# Comparison of high-intensity interval training and moderate-intensity continuous training on cardiopulmonary function, cardiac autonomic function and vascular function in adolescent boys with obesity: A randomized controlled trial PMID: 39500636 Journal: European journal of sport science Published: 2024 Dec Authors: Su ZY, Yu WL, Yan ZW, Ding DD, Fang CC, Luo QL, Liu X, Cao LZ ## Question To compare HIIT and MICT effects on cardiopulmonary function, cardiac autonomic function, endothelial function, vascular elasticity, and weight control in adolescent boys with obesity. ## Summary This assessor-blind randomized trial compared 8 weeks of treadmill HIIT with workload-matched moderate continuous treadmill training in adolescent boys with obesity at a weight-loss camp in China. Both groups improved VO2peak, body weight, BMI, and brachial-ankle pulse wave velocity. HIIT was not superior for VO2peak or weight outcomes, but it produced larger improvements in flow-mediated dilation and selected heart-rate variability measures. No adverse events were reported. ## Population - Forty-four adolescent boys with obesity recruited from a weight-loss camp in Shenyang, China. - Sample size: 44 - Age: 14 +/- 1 years overall - Sex: Boys only - Fitness level: No regular exercise for at least 6 months before the program; baseline VO2peak 33.16 +/- 6.09 mL/kg/min overall. - Health status: Obesity based on BMI-for-age at least two standard deviations above the median; excluded self-reported metabolic, endocrine, orthopedic, or cardiovascular disease and prescribed medications. ## Methodology - Assessor-blind, two-arm, parallel randomized controlled trial. - 8 weeks - Weight loss camp in Shenyang, China. - Randomized and controlled study design. ## Protocol - HIIT. - Modality: Treadmill exercise. - Work intervals: 10 x 1 min at 85%-95% HRpeak. - Recovery: 10 x 2 min active recovery at 60%-70% HRpeak. - Sets or repetitions: 10 intervals. - Intensity: 85%-95% HRpeak for hard intervals, Borg RPE target 16-17. - Session duration: 40 min total including 5-min warm-up and 5-min cool-down. - Frequency: 3 sessions/week. - Program length: 8 weeks. - Progression: Treadmill speed and incline adjusted to maintain target HR. - MICT. - Modality: Treadmill exercise. - Work intervals: 35 min continuous exercise. - Sets or repetitions: One continuous bout. - Intensity: 65%-75% HRpeak; warm-up and cool-down at 50%-60% HRpeak. - Session duration: 45 min total including 5-min warm-up and 5-min cool-down. - Frequency: 3 sessions/week. - Program length: 8 weeks. - Progression: Treadmill speed and incline adjusted to maintain target HR. ## Outcomes ### VO2peak Status: improved Both groups improved VO2peak: MICT +3.49 +/- 1.53 mL/kg/min and HIIT +4.43 +/- 3.38 mL/kg/min, with no significant between-group difference. Time p < 0.001; group x time F = 1.404, p = 0.243, partial eta2 = 0.033 ### Weight and BMI Status: improved Both groups reduced weight and BMI, with no significant between-group differences. Weight group x time p = 0.230; BMI group x time p = 0.318 ### baPWV Status: improved Both groups decreased baPWV: MICT -24.59 +/- 25.55 m/s and HIIT -26.90 +/- 30.68 m/s, with no significant between-group difference. Group x time F = 0.073, p = 0.789, partial eta2 = 0.002 ### FMD Status: improved Both groups increased FMD, with greater improvement in HIIT: MICT +0.25 +/- 0.46% vs HIIT +1.14 +/- 0.79%. Group x time F = 20.224, p < 0.001, partial eta2 = 0.330 ### Heart-rate variability Status: mixed HIIT improved HF and LF/HF more than MICT; there were no between-group differences for PNN50, RMSSD, SDNN, TP, or LF. HF: F = 7.527, p = 0.009, partial eta2 = 0.155; LF/HF: F = 4.740, p = 0.035, partial eta2 = 0.104 ### Adverse events Status: no clear change There were no adverse events in either the HIIT or MICT groups. ## Practical Insights - For adolescent boys with obesity, 8 weeks of low-volume, supervised treadmill HIIT can improve VO2peak similarly to longer moderate continuous training. - HIIT may provide added endothelial-function and autonomic-balance benefits compared with workload-matched MICT. - Safety and adherence findings depend on screening, supervision, HR monitoring, and low-volume protocol design. - This study does not support claims that HIIT is superior to MICT for weight loss or VO2peak under these matched-workload conditions. ## Limitations - Male-only sample - Asian ethnicity and weight-loss camp setting - No biomarker analyses for metabolic and cardiovascular mechanisms - Low-volume HIIT selected because high-volume HIIT was difficult for obese adolescents to adhere to - Three sessions per week did not reach the 150 min/week physical activity guideline threshold - Dietary recommendation talks were provided to all participants, making exercise-only interpretation less clean ## Safety And Adherence - No adverse events in either HIIT or MICT groups. - Exercise intensity, duration, heart rate, and adverse events were recorded during exercise. - Low-volume HIIT was selected partly due to exercise risk, physical fitness, and prior adherence difficulty with high-volume HIIT in obese adolescents. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/39500636/) (pubmed) - [DOI](https://doi.org/10.1002/ejsc.12207) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11621380/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.