# Body composition, cardiorespiratory fitness, and neuromuscular adaptations induced by a home-based whole-body high intensity interval training PMID: 36970125 Journal: Journal of exercise science and fitness Published: 2023-04-01 Authors: Scoubeau C, Carpentier J, Baudry S, Faoro V, Klass M ## Question Does 8 weeks of home-based, video-directed whole-body HIIT improve body composition, cardiorespiratory fitness, and neuromuscular function in healthy adults who are below physical activity recommendations? ## Summary This randomized controlled study tested an 8-week video-directed, home-based whole-body HIIT program in insufficiently active healthy young adults. Compared with a non-exercise control group, the HIIT group improved VO2peak, ventilatory threshold, leg lean mass, dynamic and isometric leg strength, and isometric endurance, while total fat mass and most fat measures did not change. ## Population - Twenty-eight healthy insufficiently active adults completed the study, with 14 in WB-HIIT and 14 in control. - Sample size: 28 - Age: WB-HIIT 23.1 +/- 1.3 years; control 24.0 +/- 3.9 years. - Sex: 12 females and 16 males total; each group 6 females and 8 males. - Fitness level: Below WHO physical activity recommendations and no structured endurance or strength training in prior 6 months. - Health status: Healthy adults without medical conditions limiting maximal tests or training. ## Methodology - Randomized controlled trial with two groups and pre-post repeated measures. - 8 weeks - Training was home-based during the COVID-19 pandemic; outcome testing was conducted in a laboratory. - Randomized and controlled study design. ## Protocol - Home-based whole-body HIIT. - Modality: Bodyweight whole-body exercises delivered by video. - Work intervals: 30 seconds all-out. - Recovery: 30 seconds active recovery jogging on the spot. - Sets or repetitions: 3 sets of 4 exercises in weeks 1-2; 4 sets of 4 exercises in weeks 3-8. - Intensity: All-out; achieved mean HR 74 +/- 5% HRmax and maximal HR 88 +/- 5% HRmax. - Session duration: 3-minute warm-up plus 12-16 minutes conditioning plus a few minutes stretching. - Frequency: 3 sessions/week. - Program length: 8 weeks. - Progression: Set count increased and exercise variants/difficulty progressed across four 2-week videos. - Non-exercise control. - Modality: Usual physical and dietary habits. - Program length: 8 weeks. ## Outcomes ### VO2peak Status: improved WB-HIIT increased VO2peak by about 5%; absolute VO2peak rose from 2.35 +/- 0.51 to 2.46 +/- 0.50 L/min, while control changed from 2.25 +/- 0.69 to 2.20 +/- 0.71 L/min. Within WB-HIIT p=0.031; time x group p=0.012. ### First ventilatory threshold Status: improved VO2 at VT1 rose in WB-HIIT from 1.31 +/- 0.33 to 1.56 +/- 0.36 L/min and did not change in control. Within WB-HIIT p=0.002; time x group p=0.012 for absolute VT1 and p=0.006 for relative VT1. ### Body composition Status: mixed Leg lean mass increased from 16.6 +/- 2.7 to 17.1 +/- 2.6 kg in WB-HIIT, but fat mass and most other lean mass measures did not change. Leg lean mass within WB-HIIT p=0.022; time x group p=0.014. ### Leg strength and muscle endurance Status: improved WB-HIIT improved 3-RM leg press, MVC torque, and isometric endurance time. 3-RM time x group p=0.009; MVC torque time x group p=0.001; endurance time improved within WB-HIIT. ### Training intensity relationship Status: improved More time above 80% HRmax was associated with greater absolute and relative VO2peak change. rs=0.56; p=0.049 for absolute VO2peak and p=0.048 for relative VO2peak. ## Practical Insights - A home bodyweight HIIT protocol can be built around 30-second all-out intervals with equal active recovery and progressive exercise variants. - For healthy insufficiently active young adults, 3 weekly sessions over 8 weeks can improve aerobic fitness and neuromuscular performance. - Do not overstate fat-loss effects from this protocol; DXA fat outcomes were largely unchanged. - Intensity fidelity matters: time above 80% HRmax was associated with VO2peak improvement. ## Limitations - Small sample. - Young healthy insufficiently active adults only. - No blinding of participants or investigators during intervention and assessments. - No long-term follow-up. - Early exercise dropouts were replaced. - Heart-rate zones used age-predicted HRmax. ## Safety And Adherence - Three early WB-HIIT participants discontinued after a few sessions; two due to health problems unrelated to the study and one due to lack of time. - Participants with conditions limiting maximal tests or training were excluded. - Heart rate was monitored during sessions and participants could contact investigators for difficulties. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/36970125/) (pubmed) - [DOI](https://doi.org/10.1016/j.jesf.2023.02.004) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10034507/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.