as a score < 40 on the Vocabulary subtest of the Wechsler Adult Intelligence Scale - Third Edition (WAIS-III).

Clinically significant depression, defined as a score > 10 on the Geriatric Depression Scale (GDS-15).

Current treatment with cholinesterase inhibitors.

Presence of severe cardiovascular disease, including but not limited to:

Congestive heart failure

Ischemic heart disease

Cardiac pacemaker

Orthostatic hypotension

Uncontrolled diabetes mellitus.

History of stroke or traumatic brain injury.

History of seizure disorder or epilepsy.

Presence or prior implantation of a deep brain stimulation (DBS) device.

History of major orthopedic surgery that could interfere with motor performance or gait.

Presence of implanted electronic devices, including cardiac pacemakers, incompatible with study procedures.

Individual participant data will not be shared outside the research team. All analyses will be conducted by the study investigators. The dataset includes detailed neurophysiological, clinical, and kinematic data that could potentially allow participant re-identification.

Access to the data will therefore be restricted in accordance with data protection regulations and the informed consent provided by participants.