The Acute and Chronic Effects of Heel Raises on Central Blood Pressures, Arterial Compliance and Cerebral and Peripheral Oxygen Perfusion After Stroke

After stroke, individuals are more sedentary than their healthy counterparts, with significantly more daily seated time and significantly fewer daily steps with activity levels impaired both immediately post- event and 6 months into recovery. Physical inactivity and increased sedentary time are linked to increased blood pressure; a cause of both incident and recurrent stroke. After stroke, victims suffer from a wide range of complications in terms of physical and cognitive abilities. Hypertension reduces cognitive performance in healthy and clinical populations, and stroke patients are frequently unable (for either physical or psychological reasons) to be physically active enough to reduce blood pressure and maximise cognitive improvements.

Prolonged seated time may also lead to reduced cerebral and peripheral oxygen perfusion. Heel raises may have the potential to improve these parameters without being too physically demanding on a clinical population. This study will investigate whether prescribed heel raises can have an acute and/or chronic effect on peripheral and central blood pressures, measures of central systolic loading, peripheral and cerebral oxygen perfusion and cognitive performance.

This study will recruit thirty chronic stroke sufferers from a local stroke groups. Visit will take place in the morning in a fasted state.

In the first visit, participants will undertake five stroop familiarisation tests. Stroop tests allow assessment of cognitive function. Demographic measures will be taken and baseline pulse wave analysis (PWA [SphygmoCor XCEL]) and pulse wave velocity (PWV) measures will be recorded. Heel raises will be demonstrated to the participants and displayed in a diagram. Participants will practice this movement before maximum voluntary contractions (MVC) will be measured using electromyography.

On each of the second two visits, participants will rest in a seated position for 20 minutes before having PWA, PWV and near infra-red spectroscopy (NIRS) measured at baseline to provide both peripheral and central blood pressures, arterial stiffness, cerebral and peripheral oxygen perfusion. Participants will then either undergo a 180 minute seated protocol or a 180 minute calf raising protocol (10 calf raises per 10 minutes) After 10, 30, 60, 90, 120, 150 and 170 minutes in both protocols, PWA, PWV and Stroop test results will be recorded. EMG will record muscle activation of the affected medial gastrocnemius during heel raises after each 30 minutes. NIRS will continuously record throughout the data collection process. Participants will watch a calming TV show (e.g. a David Attenborough documentary) to pass time without raising blood pressure. Statistical analysis will determine whether the heel raises caused acute alterations in peripheral and central blood pressures, pulse wave velocity, cerebral and peripheral blood flow, muscle activation and cognitive performance.