The increasing prevalence of adolescent obesity has emerged as a critical worldwide health issue. In 2022, more than 390 million individuals aged 5–19 were identified as overweight. The proportion of overweight and obese individuals in this demographic has skyrocketed, jumping from just 8% in 1990 to a staggering 20% in 2022 (Bouamra et al., 2022; WHO, 2025). Adolescence, a pivotal stage characterized by significant physical and psychological development (Thivel et al., 2016), is particularly sensitive to the adverse effects of obesity (de Fátima Aguiar Lopes et al., 2021; Su et al., 2024), including cardiovascular diseases, metabolic disorders, plus psychological issues like depression and low self-esteem (Buchan et al., 2010; Manojlovic et al., 2023; Martin-Smith et al., 2019; Inoue et al., 2020; Li and Chen, 2021; Khalafi et al., 2024).

Multiple studies have evaluated the effectiveness of interventions targeting obese adolescents. A systematic review revealed that dietary, physical activity, and behavioral interventions effectively reduced body mass index (BMI) and body fat percentage (BFP) in obese or overweight adolescents aged 11 to 19 (Al-Khudairy et al., 1996). Moreover, mobile health (mHealth) smartphone-based interventions have demonstrated positive impacts on weight management for both overweight adolescents and adults (Metzendorf et al., 2024). Another study highlighted that motivational interviewing combined with peer involvement yielded significant improvements in adolescent obesity management (Wu et al., 2016).

Based on these findings, high-intensity interval training (HIIT) has emerged as a complementary approach with substantial potential to enhance intervention outcomes. HIIT, which involves brief episodes of vigorous exercise interspersed with lower-intensity recovery phases, has attracted significant interest as an efficient and effective approach to enhancing health outcomes in diverse populations (Herget et al., 2016). In contrast to conventional moderate-intensity continuous training (MICT), HIIT has demonstrated comparable or even greater improvements in cardiorespiratory fitness, body composition, and metabolic health, all while demanding a reduced time commitment (Martin-Smith et al., 2020; Dias et al., 2016). This makes HIIT particularly appealing for adolescents, who may face barriers to prolonged exercise due to school schedules, social commitments, or lack of motivation (Domaradzki et al., 2020; Paulino da Silva Bento et al., 2021).

HIIT has been demonstrated to enhance multiple physiological parameters, such as endurance, cardiorespiratory fitness, and engagement in exercise among healthy adolescents. In addition to its established benefits on body composition and cardiovascular fitness, recent research has begun to explore the molecular and biochemical impacts of high-intensity training interventions. Several studies have demonstrated that HIIT or other high-intensity modalities, particularly when combined with nutritional supplementation, can improve inflammatory and metabolic markers. For example, astaxanthin-supplemented high-intensity training was shown to reduce adipokines and cardiovascular risk factors in men with obesity (Saeidi et al., 2023), while spirulina or Zataria multiflora supplementation alongside HIIT reduced tumor necrosis factor-alpha (TNF-α) and retinol binding protein-4 (RBP4), suggesting a systemic anti-inflammatory effect (Tayebi et al., 2018). Additionally, improvements in novel adipokines such as omentin-1 and lipocalin-2 have been reported following HIIT interventions (Atashak et al., 2022), and exercise training has been linked to the modulation of neuregulin 4, a key factor in obesity-related metabolic regulation (Tayebi et al., 2017). These mechanistic findings further highlight the broader potential of HIIT beyond traditional physiological outcomes, and underscore the need to incorporate such biomarkers in future research involving obese youth. Another comprehensive review has indicated that HIIT interventions lead to notable enhancements in VO₂max, diastolic and systolic blood pressure, as well as maximum heart rate among healthy adolescents and children (Men et al., 2023). While numerous studies have explored the effects of low-to moderate-intensity exercises on BMI, blood pressure, and body fat in obese adolescents, the results regarding the efficacy of HIIT for promoting body composition in this population are mixed. A meta-analysis concluded that HIIT leads to favorable body composition outcomes, including reductions in body fat percentage and fat mass, as well as improvements in fat-free mass (Khodadadi et al., 2023). However, other meta-analyses have indicated that HIIT does not produce significant differences in reducing BFP or promoting overall body composition in overweight adolescents (Poon et al., 2024). The inconsistencies in these findings highlight the need for additional studies to determine HIIT’s precise impact on obese adolescents. Existing studies indicate: 1) mixed findings on HIIT’s impact across diverse physiological measures; 2) a lack of systematic reviews and meta-analyses focused on the Impact of HIIT on obese adolescents; and 3) a lack of comprehensive analyses of how HIIT influences specific physiological parameters in this population.

This study aims to perform a systematic review and meta-analysis evaluating HIIT’s impact on health-related outcomes in obese adolescents. By integrating findings from observational studies and randomized controlled trials (RCTs), it seeks to address a crucial question: To what extent does HIIT enhance physiological parameters. Additionally, the study will shed light on current gaps in the existing body of research and provide actionable insights to inform the creation of specialized interventions for this particular demographic.

This systematic review and meta-analysis examined the effects of HIIT on key health-related outcomes in obese adolescents. A total of 11 RCTs involving 611 participants aged 11–17 years were included. The findings indicate that while HIIT does not significantly impact BMI, it has substantial effects on reducing BFP, improving VO₂peak, enhancing HDL levels, and lowering SBP. These results underscore the potential of HIIT as an effective intervention for improving body composition and cardiovascular health in obese adolescents, despite its limited effect on BMI.

The studies included in our analysis primarily focused on adolescent populations, with sample sizes ranging from small experimental school-based cohorts (e.g., Cao et al., 2022; Meng et al., 2022) to larger obesity clinic populations (e.g., Eggertsen et al., 2025). The target age groups varied across studies, with most participants falling within the range of 11–17 years. For the small sample size, it is the potential concern regarding the impact of HIIT on adolescent development, adolescence is a pivotal growth phase marked by notable physiological and hormonal shifts that can impact the body’s reaction to HIIT (Rogol et al., 2002). Some of included studies showed some concerns of other bias in small sample sizes, which could amplify random errors and limit statistical power. Notably, studies included participants from specialized obesity clinics and schools, respectively, an important consideration is the variability in study settings, this distinction may have influenced the effectiveness and implementation of HIIT interventions.

The intervention environment is one of key factor which may impact on the effectiveness of intervention. Clinical settings typically have trained healthcare professionals, such as exercise physiologists, sports medicine specialists, or physiotherapists, who can tailor HIIT programs to individual needs, closely monitor participants, and provide immediate intervention if adverse effects arise (Song and Lan, 2024). This level of expertise may enhance adherence, safety, and the reliability of intervention outcomes. In contrast, school-based HIIT programs often rely on physical education teachers or general instructors, who may not have specialized training in exercise prescription for obese adolescents. As a result, variations in instruction quality, intensity regulation, and injury prevention strategies could lead to inconsistent outcomes across studies (Martin-Smith et al., 2020).

Additionally, geographic diversity was evident, with studies conducted in China, South Africa, the United States, Spain, Poland, Brazil, and Denmark, reflecting the global interest in HIIT as a potential strategy for addressing obesity-related health concerns in youth. A key observation is that studies from developed countries, particularly in Europe and North America, tended to implement standardized HIIT protocols with controlled intensity, structured progression, and professional supervision. These interventions often adhered to established exercise guidelines and incorporated advanced monitoring techniques, such as heart rate tracking and metabolic assessments, ensuring precise execution and evaluation of HIIT programs (Eddolls et al., 2018). In contrast, studies from developing regions, such as parts of Asia and Africa, demonstrated greater variation in intervention design, with some employing locally adapted HIIT programs that differed in duration, intensity, and supervision quality. These discrepancies may stem from differences in resource availability, access to professional training, and cultural attitudes toward structured exercise programs (Costigan et al., 2021).

Furthermore, socioeconomic factors and healthcare infrastructure may influence the effectiveness and sustainability of HIIT interventions. Adolescents in developed regions may have better access to fitness facilities, trained exercise professionals, and consistent follow-up assessments, enhancing adherence and long-term outcomes. Conversely, in lower-income settings, logistical barriers such as inadequate sports infrastructure, lack of trained personnel, and lower participant retention rates could limit the effectiveness of HIIT programs (Stavrinou et al., 2018).

The reviewed studies implemented various HIIT protocols, differing in training modality, intervention length, session duration, and frequency. The intervention frequency varied between 4 and 24 weeks. Short-term interventions (4–12 weeks) demonstrated rapid physiological improvements, including enhanced cardiorespiratory fitness, reduced adiposity, and improved metabolic markers (Eddolls et al., 2018). These benefits may be attributed to the immediate physiological responses to high-intensity exercise, such as increased mitochondrial biogenesis, improved insulin sensitivity, and enhanced fat oxidation (Weston et al., 2014). However, while short-term HIIT has been shown to elicit significant improvements, there are concerns regarding its long-term sustainability. Studies indicate that shorter training durations may not provide sufficient time for adolescents to establish habitual physical activity behaviors, potentially limiting the maintenance of these benefits post-intervention (Bond et al., 2017).

Conversely, longer intervention duration offer the advantage of progressive physiological adaptations and sustained behavioral changes. Prolonged HIIT programs allow for more substantial improvements in body composition, cardiovascular function, and metabolic health. Studies have shown that extended HIIT interventions contribute to greater reductions in visceral fat, improved lipid profiles, and enhanced muscular endurance (Gillen and Gibala, 2018). Furthermore, longer training periods may facilitate better adherence to exercise routines, fostering long-term engagement in physical activity (Stavrinou et al., 2018). However, the challenge with extended interventions lies in participant retention, as motivation may decline over time due to increased physical and psychological demands (Lubans et al., 2022).

Most of included studies utilized short term sessions. Shorter sessions were characteristic of sprint-based HIIT interventions (e.g., Cao et al., 2022; Boer et al., 2014; Meng et al., 2022), whereas moderate to longer sessions were employed in more traditional HIIT studies (e.g., Su et al., 2024; Tas et al., 2023). Short-duration HIIT sessions have gained popularity due to their efficiency and feasibility, particularly for adolescents with low exercise tolerance or limited time availability. Research indicates that short HIIT sessions can enhance cardiovascular health, insulin sensitivity, and fat metabolism (Sandbakk et al., 2013; Tjønna et al., 2009). The physiological benefits are primarily attributed to the high-intensity nature of the training, which induces rapid mitochondrial adaptations and enhances glucose uptake (MacInnis and Gibala, 2017). However, shorter sessions may limit total energy expenditure, which could reduce their effectiveness in promoting significant fat loss and long-term metabolic improvements (Buchan et al., 2013). Additionally, shorter training durations may not provide sufficient stimulus for substantial muscular adaptations compared to longer sessions.

Long term session durations may offer additional benefits by increasing total energy expenditure and promoting greater improvements in body composition and cardiovascular health. Studies indicate that longer training duration enhance fat oxidation, improve lipid profiles, and lead to greater reductions in body fat percentage (Weston et al., 2014; Viana et al., 2019). Furthermore, prolonged exercise sessions provide more opportunities for skill development, aerobic conditioning, and muscular endurance improvements. However, the increased physical demand of longer HIIT sessions may lead to higher dropout rates, particularly among obese adolescents who may experience greater fatigue and discomfort (Dias et al., 2018). Moreover, excessive session duration without proper recovery could increase the risk of over training and injury, potentially discouraging long-term participation in physical activity (Lubans et al., 2022).

Notably, a research studied by Tian et al. (2021) revealed that a 24-week, 3-sessions-per-week protocol resulted in notable enhancements in BMI and BFP, emphasizing the potential of long-term HIIT interventions in managing adolescent obesity. A minimal training frequency of once per week provides limited benefits, as high-intensity exercise is needed for long-term adaptations. A single HIIT session can improve insulin sensitivity and mitochondrial function (Little et al., 2010), but sustained benefits like fat reduction and aerobic capacity require more frequent training (Weston et al., 2014). Lower frequency hinders neuromuscular and cardiovascular adaptations, reducing fitness improvements in obese adolescents (Eddolls et al., 2017). Training twice weekly balances effectiveness and adherence, enhancing VO₂ max, fat loss, and lipid profiles while minimizing overtraining risk (Logan et al., 2014). Increasing frequency to three times per week amplifies metabolic and cardiovascular benefits but raises fatigue and dropout risks (Ouerghi et al., 2017). Monitoring training load and ensuring recovery are crucial for effective HIIT implementation.

The most commonly assessed outcomes included BMI, BFP, VO₂peak, SBP, and HDL levels in this study. The observed improvements in BMI and BFP across multiple studies highlight HIIT’s effectiveness in reducing adiposity among adolescents (e.g., Eggertsen et al., 2024; González-Gálvez et al., 2024b; Su et al., 2024). Previous studies have reported reductions in pro-inflammatory markers (e.g., TNF-α, RBP4), improvements in adipokines (e.g., lipocalin-2, omentin-1), and cardioprotective mechanisms involving neuregulin 4 and miR-206-mediated HSP60 expression following high-intensity training (Delfan et al., 2022; Supriya et al., 2023). Moreover, researches such as those by Meng et al. (2022) and Cao et al. (2022) demonstrated notable enhancements in VO₂peak, indicating improvements in aerobic fitness. A notable reason in the included studies is the restricted number of physiological parameters assessed, with most studies reporting only two to three indicators. This reason may stem from the need to expand databases and the increased workload associated with incorporating a broader range of physiological measures. Comprehensive assessments, including metabolic markers, muscle composition, and cardiovascular parameters, would offer a fuller insight into the impacts of HIIT on obese adolescents (Song and Lan, 2024). Future studies should aim to incorporate a broader range of physiological indicators to enhance the robustness of findings.

The ROB evaluation showed that the majority of studies had minimal or intermediate bias risks. Few studies caused highest risks due to methodological limitations such as inadequate blinding, incomplete outcome data, and selective reporting, introduce biases that affect the reliability of conclusions. Additionally, inconsistencies in reporting all predefined primary outcomes reduce the clarity of HIIT’s impact. Future research should aim for standardized reporting, balanced sample sizes, and improved methodological rigor to better understand the optimal weekly frequency of HIIT for obese adolescents.

The findings from this meta-analysis indicate that HIIT alone has a limited impact on BMI of obese adolescents, despite conducting a subgroup meta-analysis, the high heterogeneity was associated with the frequency of exercise across different regions, a result consistent with previous studies. BMI may not be an ideal indicator for assessing the effectiveness of exercise interventions, as it fails to differentiate between adipose tissue and muscle mass (Tolfrey et al., 2014; García-Hermoso et al., 2018). However, our analysis shows that HIIT significantly improves BFP and VO₂peak, making these parameters more reliable indicators of intervention effectiveness. Moreover, both of the subgroup meta-analysis indicated that the high heterogeneity was also related to the duration of each exercise session, both of which had significant effects. In addition to subgroup analyses, sensitivity tests were performed to evaluate the influence of individual studies on the pooled estimates. The leave-one-out approach confirmed that no single study disproportionately influenced the results for BMI, VO₂peak, or BFP. This reinforces the robustness of the observed effects and suggests that the high heterogeneity was not primarily driven by outlier studies but may instead reflect broader variation in intervention design, sample characteristics, or delivery settings. Nonetheless, future trials with larger sample sizes and standardized reporting of protocol fidelity and bias risk are warranted to further validate these findings and reduce interpretive uncertainty. HIIT is known to promote fat loss while simultaneously increasing lean muscle mass (Callahan et al., 2021). Since BMI is a crude measure that does not differentiate between these components, reductions in fat mass may be offset by muscle gains, leading to minimal changes in BMI despite meaningful body composition improvements. In contrast, reductions in BFP provide a clearer reflection of the effectiveness of HIIT in reducing excess adiposity.

VO₂peak, a marker of cardiovascular fitness, was also significantly improved following HIIT interventions. This aligns with previous studies demonstrating that HIIT enhances cardiorespiratory fitness through repeated exposure to high-intensity bouts, improving oxygen uptake efficiency (Buchan et al., 2013). Increased VO₂peak is associated with better metabolic health, insulin sensitivity, and overall cardiovascular function, making it a critical outcome in assessing the benefits of HIIT in obese adolescents.

HIIT significantly enhances HDL cholesterol and SBP, demonstrating its vital impact on cardiovascular health in obese adolescents. The interaction between cardiovascular fitness, lipid profile, and blood pressure regulation is well-established, as VO₂peak improvements are often accompanied by favorable changes in lipid metabolism and vascular function (Ramos et al., 2015). Enhanced VO₂peak reflects increased cardiovascular efficiency, which may contribute to reductions in SBP through improved endothelial function and arterial compliance (da Silva et al., 2020).

Elevated HDL cholesterol levels correlate with a lower risk of cardiovascular disease, and HIIT has been shown to promote beneficial changes in lipid metabolism by increasing lipoprotein lipase activity and enhancing lipid transport (Scott et al., 2019). However, the effects of HIIT on LDL cholesterol were not consistently reported across the included studies, limiting our ability to assess its impact on this marker. Future research should aim to clarify HIIT’s role in modulating LDL and other lipid components to provide a more comprehensive understanding of its cardiovascular benefits. Additionally, reductions in SBP following HIIT interventions align with previous findings suggesting that high-intensity exercise improves autonomic regulation and arterial elasticity, contributing to better blood pressure control (Batacan et al., 2017). These results reinforce the potential of HIIT as an effective intervention for minimizing heart disease risks in obese adolescents.

This systematic review and meta-analysis provide evidence that HIIT can positively influence health-related outcomes in obese adolescents. Specifically, HIIT was found to significantly reduce BFP, enhance VO₂peak, increase HDL levels, and lower SBP, although its effect on BMI was negligible. However, notable heterogeneity was observed across studies, particularly in analyses of BMI, VO₂peak, and BFP, which was partly explained through subgroup analyses based on protocol characteristics such as frequency and session duration. These findings highlight the importance of standardizing HIIT protocols in future interventions.

Given the variation in study settings, participant demographics, and geographic contexts, caution should be exercised when generalizing the results to broader adolescent populations. Additionally, important health-related biomarkers such as LDL, insulin sensitivity, and inflammatory markers were either inconsistently reported or absent in the included studies, limiting the scope of conclusions regarding HIIT’s full metabolic impact.

From a practical standpoint, structured HIIT programs that involve moderate session durations (30–60 min) performed at least twice per week appear to yield the most consistent improvements. While HIIT shows promise as a standalone intervention, it may also serve as a complementary approach when combined with traditional physical activity or lifestyle interventions. To support implementation in real-world settings, schools and community health programs could incorporate HIIT into physical education curricula or extracurricular programs using minimal equipment. Clinicians and public health practitioners should consider HIIT as a time-efficient, adaptable strategy when developing exercise prescriptions for obese adolescents. Future research should prioritize protocol standardization and long-term follow-up while also exploring additional physiological and psychosocial outcomes.