This study aims to test the feasibility and acceptability of home-based motor-motor dual-task training and motor-cognitive dual-task training interventions, and balance-related outcome measures which may be used in an anticipated future randomized control trial intended to determine the superiority of these dual-task training interventions.

Parkinson's disease (PD) is a complex, progressive neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the basal ganglia. Balance impairment is one of the major problems in people with PD, often manifested at a stage of mild to moderate disease severity.

Balance impairments in people with PD affect different domains of balance control: (1) postural sway during quiet stance, (2) automatic postural responses to external perturbations, (3) anticipatory postural adjustment, such as is seen before gait initiation (APAs), and (4) dynamic balance during walking. Therefore, it is important to focus on upright, bipedal balance in people with PD.

Physiotherapy approaches have found to be effective in improving balance-related motor impairments in people with PD. Dual-task training is one of these physiotherapy approaches. This involves simultaneous performance of a primary task and a second discrete task which is independent from the primary task. The primary task is usually a motor task like standing or walking, and the secondary task is either a motor task or a cognitive task such as carrying an object or talking. Dual-task training (DTT) has demonstrated to be effective in enhancing balance control and promoting interactions between the motor and cognitive systems. Two systematic reviews have been undertaken in this area. One found DTT improved balance in people with mild to moderate PD. The second included a meta-analysis, reporting a moderate effect in favor of DTT group on functional balance. However, there remains a lack of evidence about the superiority of motor-motor dual-task training (M-DTT) versus motor-cognitive dual-task training (C-DTT) in terms of improving balance.

A scoping review which is a part of this project shows that only one study compares the effectiveness of M-DTT and C-DTT on balance but this study has some methodological limitations. So, there is a need for a future randomized control trial to investigate the superiority of M-DTT and C-DTT on balance in people with PD.

The COVID-19 pandemic has shifted physiotherapy deliveries to telerehabilitation . A recent systematic review showed that telerehabilitation is feasible for people with PD and effective in improving and/or maintaining balance and gait and some non-motor aspects (quality of life, patient satisfaction) of the disease. So, DTT delivered to people in their homes via telerehabilitation may be an applicable alternative to traditional face-to-face physiotherapy service delivery.

The scoping review showed that there is some published evidence about home-based DTT, but no studies have investigated and compared the effectiveness of M-DTT and C-DTT interventions on balance in people with mild-moderate PD. For instance, one case study used C-DTT as a part of exergaming plus treadmill intervention in a home setting, but they only applied C-DTT, and there was no other type of DTT as a comparison in their study.

So, this study aims to test the feasibility and acceptability of the M-DTT and C-DTT interventions, and balance-related outcome measures which may be used in an anticipated future randomized control study intended to determine the superiority of these dual-task training interventions.

Study Objectives:

• To test the feasibility and acceptability of home-based C-DTT and M-DTT interventions.
• To assess the acceptability and utility of the outcome measures, from the participant perspective.
• To assess safety by monitoring for any adverse events or serious adverse events.
• To assess the feasibility and acceptability of the safety monitoring process, from the participant perspective.
• To assess the potential effect of C-DTT and M-DTT on standing and walking balance.

Inclusion Criteria:

• Self-report a diagnosis of PD
• Are categorized as having mild to moderate PD (based on scoring of the modified UPDRS scale, undertaken via an online interview).
• Can understand and follow instructions.
• Can independently, or with help of a supporter, complete self-report outcome measures.
• Can use web-based/online applications independently, or with help of a supporter.
• Have a supporter (carer, spouse, family member aged ≥18) who is willing and able to act as an exercise buddy.
• Have an available safe training area according to the definition: A 2 meter square clear area immediately next to a wall, with no trip hazards and with the potential to place a chair within the space (for seated rests). The wall needs to be free from hanging objects or shelves and not wallpapered or featuring flaking plaster. This is to ensure safety during training and prevent unintended damage to the wall. (Closed doors may be considered as part of the 'wall' only if they can be securely shut, so that should a near-fall occur with participant's falling against the door, they would not open. They should also be guaranteed not to be opened by other household members (including pets) during the training session (which could potentially cause a fall)).

Exclusion Criteria:

• Neurological, orthopaedic or any other current medical problems other than PD which can affect standing balance (such as stroke, cerebellar disorders, a vestibular impairment, a skeletal fracture (occurred within past six months), severe visual impairment) as this could both risk safety within a standardized training protocol and independently affect treatment outcomes.
• Severe deafness without the support of a signing translator, to ensure that participants will be able to effectively receive communication.
• Those unable to communicate in English, as no translation will be available, and communication is essential in ensuring safety.
• Unable to stand independently for more than 1 minute without requiring external postural support, to ensure safety (and prevent falls) during training and outcome measurement.
• Unsuitable training area according to the definition.

The information from participants and all collected and processed data will be used only for the purpose of this study by the research team. University of Plymouth will keep data about participants for 10 years after the study has finished and then will destroy the data permanently.

Participants will know they are allocated to one group randomly but they will not know which group is this.