Exercise intervention to normalize blood pressure and nocturnal dipping in hypertensive patients (END-HT): protocol of a randomized controlled trial

BACKGROUND: Lack of decrease (≤10%) in systolic blood pressure (BP) during sleep, referred to as non-dipping (ND), independently predicts cardiovascular events and mortality. There has been no prospective and adequately powered randomized controlled trial (RCT) to determine whether exercise, when compared with standard treatment, can normalize ND in patients with hypertension (HT). Further, most patients do not sustain an exercise program by 12 months. METHODS: A 2-arm, assessor-blinded RCT, involving 198 hypertensive Chinese patients who have ND will be conducted to evaluate the effectiveness of a combined exercise (aerobic exercise and resistance training) program to normalize ND. The combined exercise program, "exercise is medicine"(EIM), was developed to maintain exercise habit using a variety of techniques (e.g. 12-week exercise classes, mobile application, wrist trackers, self-scheduling, monitoring, regular feedback, and motivational interviewing). Eligible patients will be randomized to EIM plus usual care or to usual care in 1:1 ratio by stratified randomization according to age and sex. The randomization sequence is blinded to the investigators and allocation is disclosed only after valid consent. Ambulatory BP measurements will be performed at baseline, 3, and 12 months. The primary outcome is proportion of participants with ND at 3 months; secondary outcomes include proportion of participants with ND at 12 months, absolute BP values at 3 and 12 months. Exercise level will be detected by validated questionnaire and compared between 2 arms at 3 and 12 months. CONCLUSION: The trial will examine the efficacy of treating ND and HT by an exercise program.