Effectiveness of exercise intensity in improving cardiorespiratory fitness and body composition among people living with obesity: a systematic review and meta- analysis

Obesity is a prevalent global health issue, strongly associated with numerous comorbidities, including cardiovascular diseases, diabetes, and hypertension. Among the non-pharmacological interventions for obesity management, aerobic exercise modalities such as High-Intensity Interval Training (HIIT) and Moderate Intensity Continuous Training (MICT) have gained significant attention. However, the efficacy of HIIT and MICT in improving cardiorespiratory fitness (CRF) and body composition in obese individuals has yielded inconsistent findings in the literature. Therefore, this study aimed to evaluate and compare the effects of HIIT and MICT on CRF, body fat percentage, (PBF) waist circumference (WC), and visceral fat (VF) in obese adults. A comprehensive search of PubMed, Web of Science, MEDLINE, and Cochrane databases identified randomized controlled trials (RCTs) published up to October 2022. Eligible studies included individuals aged 18–60 years with a BMI ≥30 kg/m², and compared either HIIT or MICT interventions. A total of 21 studies were included in the analysis, and study quality was assessed using the TESTEX tool. Data were analyzed using RevMan 5 software. Results indicated significant improvements in cardiorespiratory fitness (CRF) with HIIT, with a weighted mean difference (WMD) of 0.64 (95% CI: 0.00 to 1.28; P = 0.05), although no statistically significant differences were found for body fat percentage (WMD = -0.37; 95% CI: -0.77 to 0.04; P = 0.06), waist circumference (WMD = 0.29; 95% CI: -0.55 to 1.13; P = 0.48), or visceral fat (WMD = -0.37; 95% CI: -0.88 to 0.14; P = 0.16).In short, both HIIT and MICT demonstrated comparable efficacy in improving key health parameters associated with obesity. These findings suggest that health professionals should prioritize individual preferences and safety considerations when recommending exercise regimens for obese population.