Parkinson's disease (PD) is a condition that affects movement and gets worse over time. It is more common in older adults. People with PD may have symptoms like shaking, stiff muscles, slow movement, and trouble with balance. They may also experience other issues like pain, depression, anxiety, and memory problems, which can make daily life harder.

Physiological resilience is the body's ability to recover or stay strong despite challenges like aging or illness. People with low resilience may struggle to cope with illness, become less active, and have a higher risk of weakness or hospitalization. Since both PD and low resilience are more common in older adults, understanding how PD affects resilience can help improve care.

This study will look at resilience in people with PD by measuring heart, lung, muscle, coordination, memory, and thinking abilities. It will also compare two types of single-session aerobic exercise-cycling and walking on a treadmill-regarding participants' perspectives. Participants will be randomly chosen to do one of these exercises for 40 minutes at a moderate level. Afterward, they will share their thoughts on how enjoyable and comfortable the exercise was and whether they would continue doing it.

Aerobic exercise is often recommended for people with PD, but it is unclear which type is best for people with PD and which type is mostly preferred by participants with PD. The results of this study will help practitioners make better exercise recommendations for people with PD, leading to better symptom management and a higher quality of life.

Parkinson's is a chronic, progressive, neurodegenerative movement disorder. Both genetic and environmental factors may contribute to the development of Parkinson's in an individual. The onset of PD before the age of 50 is rare but does become more common as people age, affecting ~1% of adults over the age of 60 and 4% of those over 85. The most important motor signs of PD are rest tremor, bradykinesia, rigidity and postural instability. Abnormalities in gait, balance, eye movement, posture, speech, and facial expressions are common. Poor balance, gait disturbance, and impaired mobility are among the most important research priorities identified by people living with PD. Furthermore, people with PD frequently experience non-motor symptoms such as pain, anxiety, depression, dementia, and constipation. Collectively, these symptoms lead to deterioration in quality of life, impaired ability to perform activities of daily living, and reduced functional independence, and motor performance.

Physiological resilience refers to the capacity to retain or regain physical function in the presence of diseases or age-related impairments. Poor resilience may raise the likelihood of being vulnerable to stresses, which could lead to negative functional and clinical consequences like a prolonged course of illness/hospitalization, reduced physical activity, an elevated risk of frailty, and even mortality. It is important to assess older populations' physiological resilience (check their readiness levels for potential future stressors). Since the risk of low resilience and prevalence of PD increase with advanced age, there is a relationship between low physiological resilience and PD due to the fact that it can deteriorate the parameters of resilience. Therefore, it is important to explore the characteristics of physiological resilience in PD populations.

This study will explore the characteristics of physiological resilience in terms of muscle strength, muscle mass, neuromuscular function, functional ability, cardiorespiratory fitness, dexterity, and cognition in people with PD.

Moreover, among the several exercise modalities implemented in the rehabilitation of PD symptoms, aerobic exercise is the most frequently employed and it is also a crucial component of the exercise regimen for people with PD according to European and American guidelines, which has been stated as a beneficial tool to promote physiological resilience at all stages of life. However, there is a lack of information in the literature on which aerobic exercise modality is better for this purpose in people with PD. Beyond the investigation of physiological resilience parameters in individuals with PD, this study will also provide valuable feedback from this population group on two single-bout aerobic exercises (cycling vs treadmill walking). Participants will be randomised to conduct either cycling or treadmill walking. Each of these two aerobic exercise sessions will last for 40 minutes and will be conducted at moderate intensity (estimated according to the heart rate maximum (HRmax)). Having conducted a single-bout aerobic exercise session; participants will be asked to complete scales about 'exercise enjoyment, tolerability, emotional state, and intention to continue exercising' as feedback. This study will inform future guidelines for exercise prescriptions for PD rehabilitation. It will be a cross-sectional study that collects data at a single-time point.

Potential participants identified will be sent the PIS. The study will be explained via email or over the phone by a member of the research team if needed. Participants who are willing to participate in the study will then be invited to attend the Medical school at the Royal Derby Hospital site for a screening session. The study will include two visits: 1) screening day, 2) assessment day. We will have a pre-screening via telephone call or email to check they meet the eligibility criteria: diagnosed with PD, adequately mobile (able to walk 30 meters), and willing to take part. If these initial points are satisfied, then participants will be invited for a screening session.

At the screening session, written informed consent will be received from the participants since it is an essential legal and ethical consideration before conducting tests for exercising in health, fitness, and clinical settings. Following completion of the consent process, heart rate, blood pressure, ECG, and medical history including previous and current medication usage will be collected via a screening sheet. The unified Parkinson's disease rating scale (UPDRS) will be used to evaluate the severity of PD. This scale consists of 42 items divided into four categories: Section I (mentation, behaviour, and mood), Section II (activities of daily living, graded as "on" or "off"), Section III (motor exam), and Section IV (complications). The UPDRS battery also includes the Hoehn and Yahr, and the Schwab and England scales.

Participants will have a chance to ask any questions about the study protocol, screening, and eligibility assessments. Screening results will be discussed with a clinician to decide participants' eligibility. If an abnormal screening result is encountered, this will be discussed with the participant, and their GP will be informed in writing. Only those parts of the assessment visit that participants feel comfortable performing will be required of. Participants will have direct supervision from a member of the research team at all times.

Inclusion Criteria:

• Participants who are willing and able to give informed consent for participation in the study
• Participants who can walk 30 meters with or without walking aids
• Participants who have a confirmed diagnosis of Parkinson's disease by a healthcare professional.

Exclusion Criteria:

• Cardio- and/or pulmonary diseases except for well-controlled hypertension and asthma
• Severe cognitive impairment/dementia
• Joint disorders preventing exercise participation
• Current or recent (<2 years) malignancy (excluding minor cancers such as skin cancer, or not receiving chemotherapy or radiotherapy within the last 3 months)

The population will be selected from the community sample at local groups that cater to older persons in general, through our current PPI-E networks, and through nonprofit organisations and charities that assist Parkinson's sufferers. The planned study's benefits, inherent risks, potential adverse events, and anticipated time commitments would all be thoroughly explained to volunteers, along with the methods and protocols that will be used. Interested participants then will be assessed according to the eligibility criteria.