Breaking up Sedentary Time in Rheumatoid Arthritis

This study will verify the effects of breaking up sitting time with short bouts of light intensity walking on vascular function in women with rheumatoid arthritis.

Women diagnosed with rheumatoid arthritis will participate in this randomized crossover trial. In one of the experimental sessions, the participants will remain 4-h on uninterrupted sitting, and in another day they will perform 3-min light intensity walk every 30 min to break up the sitting position. Vascular function will be assessed before and after each intervention using the following devices/techniques: a) transcranial Doppler ultrasound to assess the middle cerebral artery blood flow velocity at baseline and in response to CO2 breathing (5% CO2 mixture for 3 min), and to repeated sit-to-stand transitions; b) a multi-frequency linear transducer (7-12 MHz) attached to a high-resolution ultrasound machine to assess femoral artery dilation after reactive hyperemia (i.e., flow-mediated dilation); c) a laser Doppler probe attached to the skin surface of the right shin in order to quantify the Laser Doppler flux at baseline and during reactive hyperemia. Additionally, healthy age- and body mass-matched women will be recruited and will only perform the pre-intervention tests.

Participants with rheumatoid arthritis will attend the laboratory at Liverpool John Moores University on 2 occasions. During these visits, they will be submitted to the intervention or the control and will also undertake a series vascular tests prior- and post-intervention/control.

During this session, participants will be requested to remain seated during 4 hours, but the sitting will be interrupted every 30 min with a 3-min light-intensity walking.

During this session, participants be requested to remain seated during 4 uninterrupted hours (excepted for visiting the toilet) in a comfortable chair

Participants will breathe a 5% carbon dioxide mixture for 3 min during which time MCAV reactivity to CO2 will be assessed using continuous bilateral transcranial Doppler ultrasound.

Participants will be asked to complete a series of repeated sit to stand moves (coached by a member of the research team) for a 5-minute period, during which time MCAV will be assessed using continuous bilateral transcranial Doppler ultrasound. Beat by beat blood pressure will also be assessed using finger photoplethysmography.

Brachial artery endothelial function will be assessed through flow-mediated dilation using vascular ultrasound.

During all procedures, beat by beat finger blood pressure will be measured on the middle finger of the right hand using photoplethysmography.

Superficial femoral artery endothelial function will be assessed through flow-mediated dilation using vascular ultrasound.

Skin blood flow response to hyperemia will be assessed using a laser doppler probe attached to the shin and forearm.

Immediate recall of the California Verbal Learning Test-2 will be used to assess verbal learning and memory.

Vascular ultrasound will be used to assess brachial artery blood flow every hour during the intervention

Vascular ultrasound will be used to assess femoral artery blood flow every hour during the intervention

Inclusion Criteria: Adult women diagnosed with RA From the Rheumatology Clinic at the Liverpool University Hospitals NHS Foundation Trust Aged 18-60 yr Non-smoker for at least 6months Able to provide written informed consent. Exclusion Criteria: Cannot readily read and understand English. Currently smoking or within last 6 months. Alcohol consumption >14units per week. Symptoms of or established cardiovascular disease (except hypertension) Previous stroke or myocardial infarction. History of diabetes or respiratory disease or chronic kidney disease. Musculoskeletal impairment/disability precluding physical activity Unstable medication (change in medication within the 3 months) Aged <18 or > 60 yr Currently pregnant