Psychiatry · Medical Literature
Effects of High-Intensity Interval Training on Mental Health Outcomes in Adolescents and Young Adults: A Systematic Review and Meta-Analysis.
Abstract
Given rising physical inactivity and mental health challenges, time-efficient interventions like High- Intensity Interval Training (HIIT) require rigorous evaluation. This systematic review and meta-analysis synthesized the evidence for HIIT's effects on mental health in adolescents and young adults. Six electronic databases were systematically searched for Randomized Controlled Trials (RCTs) up to September 2025, comparing HIIT (defined as ≥85% HRmax) against a passive control group in non-clinical populations aged 11-29 years. 11 RCTs comprising 1,401 participants were included. The random-effects meta-analysis showed a modest reduction in perceived stress associated with HIIT (SMD = -0.29, 95% CI -0.59 to 0.004, p = .053), although the effect did not reach conventional statistical significance and substantial uncertainty remained. No statistically significant effects were observed for depressive symptoms, anxiety, or psychological wellbeing. HIIT may be associated with modest reductions in perceived stress; however, the certainty of the evidence was low to very low across all outcomes. These findings should be interpreted with caution, and further high-quality research is needed to clarify the effects of HIIT on mental health outcomes.
Clinical relevance
This systematic review and meta-analysis addresses a clinically important gap regarding the mental health utility of High-Intensity Interval Training (HIIT) in adolescents and young adults (aged 11–29 years), a demographic experiencing escalating rates of psychological distress and physical inactivity. As HIIT is increasingly promoted as a time-efficient adjunct intervention in youth mental health contexts, rigorous synthesis of RCT-level evidence is essential to inform evidence-based recommendations. Clinicians prescribing or endorsing exercise-based mental health interventions need to understand the current limitations of the evidence base before recommending HIIT for psychiatric outcomes.
Key findings
1. Eleven RCTs comprising 1,401 participants in non-clinical populations aged 11–29 years were included, with HIIT defined as exercise at ≥85% HRmax compared against passive control groups. 2. HIIT was associated with a modest, statistically non-significant reduction in perceived stress (SMD = −0.29, 95% CI −0.59 to 0.004, p = .053), with the confidence interval crossing the null and substantial uncertainty remaining. 3. No statistically significant effects of HIIT were observed for depressive symptoms compared to passive control. 4. No statistically significant effects of HIIT were observed for anxiety outcomes compared to passive control. 5. No statistically significant effects of HIIT were observed for psychological wellbeing compared to passive control. 6. The overall certainty of evidence was rated as low to very low across all mental health outcomes, limiting the confidence with which any clinical conclusions can be drawn.
Practice implications
Clinicians should not currently recommend HIIT as a standalone, evidence-based intervention for improving depression, anxiety, or psychological wellbeing in non-clinical adolescents and young adults, given the absence of statistically significant effects and low-to-very-low certainty evidence across all outcomes. The trend toward modest perceived stress reduction (SMD = −0.29) is hypothesis-generating but insufficient to drive practice change without corroboration from larger, higher-quality RCTs with standardized HIIT protocols and validated psychiatric outcome measures. Until further high-quality research clarifies the dose-response relationship and identifies potential responder subgroups, HIIT may be considered as part of a broader lifestyle intervention for general health promotion rather than a targeted psychiatric treatment in this age group.