The first week after a stroke is a particularly important time, as improving blood flow may limit secondary ischaemic damage to the brain and help reduce the overall burden neurological injury and future disability.

Small studies in patients with stroke have shown that moderate aerobic exercise increases blood flow to the brain, however, no studies have evaluated the safety of aerobic exercise within the first week after stroke, nor whether it results in changes to cerebral blood flow.

Remote ischaemic conditioning (RIC) is when ischaemia is induced to a limb for short periods of time by inflating pressure cuffs around arms or legs to above systolic pressures (mmHg). This procedure is performed for periods that avoid physical injury to the limbs, but induce neurohormonal, systemic or vascular changes in the body. These changes often result in improved blood supply to various areas of the body. The use of RIC in the acute period after stroke is currently being investigated in a number of large randomised controlled trials e.g. RECAST, RESIST, however, our understanding of how RIC actually works is incomplete. Importantly, there is scarce data on the acute effects of RIC on cerebral blood flow (CBF), a potentially pivotal mechanism behind its effects.

We propose an exploratory study to evaluate whether it is feasible, acceptable and safe to undertake low and moderate intensity aerobic exercise or remote ischaemic conditioning (RIC) in patients during the acute period after stroke, and whether either of these interventions result in changes to cerebral blood flow velocity (CBFv) in the major cerebral arteries. We will compare any changes to those in a cohort of healthy volunteers.

Inclusion Criteria:

• Adult (age > 18) patients who have suffered acute ischaemic stroke between 2-7 days previously, or healthy adult (>18 years).
• Ability to provide written informed consent
• Ability to mobilise lower body limbs (at least one leg)
• Ability to comply with study procedures in the opinion of the treating physician.

Exclusion Criteria:

• Haemorrhagic Stroke
• Ischaemic stroke < 2 days or >10 days
• Disability preventing lower extremity cycling
• New York Heart Failure Classification stage III/IV
• History of ischaemic stroke
• Current diagnosis of cancer
• Resting Blood pressure > 180 / 100 mmHg
• Clinically unstable
• History or presence of significant peripheral vascular disease in the upper limbs.
• History or presence of complex neuropathic pains or peripheral neuropathy in the arms.
• Presence of lymphoedema in the arms.
• Presence of skin ulceration to the arms.
• Uncontrolled arrhythmia, hypertension, diabetes or angina.
• Acute deep vein thrombosis, pulmonary embolism or pulmonary infection.