Effectiveness of High-intensity Interval Training (HIIT) Versus Moderate-intensity Continuous Training (MICT) in Reducing Visceral Fat in Adults With Central Obesity

The University of Hong Kong (HKU)

Status: Withdrawn

Conditions: Central Obesity

Treatments: Behavioral: HIIT group; Behavioral: MICT group; Behavioral: Usual care control group

Study type: Interventional

Funder types: Other

Identifiers

NCT04545320

303005-RF008-CB

Details and patient eligibility

About

Obesity is a major risk factor for cardiovascular disease and diabetes as well as all-cause mortality. The prevalence of obesity has continuously increased in most countries and has doubled in over 70 countries since 1980. The World Health Organization (WHO) estimated in 2014 that ~600 million (13%) adults were obese and ~1.9 billion (39%) were overweight worldwide. Notably, United States and China have the highest numbers of obese adults. According to a national survey in China in 2014 conducted among 146,703 Chinese adults aged 20-59, the prevalence of obesity was 13%, central obesity was 25% and overweight was 41%. In Hong Kong, the Behavioural Risk Factor Survey conducted by the Government in 2016 found 39% of adults were classified as overweight or obese, of which 21% were obese. The prevalence of central obesity has also risen steadily since 1999 in America. By 2030 is projected to reach 55.6% in men, 80.0% in women, 47.6% among girls and 38.9% among boys in the United States. Overweight, obesity and central obesity are now already pandemic public health issues causing heavy burden on healthcare system. Nowadays, lifestyle modification interventions still remain as the primary strategy to manage obesity and obesity-related complications, among which exercise is low-cost and effective. Substantial evidences have demonstrated effectiveness of HIIT and MICT in reducing body adiposity and improving body Anthropometry. However, studies have also pointed out "lack of time" is one of the major barriers preventing patients from exercise participation. Therefore, studies have put focus on low-frequency or low-volume exercise in improving health to reduce time commitment and increase exercise adherence. Among substantial evidence, our recent study demonstrated once-a-week HIIT is effectively in improving body composition. The effectiveness of low-frequency exercise in reducing visceral fat has also been explored. However, a recent meta-analysis showed low-frequency exercise is not effective in reducing visceral fat. Notably, the authors pointed out most of studies included in the meta-analysis adopted cycling exercise modality and they suggested walking or running exercise which recruits more body muscles may exert better results. In this study, we propose to adopt walking exercise modality to fill the research gap identified by the meta-analysis. Also, no study has compared the effectiveness of low-frequency HIIT and MICT in reducing visceral fat determined by magnetic resonance imaging (MRI) previously.

Study aim: to examine the effectiveness of once-a-week high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) in reducing visceral fat in adults with central obesity

Sex: All

Ages: 18 to 60 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. Adults aged 18 - 60,
2. Central obesity, defined as BMI ≥25 (obesity classification adopted by the Hong Kong Government) with waist circumference of ≥90 cm for men and ≥80 cm for women (abdominal obesity according to the International Diabetes Federation's Chinese ethnic-specific criterion),
3. Males and females will be included to enhance generalizability.

Exclusion criteria

1. ≥150 minutes moderate-intensity or ≥75 minutes vigorous-intensity exercise weekly,
2. Regular HIIT or MICT (≥1 weekly) in the past 6 months,
3. Medical history of cardiovascular disease, chronic pulmonary or kidney disease, heart failure, cancer, etc.,
4. Somatic conditions that limit exercise participation (e.g., limb loss),
5. Impaired mobility due to chronic diseases (e.g., chronic arthritis/osteoarthritis, neurological, musculoskeletal and autoimmune diseases),
6. Daily smoking and drinking habit,
7. Surgery, therapy or medication for obesity or weight loss in the past 6 months (e.g., gastric bypass, gastric band, sleeve gastrectomy, gastric reduction duodenal switch, and dietitian-prescribed dietary program).

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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0 participants in 3 patient groups, including a placebo group

Usual care control group

Placebo Comparator group

Description:

Subjects in the usual care control group will receive a health education program to provide the usual care information. This program will include 3-month biweekly sessions (70 minutes each session, total 6 sessions) for obesity-related health briefing, dietary caloric restriction advice, lifestyle counselling/consultation and stretching exercise.

Treatment:

Behavioral: Usual care control group

HIIT group

Experimental group

Description:

A 3-month intervention of HIIT will be given to participants allocated to this group. The once-a-week HIIT will be performed in small groups on treadmills supervised by certified athletic coaches. Subjects will perform brisk walking for four 4-min bouts at 85%-95% maximal heart rate (HRmax) with a 3-min active recovery walk at 50%-70% HRmax between each session. There will be a 5-min warm-up and cool-down in each exercise session. The duration of each exercise session will be 35 minutes. Heart rate will be continuously monitored during training using Polar M300 with OH1 optical heart rate sensor.

Treatment:

Behavioral: HIIT group

MICT group

Experimental group

Description:

A 3-month intervention of MICT will be given to participants allocated to this group. The once-a-week MICT will be performed in small groups on treadmills supervised by certified athletic coaches. Subjects will perform mild walking exercise for \~47 minutes at an intensity of 65-75% HRmax. This exercise volume matches the HIIT volume. Heart rate will be continuously monitored during training using Polar M300 with OH1 optical heart rate sensor.

Treatment:

Behavioral: MICT group