Exercise Snacks in Adults Living With Obesity: Protocol for a Randomized Feasibility Trial.

Background: Rates of obesity worldwide continue to increase and are associated with myriad health risks and socioeconomic burdens. Exercise is a traditional treatment for adults with obesity to increase physical activity levels, improve cardiorespiratory fitness, and reduce cardiometabolic risk. However, many people living with obesity do not engage in enough physical activity to achieve health benefits and often cite a perceived lack of time, lack of access to equipment, and stigma as barriers. "Exercise snacks" are short (~1 min) isolated bouts of vigorous exercise performed sporadically throughout the day that may be a viable strategy to improve fitness and cardiometabolic health. It is unknown whether exercise snacks are a feasible option in the real world for people living with obesity. Objective: This study aims to conduct a pilot randomized clinical trial (RCT) to determine the feasibility and preliminary efficacy of a 12-week smartphone app-supported exercise snacks intervention with behavior change counseling for improving cardiorespiratory fitness and other indices of cardiometabolic health in previously inactive adults living with obesity. Methods: A 2-site, parallel arm, RCT will be conducted in Kelowna and Hamilton, Canada. Eighty inactive adults living with obesity will be randomized to an exercise snacks or stretching/mobility exercise comparator group for 12 weeks. The former will complete 4 × 1-minute bouts of vigorous exercise at least 5 days per week, and the latter will perform mobility or stretching exercises using the same schedule. Interventions will be delivered through a customized smartphone mobile app and will be tailored to the participants' schedules via onboarding counseling sessions, with ongoing telephone check-in call support at weeks 1, 2, 4, and 8. This pilot RCT will focus on feasibility as reflected by rates of recruitment, adherence, and dropout. We will also assess cardiorespiratory fitness, anthropometric markers, and routine blood health markers (eg, glucose, insulin) at baseline and postintervention. Results: This study is funded through the Heart & Stroke Foundation of Canada Grants-in-Aid program (2024/2025). Recruitment began on July 18, 2025 (Kelowna) and in November 2025 (Hamilton). As of March 31, 2026, we have enrolled 65 participants (University of British Columbia Okanagan, n=51; McMaster University, n=14). Data analysis will begin once all enrolled participants have completed the trial, and we expect to publish the results of the trial in winter 2027. Conclusions: This study will test an RCT protocol, provide evidence on the feasibility of exercise snacks in inactive adults living with obesity, and report preliminary effect size estimates for their ability to improve cardiometabolic health.