Background: Isometric resistance exercises (IREs) have great potential to improve blood pressure (BP) control.

Methods: This is a pilot randomized controlled trial that will involve 50 patients with hypertension (HT) who do not meet the current physical activity guidelines defined by the World Health Organization. Participants will be randomly assigned in a 1:1 ratio using stratified and blocked randomization to either the IRE (wall squat) group or stretching exercise (active control) group. A well-structured, widely accepted, and validated 24-week wall squat program (2 minutes per exercise, 2 minutes of rest between sets, and 3 sessions per week) will be implemented, as it has been commonly used in previous research. All patients will be followed up for 24 weeks. Control group will receive exact same treatment except that IRE is replaced by frequency-matched and time-matched stretching exercise. The primary outcome measure will be rate of recruitment. Secondary outcomes will include BP parameters from 24-hour ambulatory BP monitoring

Inclusion Criteria:

• a suboptimal daytime SBP of >135-160 mmHg on a 24-h ABPM
• reported no regular physical activity or less than that recommended for adults by the World Health Organization (e.g. <150 minutes of moderate-intensity aerobic exercise per week);
• on stable doses of anti-HT medication(s) for ≥4 weeks if the patient is receiving drug treatments
• agree for no drug changes during the intervention period (24 weeks);

Exclusion Criteria:

• cannot provide informed consent
• unwillingness to repeat ABPM
• relative contraindications to ABPM (i.e. diagnosed atrial fibrillation, nighttime workers, occupational drivers, or patients with bleeding tendencies)
• severe osteoarthritis pending knee replacement surgery
• known secondary HT
• use of ≥3 anti-HT medications at maximum doses or ≥4 anti-HT medications
• SBP or DBP are >160 mmHg or >100 mmHg, respectively, on ABPM
• pregnancy/breastfeeding
• active malignancy