High-intensity interval training or continuous training, combined or not with fasting, in obese or overweight women with cardiometabolic risk factors: study protocol for a randomised clinical trial

Introduction

Physical inactivity and increased caloric intake play important roles in the pathophysiology of obesity. Increasing physical activity and modifying eating behaviours are first-line interventions, frequently hampered by lack of time to exercise and difficulties in coping with different diets. High-intensity interval training (HIIT) may be a time-efficient method compared with moderate-intensity continuous training (CT). Conversely, diets with a fasting component may be more effective than other complex and restrictive diets, as it essentially limits caloric intake to a specified period without major diet composition changes. Therefore, the combination of HIIT and fasting may provide incremental benefits in terms of effectiveness and time efficiency in obese and sedentary populations. The aim of this study is to determine the effect of HIIT versus CT, combined or not with fasting, on microcirculatory function, cardiometabolic parameters, anthropometric indices, cardiorespiratory fitness and quality of life in a population of sedentary overweight or obese women with cardiometabolic risk factors.

Methods and analysis

Sedentary women aged 30–50 years, with a body mass index ≥25 kg/m² and cardiometabolic risk factors, will be randomised to HIIT performed in the fasting state, HIIT performed in the fed state, CT in the fasting state or CT in the fed state. Cardiometabolic parameters, anthropometric indices, cardiorespiratory fitness, quality of life and microvascular function (cutaneous capillary density and microvascular reactivity evaluated by laser speckle contrast imaging) will be evaluated before initiation of the interventions and 16 weeks thereafter.

Ethics and dissemination

The trial complies with the Declaration of Helsinki and has been approved by the local ethics committee (Instituto Nacional de Cardiologia, Rio de Janeiro, Brazil). All patients provide written informed consent before enrolment and randomisation. The study's results will be disseminated to the healthcare community by publications and presentations at scientific meetings.

Trial registration number

NCT03236285.

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