Randomised controlled effectiveness trial (RCT) of isometric exercise (IE) in adults with stage 1 and 2 hypertension. (ISOFITTER)

Research question To determine whether isometric exercise plus standard care significantly reduces blood pressure in Stage 1 and 2 hypertension alongside contextual implementation factors. Background Hypertension treatment includes lifestyle modification and medication if required. Many people do not adhere to lifestyle recommendations, particularly ≥150-minutes/week of moderate activity.

Eight-minutes of isometric exercise (IE) 3x-weekly (24-minutes/week) has consistently reduced blood pressure (BP) in those with sub-optimal BP under laboratory conditions. Success is probably linked to the short duration and accessibility of IE.

Our feasibility study demonstrated the IE wall-squat is deliverable, fits into everyday life, has low dropout and no adverse effects.

Participants liked the innovative intervention; barriers to implementation were identified and have been overcome by developing patient self-prescribed IE.

Whilst feasibility study results showed a clear trend for a reduction in systolic BP (SBP) in both groups at each time point compared to baseline (greater in the intervention group), it was never powered to detect changes in BP, so effectiveness remains unproven.

As such, to detect a clinically relevant BP difference, using our estimated SD for SBP change from baseline of 14.4mmHg, we require 352 participants to complete a follow-on-study. Based on 35% attrition we need to randomise 542. Aims and Objectives To determine the effectiveness of a personalised IE intervention to lower BP.

To understand key implementation contextual factors, such as routes to long-term adherence and experiences. TO establish cost and cost-utility. Methods Recruitment will be via online media advertising and other inclusive alternatives.

Following an eligibility check and consent, those with stage 1/2 hypertension, taking ≤1 anti-hypertensive drug will be invited to participate. Participants will be sent a validated BP monitor. If average SBP is ≥120 mmHg, they will be randomised to standard care (SC) with IE intervention or SC alone.

All participants will be given SC lifestyle advice for managing BP and the intervention group will complete 6-months (some 1-year) of study. IE training will be self-prescribed using an established protocol. Online instructions / video guidance will be provided to ensure participants perform their IE safely and effectively.

An online training diary will monitor training adherence and progress.

Participants will report their home BP, any changes in medication and complete diet/exercise questionnaires at 4-weeks, 3-months and 6-months. Fifty intervention participants will be invited to continue IE for 1-year. Study primary endpoint is change/difference in SBP at 3-months. Timelines for delivery The project will start 01-October-2024 and be delivered in 30-months.

Ethics approval (funded separately) has already started. Site setup, recruitment and data collection will take 2-years, with data analysis completed in the final 6-months. The dissemination period will run 3-months either side of the end-of-study date.

Anticipated Impact and Dissemination Integrating IE training as part of standard care referral routes; establishing evidence to influence future NICE guidelines; further funding to ensure sustained delivery of IE.

Findings will be reported to the NIHR and published in high impact journals; a public summary being universally available and executive summary for providers and commissioners, national and international conference presentation.