Effects of Whole-Body High-Intensity Interval Training on Fitness in Overweight Adults (WB-HIIT)

Effects of a Whole-body High-intensity Interval Training on Cardiorespiratory Fitness, Musculoskeletal Fitness, Body Composition and Blood Parameters in Overweight Subjects

This study aims to evaluate the effects of a supervised whole-body high-intensity interval training (WB-HIIT) program on physical fitness and health outcomes in adults with overweight and obesity. WB-HIIT is a practical and time-efficient training modality based on body-weight exercises performed at high intensity with short recovery intervals. It may offer an accessible approach for improving health in individuals with excess body weight.

Participants aged 18 to 55 years with a body mass index (BMI) between 25 and 35 kg/m² will take part in a supervised 10-week WB-HIIT program, performed in small groups and led by trained exercise professionals. Before and after the intervention, participants will undergo assessments including DXA-based body composition analysis, fasting blood sampling, muscular strength testing, a Chester step test, a maximal graded treadmill exercise test with gas-exchange analysis to determine VO₂peak, and functional evaluations (chair-stand, arm-curl, and 6-minute walk test). Physical activity and dietary intake will also be recorded.

The primary objective of the study is to assess whether WB-HIIT improves cardiorespiratory fitness (VO₂peak) in adults with overweight. Secondary objectives include evaluating changes in muscular strength, body composition, metabolic markers, and functional capacity.

The results may help determine whether an equipment-free WB-HIIT program can serve as an effective and accessible training approach for improving health and physical fitness in adults with overweight and obesity.

Study Overview

• Status: Recruiting
• Conditions: Overweight and/or Obesity
• Intervention / Treatment: Behavioral: Whole-Body High-Intensity Interval Training (WB-HIIT)

Detailed Description

This study investigates the physiological, functional, and metabolic effects of a supervised whole-body high-intensity interval training (WB-HIIT) program conducted entirely in person in adults with overweight and obesity.

Overweight and obesity are associated with decreased cardiorespiratory fitness, metabolic impairments, and increased risk of chronic diseases. In contrast, regular physical activity is known to improve cardiorespiratory fitness, metabolic health, body composition, strength, and quality of life. WB-HIIT, which involves body-weight exercises performed at high intensity with controlled recovery intervals, provides a time-efficient, equipment-free training modality that can be adapted for individuals with excess body weight.

A total of 40 adults aged 18 to 55 years with a BMI between 25 and 35 kg/m² will be recruited and allocated to an intervention and control group. In the intervention group, participants will complete a 10-week supervised WB-HIIT program consisting of 2 to 3 sessions per week. Training sessions will include 8 to 12 whole-body exercises targeting major muscle groups, performed in intervals lasting 20 to 60 seconds with recovery periods adjusted according to participant progression. Intensity will be monitored through heart rate and perceived exertion (Borg CR-10 scale), and progression will be achieved by modifying the number of sets, exercise complexity, and work-to-rest ratio.

All participants will undergo comprehensive pre- and post-intervention evaluations. Body composition will be measured using DXA, and anthropometric measurements will include waist circumference and BMI. Cardiometabolic health will be assessed through fasting blood sampling measuring glucose, insulin, HbA1c, lipid profile, hepatic markers, and additional exploratory biomarkers. Cardiorespiratory fitness will be evaluated using a maximal graded treadmill test with gas exchange analysis to determine VO₂peak and the Chester step test. Functional performance will be assessed through the 30-second chair-stand test, arm-curl test, and 6-minute walk test. Muscular strength will be evaluated through 3-repetition maximum (3-RM) testing and fatigue protocols at 60% of 1-RM for the leg-press and bench-press exercises. Physical activity and dietary habits will also be evaluated before and after the intervention.

The primary outcomes of the study are the changes in VO₂peak and muscle strength following the intervention. Secondary outcomes include changes in body composition, metabolic parameters, and functional capacity. Statistical analyses will include repeated-measures ANOVA and between-group comparisons using parametric or non-parametric methods as appropriate.

This study aims to deepen understanding of the effects of supervised WB-HIIT in overweight adults and to identify practical, scalable training methods that can be implemented in community or clinical settings. The findings may guide the development of accessible exercise-based health strategies for improving fitness and metabolic health in this population.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Julie Carpentier, PhD; Phone Number: +3225553859; Email: julie.carpentier@ulb.be
• Study Contact Backup: Name: Malgorzata Klass, PhD; Phone Number: +325553859; Email: malgorzata.klass@ulb.be

Study Locations

• Belgium
  • Brussels, Belgium
    • Recruiting
    • Université libre de Bruxelles (ULB)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults aged 18 to 55 years.
• Body mass index (BMI) between 25 and 35 kg/m².
• Able to provide written informed consent.
• Able to safely participate in high-intensity interval training.
• For participants with BMI > 30 kg/m²: medical clearance from their general practitioner.

Exclusion Criteria:

• BMI < 25 or > 35 kg/m².
• Presence of any chronic medical condition other than overweight/obesity.
• Known cardiovascular, metabolic, respiratory, or musculoskeletal disease that contraindicates high-intensity exercise.
• Pregnancy.
• Inability to perform exercise testing or complete the WB-HIIT program.
• Any condition judged by investigators to interfere with participation or data interpretation.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: WB-HIIT Intervention; A supervised whole-body high-intensity interval training (WB-HIIT) program performed in small groups. Participants complete 2 to 3 sessions per week for 10 weeks. Each session includes a warm-up followed by 8 to 12 whole-body exercises performed at high intensity for 20-60 seconds with recovery periods of 20-60 seconds. Progression is applied by adjusting exercise complexity, number of sets, and work-to-rest ratio. Heart rate and perceived exertion (Borg CR-10 scale) are monitored.	Behavioral: Whole-Body High-Intensity Interval Training (WB-HIIT); A structured WB-HIIT program using body-weight exercises such as squats, lunges, mountain climbers, and similar multi-joint movements. Sessions last 35-50 minutes and include 3 to 4 sets of interval blocks performed at high intensity. The training is supervised by qualified exercise professionals.
No Intervention: Control Group; Participants in the control group do not receive structured exercise training. They maintain their usual lifestyle and complete the same pre- and post-intervention assessments as the intervention group.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak oxygen consumption (VO₂peak)	Peak oxygen consumption (VO₂peak) will be measured during a maximal graded treadmill exercise test with gas analysis to assess changes in cardiorespiratory fitness following the 10-week WB-HIIT program. VO₂peak will be expressed in mL·kg-¹·min-¹.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Muscular strength	Maximal dynamic strength will be assessed using 3-repetition maximum (3-RM) tests on the leg press and bench press.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Estimated VO₂max from the Chester Step Test	Cardiorespiratory fitness will also be estimated using the Chester Step Test to evaluate submaximal aerobic capacity.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Body composition	Total and segmental (i.e., arms, legs and trunk) body fat mass, lean mass, and visceral fat will be assessed using dual-energy X-ray absorptiometry (DXA). They will all be expressed in kg.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Muscular endurance (fatigue tests at 60% 1-RM)	Muscular endurance will be evaluated by recording the number of repetitions performed at 60% of the estimated 1-RM for leg press and bench press.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Functional performance (chair-stand test)	Lower-body function will be assessed using the 30-second chair-stand test.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Upper-body functional performance (arm-curl test)	Upper-body functional performance will be measured using the 30-second arm-curl test with standardized weights (2 kg for women, 4 kg for men).	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Functional capacity (6-minute walk test)	Functional aerobic capacity will be assessed during a standardized 6-minute walk test, recording distance walked and recovery heart rate.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Blood biomarkers	Fasting blood markers will include glucose, insulin, HbA1c, lipid profile (total cholesterol, HDL, triglycerides), liver enzymes, and exploratory metabolic biomarkers.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Waist circumference	Waist circumference will be measured at the midpoint between the lower rib and iliac crest to assess changes in abdominal adiposity.	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Physical activity level using the International Physical Activity Questionnaire	Self-reported physical activity will be assessed using the short format of the International Physical Activity Questionnaire (IPAQ-short form). The IPAQ-short form assesses physical activity over the past seven days by recording time spent in vigorous activity, moderate activity, walking, and sitting. It converts the time spent in different physical activity intensities into total energy expenditure, expressed in MET-minutes per week. Walking, moderate activity, and vigorous activity are assigned MET values of 3.3, 4.0, and 8.0 respectively. Based on an individual's responses, the physical activity level can be expressed continuously (MET-min per week), or categorised has low, moderate and high (please refer to: https://sites.google.com/view/ipaq/score). Higher values/scores mean a higher level of physical activity.	At Baseline
Dietary intake (3-day food record)	Dietary intake will be evaluated using a 3-day food record analyzed with standardized nutrition software.	The outcome will be assessed once at baseline and once during the week following completion of the whole-body high-intensity interval training intervention.
Weight	Weight will be measured using a scale (in kilograms).	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Height	Height will be measured using stadiometer (in meters).	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.
Body mass index	Weight and height will be combined to report body mass index, expressed in kg/m²	The outcome will be assessed once at baseline and within 72 hours after the last session of the whole-body high-intensity interval training intervention.

Collaborators and Investigators

• Sponsor: Université Libre de Bruxelles
• Investigators: Study Director: Malgorzata Klass, PhD; Prof., Université libre de Bruxelles (ULB), Research Unit in Cardio-respiratory Physiology, Exercise & Nutrition

Publications and helpful links

General Publications

• Scoubeau C, Bonnechere B, Cnop M, Faoro V, Klass M. Effectiveness of Whole-Body High-Intensity Interval Training on Health-Related Fitness: A Systematic Review and Meta-Analysis. Int J Environ Res Public Health. 2022 Aug 3;19(15):9559. doi: 10.3390/ijerph19159559.
• Scoubeau C, Carpentier J, Baudry S, Faoro V, Klass M. Body composition, cardiorespiratory fitness, and neuromuscular adaptations induced by a home-based whole-body high intensity interval training. J Exerc Sci Fit. 2023 Apr;21(2):226-236. doi: 10.1016/j.jesf.2023.02.004. Epub 2023 Mar 10.

Study record dates

Study Major Dates

• Study Start (Actual): November 9, 2022
• Primary Completion (Estimated): June 1, 2026
• Study Completion (Estimated): June 1, 2026

Study Registration Dates

• First Submitted: February 19, 2026
• First Submitted That Met QC Criteria: May 11, 2026
• First Posted (Actual): May 13, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 11, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Overweight; Body Composition; Metabolic health; Cardiorespiratory Fitness; Muscular Strength; Whole-Body HIIT; Body-Weight Exercise
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Overweight
• Other Study ID Numbers: ULB-WBHIIT-OVERWEIGHT-2026-01; P2022-344 (Other Identifier: Comité d'Ethique de l'Hôpital Erasme)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared due to confidentiality requirements and restrictions imposed by the ethics committee.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No