Exploring the efficacy and acceptability of exercise snacks (ES) and sprint interval training (SIT) could provide time-efficient, low-barrier alternatives for individuals, especially those who, due to 'lack of time, environment, and equipment,' struggle to meet traditional physical activity recommendations. This research aims to investigate the effects of ES and SIT, of equal exercise volume, on overweight adults.

Engaging in regular physical activity has been shown to induce a range of beneficial physiological and psychological adaptations, including improved cardiorespiratory fitness, body composition, cardiovascular function, and reductions in negative emotions. However, global participation rates in physical activity remain suboptimal, with little significant improvement. Interviews and surveys have identified several potential barriers to low physical activity levels, with limitations such as 'lack of time, equipment, and facilities' often cited as the main perceived obstacles. Therefore, exploring the minimum effective dose of exercise in real-world settings is essential.

This study will employ a randomized clinical trial to examine the effectiveness and acceptability of two low-volume, high-intensity stair climbing exercises in overweight adults. It adopts a single-blind, parallel randomized design, with the intervention commencing immediately after the initial evaluation and randomization, following a pre-treatment/post-test framework. Eligible participants were recruited via convenience sampling and randomly assigned to one of three groups (one control group and two experimental groups):

1. A control group that will not receive any treatment.
2. Two experimental groups (ES and SIT), which will undergo a stair climbing-based physical training program following the initial evaluation. The two exercise interventions are designed with equal exercise volume, with the only difference being the rest (recovery) time between stair sprints. All exercise sessions are conducted under the supervision of professionals.

The aim of this study is twofold: First, to explore the impact of ES and SIT on cardiorespiratory fitness, body composition, and cardiovascular function in overweight adults. Second, to examine the acceptability of two low-volume, high-intensity stair climbing exercises by assessing participants' (1) acceptability, (2) reactions during the interventions, (3) enjoyment and affective valence during exercise, and (4) intentions at the end.

Inclusion Criteria:

• Men and women aged between 18 and 35 years;
• Overweight but not obese (BMI ≥24 and ≤ 28 kg/m2);
• Physically inactive (3 or less bouts of purposeful exercise per week);
• Ability to understand the research details and voluntarily sign the informed consent form;
• Non-smoker (for >5 years);
• Body weight has been stable over the past six months, with no recent weight gain or loss behaviors;
• Healthy (see exclusion criteria).

Exclusion Criteria:

• Any chronic illness, cardiac, pulmonary, liver, or kidney abnormalities, uncontrolled hypertension, peripheral arterial disease, insulin- or non-insulin dependent diabetes or other metabolic disorders - all ascertained through preliminary screening;
• Individuals with a history of bone, joint or neuromuscular problems or a current musculoskeletal injury ascertained through preliminary screening;
• Abnormal electrocardiogram (ECG) results;
• Currently taking medication that may affect physiological testing;
• Contraindications to exercise.

Due to the nature of exercise interventions, it is difficult to blind study caregivers and participants.